Electrical – Electronic – Control Engineering
|
D |
What
computer network device maintenance procedure is recommended to be
increased in frequency when the equipment is located in areas of high
vibration? |
Periodically
cleaning or replacing equipment enclosure air filters. |
Periodically
testing network connections with network analyzers. |
Periodically
blowing out equipment enclosures with compressed air. |
Periodically
checking the connections between devices and components. |
|
D |
What do the
devices labeled "L" in Panel 2 of the illustrated switchboard
represent? Illustration EL-0003 |
power
available lights indicating that the generator is producing a voltage |
load lights
indicating that the generator breaker is closed and the generator is
supplying power to the main bus |
emergency
lighting for the switchboard to enable the meters to be read in case
of power failure |
synchronizing lights used as a backup to the syncroscope for
paralleling purposes |
|
D |
Concerning
the method for the reversal of rotation of a DC propulsion motor, what
statement is true? |
The only
possible method of reversal of rotation direction is by reversing the
polarity of the armature by reversing the armature current direction.
No other method is possible. |
The only
method of reversal of rotation direction is by reversing the polarity
of the field by reversing the field current direction AND by reversing
the polarity of the armature by reversing the armature current
direction SIMULTANEOUSLY. |
The only
possible method of reversal of rotation direction is by reversing the
polarity of the field by reversing the field current direction. No
other method is possible. |
The methods
of reversal of rotation direction are by EITHER reversing the polarity
of the field by reversing the field current direction OR by reversing
the polarity of the armature by reversing the armature current
direction. |
|
C |
As shown in
figures "A", "B", and "C" of the illustration, what is the purpose of
the regenerating mode when transitioning from ahead to astern
operation with a fixed-pitch propeller as driven by an AC synchronous
propulsion motor? Illustration EL-0162 |
It allows
the shaft to use inertia to very gradually slow down to a stop before
reversing direction. |
It allows
the shaft to instantly reverse directions with virtually no slow down
period. |
It allows
regenerative braking to slow down the shaft to a stop before reversing
direction. |
It allows
regenerative acceleration to accelerate the shaft after the reversal
of direction has taken place. |
|
C |
If a digital
multimeter is setup as shown in figures "A" and "B" of the
illustration, what is the status of the silicon diode if the display
reads 4.7 ohms when configured as in figure "A" and reads 490 ohms
when configured as in figure "B"? Illustration EL-0211 |
the diode is
intermittently open |
the diode is
shorted |
the diode is
functioning properly |
the diode is
open |
|
A |
In a
diesel-electric plant, raising the generator's field excitation
current will have what effect on the DC propulsion motor speed? |
increase in
speed |
effect
generator speed only |
effect main
motor speed if done in conjunction with higher generator engine speeds |
decrease in
speed |
|
D |
If a digital
multimeter is setup as shown in figures "A" and "B" to test a silicon
diode, what is the status of the diode if the screen displays 0.70 V
when configured as in figure "A" and displays OL V when configured as
in figure "B"? Illustration EL-0212 |
diode is
open |
diode is
intermittently open |
diode is
shorted |
diode is
operating properly |
|
D |
What
computer network device maintenance procedure is recommended to be
increased in frequency when the equipment is located in areas of high
vibration? |
Periodically
cleaning or replacing equipment enclosure air filters. |
Periodically
testing network connections with network analyzers. |
Periodically
blowing out equipment enclosures with compressed air. |
Periodically
checking the connections between devices and components. |
|
D |
When
troubleshooting the modems, network interface cards, hubs, switches,
and routers of a network, what technique represents the most logical
first step? |
Replacing
suspected faulty network devices with known good devices. |
Testing the
network cabling with an appropriate network analyzer. |
Running a
network utility diagnostic program and generating a report. |
Observing
the status indicator lights of the suspected faulty network device. |
|
B |
What would
be considered the first line of defense in trying to prevent the
build-up of dust on printed circuit boards associated with computer
network devices? |
Removal of
access panels, followed by vacuuming out the equipment with a vacuum
cleaner. |
Periodically
cleaning or replacing any equipment enclosure air filters. |
Removal of
access panels, followed by blowing out the equipment with compressed
air. |
Periodically
flushing out the equipment enclosure with an approved solvent. |
|
C |
Without the
benefit of a specially designed enclosure window for thermographic
analysis, what must be done to obtain accurate, but safe readings
using infrared thermo graphic techniques? |
The infrared
camera recording is taken after waiting a suitable period of time
after de- energizing and isolating in accordance with safety
procedures. |
The infrared
camera recording is taken before de-energizing and isolating in
accordance with safety procedures. |
The infrared
camera recording is taken immediately after de-energizing and
isolating in accordance with safety procedures. |
The infrared
camera recording is taken while energized with the enclosure door open
in accordance with safety procedures. |
|
B |
For the
purposes of shipboard practice, voltages above what threshold would be
considered high voltage? |
440 VAC |
1000 VAC |
4160 VAC |
6600 VAC |
|
A |
When
troubleshooting a printed circuit board, one technique that can be
used is swapping the suspected damaged board with a new board. When
installing the new board which was stored in a specially manufactured
antistatic bag, how may damage due to electrostatic discharge be
prevented? |
Before
touching the board, you should discharge any static buildup on
yourself by touching a conductive surface or use a grounding wrist
strap, and the board should be handled by its insulated edges only. |
Before
touching the board, you should discharge any static buildup on
yourself by touching a conductive surface or use a grounding wrist
strap, and the board should be handled by grasping trace solder
surfaces. |
Before
touching the board, you should discharge any static buildup on the
board by touching the board to a conductive surface, and the board
should be handled by grasping trace solder surfaces. |
Before
touching the board, you should discharge any static buildup on the
board by touching the board to a conductive surface, and the board
should be handled by its insulated edges only. |
|
D |
When a high
voltage system insulation test value is suspect or recorded during an
annual survey, a polarization index test is performed. What is the
polarization index? |
The
polarization index is the ratio of the insulation resistance taken at
one minute to the insulation resistance taken at ten minutes. |
The
polarization index is the ratio of the insulation resistance taken at
thirty minutes to the insulation resistance taken at one minute. |
The
polarization index is the insulation resistance taken at ten minutes. |
The
polarization index is the ratio of the insulation resistance taken at
ten minutes to the insulation resistance taken at one minute. |
|
D |
What is the
name of a TCP/IP application run from the command prompt that sends
datagrams once every second in the hope of an echo response from
another machine (network device) being addressed to test network
connectivity and to verify that TCP/IP is running? |
TRACERT |
FTP |
IPCONFIG |
PING |
|
C |
How is the
main propeller shaft rotation of a conventional AC turbo-electric
drive normally reversed? (Assume that no converters or inverters are
used.) |
reversing
the field polarity of the AC propulsion motor |
reversing
the field polarity of the AC propulsion generator |
reversing
the phase sequence applied to the AC propulsion motor |
reversing
the steam turbine direction of rotation |
|
D |
When
troubleshooting a printed circuit board, one technique that can be
used is component substitution. Upon what basis would a suspected
defective component be substituted with a known good component? |
Component
substitution is not recommended as a troubleshooting technique. |
Methodical
substitution of components starting at one end of the board and
working towards the opposite end. |
Random
substitution of components in no particular pattern. |
Visual
inspection of components or the use of live signal tracing with test
instruments. |
|
C |
An AC
diesel-electric drive ship with synchronous propulsion motors has the
capability for power factor correction. If the power factor associated
with the main power distribution including all motors is 0.7 leading,
what statement is true? |
The
synchronous propulsion motors are under-excited. |
The
excitation status of the synchronous motor cannot be determined. |
The
synchronous propulsion motors are over-excited. |
The
synchronous propulsion motors are normally excited. |
|
A |
An AC
diesel-electric drive ship with synchronous propulsion motors has the
capability for power factor correction. If the power factor associated
with the main power distribution including all motors is 0.7 lagging,
what statement is true? |
The
synchronous propulsion motors are under-excited. |
The
excitation status of the synchronous motor cannot be determined. |
The
synchronous propulsion motors are over-excited. |
The
synchronous propulsion motors are normally excited. |
|
D |
A very
useful Windows utility for discovering or verifying IP addressing
information of a network is "ipconfig". How is this utility program
launched? |
It is run by
clicking on the TCP/IP shortcut icon on the desktop. |
It is run by
clicking on the "ipconfig" icon in start menu or under programs. |
It is run
from the command prompt screen by default by simply bringing up the
command prompt. |
It is run
from the command prompt screen by typing "ipconfig/all". |
|
D |
If a
mechanical mouse of a computer workstation is operating erratically,
what maintenance should be performed? |
Remove the
plastic surround on the underside of the mouse, and after removing the
ball, mechanically clean the limit switches. |
Solvent
should be sprayed onto the underside of the mouse. |
Compressed
air should be directed onto the underside of the mouse. |
Remove the
plastic surround on the underside of the mouse, and after removing the
ball, mechanically clean the two wheels. |
|
A |
No.1 SSDG
was operating in parallel with No.2 SSDG in supplying the 480 VAC main
bus while sharing the electrical load evenly. As a result of a
problem, if No.1 SSDG begins to motorize, but the generator has not
yet tripped out by the action of the reverse power relay, what would
be the indication of this? |
The kilowatt
meter of No.1 SSDG would indicate a negative wattage (a reversed
reading). |
The ammeter
of No.1 SSDG would indicate a higher amperage than when the load was
equally shared with No.2 SSDG. |
The power
factor meter of No.1 SSDG would indicate unity (1.0). |
The kilowatt
meter of No.1 SSDG would indicate a higher wattage than when the load
was equally shared. |
|
B |
In
accordance with 46 CFR Subchapter J (Electrical Engineering), which of
the following starting aids is the ONLY method allowed to ease the
starting of emergency diesel-generator engines? |
Ether
injection systems |
Thermostatically controlled electric jacket water heaters |
Electric,
steam, or hot water heated lube oil heaters |
Electric air
intake heaters |
|
C |
In what
remote temperature indicating system is a voltage generated by the
magnitude of temperature difference between hot and cold junctions? |
Resistance
temperature detector |
Bimetallic
sensor |
Thermocouple |
Thermistor |
|
A |
Where is the
power necessary to energize the howler "relay" coil at the engine room
station as shown in the illustration? Illustration EL-0093 |
comes from
each station's hand-cranked generator |
is supplied
from a battery or ship's power |
comes from
pushing a button on the handset |
is conducted
through the relay's contacts |
|
A |
What
statement is TRUE concerning podded azimuthing propulsors? |
It is an
electric drive system where the propulsion motor is installed in a
submerged housing capable of swiveling. |
It is an
electric drive system using water jets. |
It is an
electric drive system in which the motor drives a controllable-pitch
propeller (CPP). |
It is an
electric drive system that incorporates a DC motor. |
|
D |
In what
applications are semiconductor diodes commonly used? |
photocells |
potentiometers |
power
sources |
rectifiers |
|
A |
In preparing
a battery-operated digital megohmmeter (resistance tester) for use,
what statement is true? |
The circuit
or circuit component under test must be de-energized, AND the
megohmmeter test voltage must be set to a value equal to or greater
than the equipment exposure voltage. |
The circuit
or circuit component under test must be energized, AND the megohmmeter
test voltage must be set to a value less than the equipment exposure
voltage. |
The circuit
or circuit component under test must be energized, AND the megohmmeter
test voltage must be set to a value equal to or greater than the
equipment exposure voltage. |
The circuit
or circuit component under test must be de-energized, AND the
megohmmeter test voltage must be set to a value less than the
equipment exposure voltage. |
|
A |
What is the
name of the device that works in conjunction with an automatic voltage
regulator and is used as the source of magnetizing direct current
delivered to the rotating field of an AC generator? |
exciter |
magnetizer |
alternator |
governor |
|
D |
What is the
total effective resistance of figure "B" of the illustrated circuit if
the resistance of R1 is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms?
Illustration EL-0020 |
0.5 ohms |
1.28 ohms |
1.5 ohms |
12 ohms |
|
B |
In
accordance with 46 CFR Subchapter J (Electrical Engineering),
emergency diesel engine starting systems are required to have
sufficient capacity to provide power for at least how many consecutive
starts? |
3 |
6 |
9 |
12 |
|
B |
In terms of
the type of load in an alternating circuit, in what type of
alternating current circuit will the voltage always lead the current? |
capacitive
circuit |
inductive
circuit |
resistive-capacitive circuit |
resistive
circuit |
|
B |
In DC motor
construction, where are the commutating windings wound? |
opposite
main poles |
interpoles |
adjacent
main poles |
the rotor
core |
|
A |
Regulations
require that shipboard cabling use stranded copper conductors. Why is
copper a superior conductor compared to aluminum? |
Even though
copper is heavier in weight than aluminum, copper has less resistance
than aluminum. |
Even though
copper has more resistance than aluminum, copper is lighter in weight
than aluminum. |
Even though
copper is lower in conductivity than aluminum, copper has more
resistance than aluminum. |
Even though
copper is more corrosive than aluminum, copper is lighter in weight
than aluminum. |
|
D |
Of the
following, what shipboard system is MOST likely to use the synchronous
transmission system featuring a transmitter and receiver? |
Shaft
revolution indicator system |
Centrifuge
RPM indicator system |
Turbocharger
RPM indicator system |
Rudder angle
indicator system |
|
A |
What is the
measure of the opposition that a magnetic circuit offers to the
magnetic lines of force (flux) called? |
reluctance |
inductance |
resistance |
impedance |
|
D,B,C |
When
configuring a digital multimeter as an ohmmeter, what will MOST likely
be displayed on the screen when the test leads are shorted together? |
A reading of
"OL" ohms will be displayed. |
A reading of
residual test lead and internal resistance will be displayed
(typically .2 to .5 ohms). |
A reading of
0 ohms will be displayed. |
B or C could
be correct depending upon the digital multimeter. |
|
B |
In addition
to insulating the outboard bearing pedestal to prevent shaft currents
in an alternator, what else must be insulated? |
The lube oil
piping connections that make a connection to the alternator outboard
bearing pedestal must also be insulated. No such requirement exists
for exciter bearings. |
BOTH lube
oil piping connections AND exciter bearings that make a connection to
the alternator outboard bearing pedestal must also be insulated. |
Exciter
bearings that make a connection to the alternator outboard bearing
pedestal must also be insulated. No such requirement exists for lube
oil piping connections. |
BOTH lube
oil piping connections AND exciter bearings that make a connection to
the alternator inboard bearing pedestal must also be insulated. |
|
C |
Overheating
is suspected in a high voltage bolted bus-bar joint. If the local
continuity resistance is to be checked off-line after the necessary
safety precautions have been taken, what instrument would be used for
the resistance test? |
A
conventional ohmmeter. |
A special
high resistance tester (megohmmeter). |
A special
low resistance tester (microhmmeter). |
Any of the
above ohmmeters would be suitable. |
|
B |
Why must
caution be exercised during the charging of flooded lead-acid storage
batteries? |
both plates
are changing chemically to lead sulfate |
hydrogen gas
can be liberated during charging |
lead
peroxide in the negative plate is poisonous |
the acid
will become weaker |
|
A |
What is the
most convenient instrument for measuring current, voltage and
resistance? |
Multimeter |
Megger |
Barometer |
Hydrometer |
|
C |
Which of the
conditions listed will indicate the need to clean the insulation on
the stator windings of an alternating current induction motor? |
Higher than
normal insulation resistance readings for the given ambient
temperature. |
Lower than
normal operating temperature for the given load and ambient
temperature. |
Higher than
normal operating temperature for the given load and ambient
temperature. |
Excessive
vibration within normal operating speed range for the given load. |
|
C |
When a
battery-operated megohmmeter (insulation tester) is used to perform a
dielectric absorption test, the resistance is measured and recorded
from each conductor to ground each minute for 10 consecutive minutes.
What condition accounts for a gradual rise in resistance each
successive minute? |
The
insulation is contaminated with moisture. |
The
insulation is cracked and otherwise deteriorated. |
The
insulation is in good condition. |
The
insulation has direct continuity with ground. |
|
C |
How can the
loss of residual magnetism in an alternator with a brushless
excitation system be corrected? |
running the
generator at normal speed with the field rheostat fully
counter-clockwise |
allowing the
generator to run at 10% of normal speed for 5 minutes |
using a
storage battery or battery charger to "flash" the field |
running the
rotor in the opposite direction for 5 minutes |
|
A |
In which of
the following branch circuits types would time lag fuses (or
dual-element fuses) be MOST likely used? |
motor
starting circuits |
emergency
lighting circuits |
general
alarm circuits |
main
lighting circuits |
|
D |
A
thermal-magnetic molded case circuit breaker for a 300 kW alternator
is rated at 500 amperes at full continuous load. Which of the
following conditions will MOST likely trip the breaker? |
Sustained
current draw of 450 amperes indefinitely. |
Sustained
current draw of 500 amperes for 3 hours. |
Momentary
current draw of 1000 amperes for 3 seconds. |
Instantaneous current draw of 10,000 amperes for .03 seconds. |
|
B |
Referring to
the illustration, what is the position of the three circuit breakers
labeled in figure A, B, and C respectively? Illustration EL-0033 |
Circuit
breaker in figure A is in the ON position. Circuit breaker in figure B
is in the OFF position. Circuit breaker in figure C is in the TRIPPED
position. |
Circuit
breaker in figure A is in the OFF position. Circuit breaker in figure
B is in the ON position. Circuit breaker in figure C is in the TRIPPED
position. |
Circuit
breaker in figure A is in the ON position. Circuit breaker in figure B
is in the TRIPPED position. Circuit breaker in figure C is in the OFF
position. |
Circuit
breaker in figure A is in the OFF position. Circuit breaker in figure
B is in the TRIPPED position. Circuit breaker in figure C is in the ON
position. |
|
D |
What is the
purpose of a three-phase lighting power transformer bank of a
shipboard distribution system? |
stabilize
the arc in fluorescent lighting fixtures |
increase
source voltage temporarily for striking an arc in fluorescent lighting
fixtures |
transform
electrical energy directly into light energy |
decrease
generating system voltage to a lower voltage suitable for lighting
fixtures |
|
C |
When placed
in a magnetic field, which of the materials listed has the highest
permeability? |
Bakelite |
Glass |
Iron |
Aluminum |
|
B |
The
component labeled "CR1" in the circuit shown in the illustration
serves what functional purpose? Illustration EL-0085 |
it acts as a
low capacitive reactance to smooth ripple |
it
establishes a constant reference voltage for the base of "Q1" |
it rectifies
the varying voltage from the collector of "Q1" |
it varies
its anode/cathode polarity depending on "RL" current |
|
B |
Ships
requiring extremely rapid maneuvering response using propeller shaft
speed and direction as the sole means of controlling propeller thrust
are most likely to use what type of drive system? |
Steam
turbine geared drive |
Diesel-electric drive |
Direct or
geared diesel drive |
Gas turbine
geared drive |
|
C |
In addition
to SF6 gas circuit breakers, of the types listed below, what type of
circuit breaker is used for high voltage practice aboard ship? |
gas-break |
oil-break |
vacuum-break |
air-break |
|
B |
Contact with
any energized electrical system conductor is potentially hazardous and
precautions should be taken to prevent exposure. With all other
factors considered equal (such as voltage, conducting path through the
body and the duration of contact), contact with an energized
electrical system conductor of which system type would produce the
most damaging effect? |
DC systems |
60 Hz AC
systems |
10 kHz AC
systems |
All the
above systems would be equally as damaging |
|
C |
After prior
isolation and lock-out/tag-out procedures are performed, it is still
possible that stored electrical energy within the circuit can pose an
electrical shock hazard. Which electrical device requires discharging
any stored electrical energy before any work may safely begin? |
resistor
bank |
choke coil |
capacitor |
potential
transformer |
|
A |
A magnet
pickup typically produces what type of signal output? |
voltage
pulse |
pure sine
wave |
steady DC
voltage |
high current |
|
B |
Which of the
following electric propulsion motor types requires no brushes or
electrical connections to the rotor? |
DC shunt
wound motor |
AC squirrel
cage induction motor |
AC
synchronous motor |
AC wound
rotor induction motor |
|
C |
A
turbo-generator has a rated output of 1200 kW at 60 Hertz, with a no
load frequency of 61.5 Hertz. What is its speed droop? |
1.025% |
1.500% |
2.439% |
2.500% |
|
C |
Diesel-generators #1 and #2 are operating in parallel with each
machine operating at half-capacity. Diesel-generator #1 suddenly trips
out mechanically due to low lube oil pressure. The reverse power relay
functions properly and trips generator #1 electrically off the board.
In the absence of an automated power management system, which of the
following actions should you carry out FIRST? |
Secure
alarms, reset reverse power relay, and restart #1 engine. |
Start the
emergency generator. |
Strip the
board of all nonvital circuits. |
Ascertain
cause of the low lube oil pressure. |
|
C |
You are
replacing a three-phase induction motor in an application where
equipment could be damaged if the direction of rotation of the motor
is incorrect when connected. Assuming that even momentarily jogging
the motor could damage equipment and that the feeder phase sequence is
ABC clockwise as tested with a phase sequence indicator, what should
then be done to ensure that the motor rotation will be correct
(clockwise) when connected electrically to the line and mechanically
to the load? Assume that the power is off and that the contact-type
motor rotation indicator leads are connected to the motor terminals. |
Rotate the
shaft by hand in the clockwise direction as viewed from the drive end.
With the push to test pushbutton depressed, if the sequence indicates
ABC, phase sequence and motor rotation are NOT in agreement and any
two leads must be interchanged. |
Rotate the
shaft by hand in the clockwise direction as viewed from the drive end.
With the push to test pushbutton depressed, if the sequence indicates
ACB, phase sequence and motor rotation are in agreement and no
connection changes are necessary. |
Rotate the
shaft by hand in the clockwise direction as viewed from the drive end.
With the push to test pushbutton depressed, if the sequence indicates
ABC, phase sequence and motor rotation are in agreement and no
connection changes are necessary. |
Rotate the
shaft by hand in the clockwise direction as viewed from the drive end.
With the push to test pushbutton depressed, if the sequence indicates
ACB, phase sequence and motor rotation are NOT in agreement and all
three leads must be interchanged. |
|
C |
In
accordance with 46 CFR Subchapter J (Electrical Engineering), on
vessels equipped with both temporary and final emergency power
sources, emergency generators are required to automatically start upon
a loss of normal supply voltage. When the potential of the normal
source is eventually restored, what statement is true? |
The
emergency loads must be manually transferred to the normal source, and
the emergency generator must be manually stopped. |
The
emergency loads must be configured to automatically transfer to the
normal source, and the emergency generator must be configured to
automatically stop. |
The
emergency loads must be either manually or automatically transferred
to the normal source, and the emergency generator must be manually or
automatically stopped. |
The
emergency loads must be configured to automatically transfer to the
normal source, and the emergency generator must be manually stopped. |
|
D |
In a podded
azimuthing propulsion system, how is three-phase, frequency and
voltage controlled power delivered to the synchronous propulsion motor
stator windings? |
By the use
of commutator bars and brushes. |
By rotary
transformer action. |
By direct
connection to the stator windings. |
By the use
of slip rings and brushes. |
|
D |
What is the
correct methodology to prevent shaft currents in an alternator? |
Insulating
BOTH the inboard AND outboard bearing pedestals. |
Insulating
BOTH the inboard AND outboard bearing shells. |
Insulating
EITHER the inboard bearing shell OR the inboard bearing pedestal. |
Insulating
EITHER the outboard bearing shell OR the outboard bearing pedestal. |
|
D |
A resistance
is added in series and internally with the analog meter movement of
which of the following instruments? |
DC ammeter |
AC ammeter |
AC frequency
meter |
DC voltmeter |
|
B |
What is the
most practical method of controlling the RPM of a multi-speed AC motor
operating at a constant frequency? |
change the
input voltage |
change the
number of operating poles |
change the
number of brushes |
change the
power factor |
|
A |
Why should
battery rooms be well ventilated during the charging of lead-acid
storage batteries? |
highly
flammable oxygen and hydrogen gases must not be allowed to accumulate |
highly toxic
sulfuric acid gas must not be allowed to accumulate |
highly toxic
lead gas must not be allowed to accumulate |
highly
poisonous chlorine gas must not be allowed to accumulate |
|
C |
The amount
of voltage induced in the stator windings of a modern AC generator is
primarily dependent upon which of the following? |
the
cross-sectional area of the stator windings |
the number
of brushes associated with the commutator |
the strength
of the rotating magnetic field |
the number
of field poles energized |
|
A |
While
standing an "at sea watch" onboard a ship fitted with electrical
propulsion motors, you notice the propulsion transformer core
temperature slowly rising. What should be your FIRST action? |
check the
transformer ventilation fans for proper operation |
reduce load
by tripping lighting circuits |
send the
oiler to look for fires in the transformer |
notify the
bridge that you need to slow down |
|
B |
When you are
making a high potential test (insulation resistance) on the motor
coils of repaired electrical machinery to ground, what would a low
resistance reading indicate? |
good
insulation |
bad
insulation |
high
insulation power factor |
a high slot
discharge factor |
|
A |
When
paralleling an incoming alternator with the bus manually, the
synchronizing lamps grow dim and become totally darkened as the
synchroscope pointer slowly approaches the 12:00 position while
rotating in the fast direction. What does this indicate? |
the incoming
machine is momentarily nearly in synchronism with the bus and its
circuit breaker may now be closed to facilitate paralleling |
the incoming
machine is momentarily 180o out of synchronism with the bus and its
circuit breaker should NOT be closed at this time |
the incoming
alternator is momentarily nearly in synchronism with the bus and its
circuit breaker should NOT be closed at this time |
the incoming
alternator is momentarily 180o out of synchronism with the bus and its
circuit breaker may now be closed to facilitate paralleling |
|
C |
When an
alternator is to remain idle for even a few days, what should be
ensured or manually accomplished? |
manually
open the equalizing bus disconnect switch as required |
insulate the
collector rings with strips of cardboard if applicable |
ensure
energization the space heater circuit (usually automatic) |
manually
lift the brushes and disconnect the pigtails if applicable |
|
C |
What may
happen if the CAPAC system is not turned on when underway? |
The paint
film may be damaged. |
More fouling
may occur on the ship's hull. |
Hull
corrosion may occur at an accelerated rate. |
All of the
above. |
|
C |
What is the
primary advantage of stranded cable over solid cable which establishes
the basis for the requirement for stranded cable for shipboard
applications? |
limits the
number of supports needed for a horizontal overhead run |
reduces the
overall weight of the cable run |
provides the
flexibility required for easy handling and installation |
reduces the
resistance to current flow for a given wire size |
|
C |
What is the
nominal output voltage of a 6 cell lead-acid battery? |
6 volts |
7.5 volts |
12 volts |
18 volts |
|
D |
The motor of
the illustrated motor controller fails to start on an attempted
startup. You ensure the motor has not tripped out on overload, and you
check the disconnect switch closed. With the start button depressed, a
voltmeter reading between 3 and 4, as in figure "A" shown in the
illustration, indicates line voltage. After re-opening the disconnect
switch and verifying the circuit de-energized, what should be your
next step in the troubleshooting process? Illustration EL-0007 |
after
depressing, check the resistance across the normally open start button
contacts (across 2 and 3) |
without
depressing, check the resistance across the normally closed stop
button contacts (across 1 and 2) |
check the
resistance across the contactor coil "M" (across 3 and 5) |
check the
resistance across the normally closed overload relay contacts (across
4 and 5) |
|
A |
The
lamp-type ground detection circuit on the main electrical switchboard
is indicating a ground. When safe to do so, what is the MOST effective
and practical procedure for locating the distribution system ground? |
one by one,
open the individual branch circuit breakers on the suspected
distribution panel until the ground detection lamps no longer indicate
a ground |
one by one,
check all circuits suspected of grounds for continuity |
one by one,
check circuit resistances with a megohmmeter connected between the
suspected grounded line and the distribution panel framework |
one by one,
physically examine the suspected grounded circuit paths while looking
for burned spots |
|
B |
Suppose an
ungrounded 3-phase distribution system is fitted with a lamp-type
ground detecting circuit with 3 lamps. Assuming that an indication of
an accidental ground is displayed continuously, what is the indication
on the switchboard of a single grounded conductor? |
all three
lamps would be extremely dim or go out |
one lamp
would be extremely dim or go out and the others would be extremely
bright |
one lamp
would be extremely bright and the others would be extremely dim or go
out |
all three
lamps would be extremely bright |
|
C |
Periodic
testing using a special sensing device may be performed to detect
potentially dangerous loose or corroded bus bar and controller
connections. What is the name of this testing technology? |
electric
vibro-analysis |
visual
pyrotronics |
infra-red
thermography |
corrosion
electrolysis |
|
C |
In the
schematic of the electrical circuit shown in figure "A" of the
illustration, assuming that C1 and C2 are equal in capacitance, what
is the value of the total capacitance, when compared to the value of
equal individual capacitors? Illustration EL-0038 |
Half |
Equal |
Double |
Squared |
|
B |
In the
illustration of the one-line distribution system diagram, if at sea
the 450 VAC section of the main switchboard experiences a complete
loss of power, what statement is true concerning the operation of the
emergency diesel-generator? Illustration EL-0014 |
It will
automatically start and automatically supply power to the 450 VAC
section of the main bus through the automatic bus transfer device. |
It will
automatically start and automatically supply power to the 450 VAC
section of the emergency bus through the automatic bus transfer
device. |
It will
automatically start but the automatic bus transfer device must be
manually shifted to "Emergency Power" to supply the 450 VAC section of
the emergency bus. |
It must be
manually started but once running will automatically supply power to
the 450 VAC section of the emergency bus through the automatic bus
transfer device. |
|
D |
In terms of
propulsion generator type, power conditioning schemes, and propulsion
motor type, what combination of equipment is included in modern AC-DC
SCR rectified DC propulsion drive systems? |
propulsion
generators which produce AC power that is directly delivered to the
synchronous AC propulsion motor |
propulsion
generators which produce DC power that is directly delivered to the
shunt-wound DC propulsion motor |
propulsion
generators which produce DC power that is converted to AC power for
the asynchronous (induction) AC propulsion motor |
propulsion
generators which produce AC power that is converted to DC power for
the separately excited DC propulsion motor |
|
A |
In referring
to the frequency response filters shown in the illustration, what
determines the band pass or band stop frequencies as appropriate?
Illustration EL-0078 |
The value of
the resonant frequencies associated with L and C |
The value of
the RC time constant |
The
magnitude of the incoming voltage |
The value of
the total load resistance |
|
C |
In
consideration of what a wattmeter is designed to measure, how would a
wattmeter be electrically connected in a circuit? |
In series |
In parallel |
In
series-parallel |
Inductively |
|
B |
How is the
power dissipated as heat in a simple direct current circuit consisting
of one resistive load calculated? |
P/R |
I2R |
(IR)/T |
E/I |
|
D |
For the
purpose of calculating line current, which of the following procedures
should be used to determine the total line current of a three-phase,
delta wound, AC generator? |
Divide the
total amperage in all phases by three. |
Divide the
total amperage in all phases by the square root of three. |
Multiply the
amperage in one phase by three. |
Multiply the
amperage in one phase by the square root of three. |
|
A |
Assuming a
120 VAC input across TP1 and TP2 and a regulated output of 24 VDC
across TP5 and ground, in which section of the 24 VDC power supply
circuit illustrated does the greatest absolute change in voltage level
take place? Illustration EL-0085 |
A |
B |
C |
D |
|
C |
As shown in
all three diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0231 |
NOR gate |
OR gate |
XOR gate |
NOT gate |
|
B |
An
unintended path of low resistance bypassing the intended path and
allowing passage of an abnormally high amount of current is known as
what? |
ground
reference point |
short
circuit |
polarized
ground |
open circuit |
|
A |
A signal
derived from a device output and returned to the device input is
called what type of signal? |
feedback
signal |
monitoring
signal |
reverse
signal |
inverse
signal |
|
C |
A low
voltage, high current testing unit consisting of an autotransformer,
ammeter, and timer may be used to test the proper tripping function of
a three-pole magnetic circuit breaker. What is the correct procedure
for using this apparatus? |
All poles
are tested simultaneously with the clamp-on ammeter clamped around all
three conductors with the common tripping bar removed. |
All poles
are tested simultaneously with the clamp-on ammeter clamped around all
three conductors with the common tripping bar attached. |
Each pole is
tested individually with the clamp-on ammeter clamped around a single
conductor with the common tripping bar attached throughout the test
procedure. |
Each pole is
tested individually with the clamp-on ammeter clamped around a single
conductor with the common tripping bar removed throughout the
procedure. |
|
A |
Which of the
following procedures represents the best method to prevent the
freezing of lead-acid batteries continuously exposed to low
temperatures? |
The battery
should be kept in a fully charged condition. |
The battery
caps should be removed. |
The battery
cap vents should be sealed. |
The battery
should be disconnected from its charging source. |
|
C |
Which metal
is used to face contacts in electrical equipment? |
tin |
nickel |
silver |
chromium |
|
D |
The torque
load that a synchronous motor can handle is dependent on the hold-in
strength of the poles. Hence, to increase the hold-in torque, it is
necessary to ____________. |
decrease the
resistance of the field rheostat |
increase the
torque angle of the rotor magnets |
increase the
3-phase armature winding current |
increase the
direct current supplied to the rotor magnets |
|
A |
A digital
multimeter is set up as an ohmmeter. What does a display reading of
"OL" ohms as read across the ends of a wire conductor indicate? |
open circuit |
meter is
offline |
a partial
short |
a partial
ground |
|
D |
An AC
generator operating in parallel loses its excitation without tripping
the circuit breaker. What will be the result? |
It will
cause the slip rings to melt. |
It will
increase the output amperage between the armature and the bus. |
It will not
affect the faulty generator due to the compensation of the other
generators. |
It will
cause high currents to be induced in the field and stator windings. |
|
D |
In general,
how are nickel-cadmium storage batteries superior to lead-acid
batteries? |
they put out
higher voltages and require no maintenance |
they need
fewer cells in series and use less mounting space |
they are
less costly to replace |
they can
remain idle and keep a full charge for a long time |
|
A |
In general,
what type of starter would be used to connect a three-phase induction
motor to full line voltage at the instant of start-up? |
across-the-line starters |
VFD starters |
resistor
starters |
autotransformer starters |
|
C |
In terms of
consistency (or "stiffness"), what is the most common grade of grease
for most marine applications as set forth by the National Lubricating
Grease Institute (NLGI)? |
NLGI 000 |
NLGI 0 |
NLGI 2 |
NLGI 6 |
|
B |
The setpoint
current at which a magnetic-type overload relay tends to trip may be
increased by turning the dashpot in the "lower" direction. What effect
will this action have? |
reduces
magnetic force on the plunger and requires less current to trip the
relay |
reduces
magnetic force on the plunger and requires more current to trip the
relay |
increases
magnetic force on the plunger and requires more current to trip the
relay |
increases
magnetic force on the plunger and requires less current to trip the
relay |
|
D |
What is the
alarm signal for manning boat stations or boat drills onboard a
merchant ship? |
Continuous
blast of the whistle for not less than 10 seconds supplemented by the
continuous ringing of the general alarm bells for not less than 10
seconds. |
Continuous
blast of the whistle for not less than 3 seconds supplemented by the
continuous ringing of the general alarm bells for not less than 3
seconds. |
General
alarm sounded 3 times supplemented by 3 short blasts of the whistle. |
A succession
of more than 6 short blasts followed by 1 long blast of the whistle
supplemented by a comparable signal on the general alarm. |
|
A |
An
undervoltage release mechanism (UVR) is fitted to all generator
breakers and some main feeder circuit breakers for what primary
reason? |
trip out the
breaker when a severe voltage dip occurs |
trip out the
breaker if the generator overspeeds by 5%, but continues to run |
trip out
generators when there is reversal of power in the main circuit |
trip out
generators in the event of severe arcing or sparking |
|
B |
In figure
"2" of the diagram shown in the illustration, the three-phase power
transformer has a step- down turns ratio of four to one. If a
three-phase 440 volt supply is connected to terminals "A1-B1- C1",
what voltage should develop across terminals "A2-B2-C2"? Illustration
EL-0084 |
64 volts |
110 volts |
190 volts |
762 volts |
|
A |
What device
is best used to test for a short circuit between windings of a
three-phase motor that is not running? |
ohmmeter |
ammeter |
voltage
tester |
infrared
temperature meter |
|
A |
What is the
purpose of a ship's service generator circuit breaker's reverse power
trip? |
prevent
alternator motorization |
protect the
circuit breaker blowout coil |
prevent low
voltage tripout |
prevent main
circuit overload |
|
C |
What
communications system would be operational despite a loss of ship's
electrical power? |
Call-bell
system |
Emergency
loudspeaker system |
Sound-powered telephone system |
Ship's
service telephone system |
|
A |
What
determines the direction of rotation of an AC induction motor? |
direction of
rotation is the same as the direction of the rotating magnetic field |
the
direction of the staggering of the brushes |
the number
of poles being even or odd |
direction of
rotation is opposite of the direction of the rotating field |
|
B |
How much is
the nominal open-circuit voltage of one cell of a fully charged
lead-acid battery? |
1.5 volts |
2 volts |
6 volts |
12 volts |
|
C |
If a
magnetic controller contact fails to pick up when the operating coil
is energized, what could be one possible cause? |
the residual
magnetism of the contact faces |
low spring
pressure |
low applied
voltage to the coil |
dirty
contact faces |
|
A |
In terms of
units, how is the inductance of a coil measured? |
henrys |
amperes |
volts |
ohms |
|
A |
The leads
from an ohmmeter are attached to the leads of the opposite ends of an
AC motor stator coil. If a reading of infinity is obtained, what does
this indicate? |
open stator
coil |
shunted
stator coil |
shorted
stator coil |
grounded
stator coil |
|
C |
What is the
functional name of an electrical device which prevents performing two
or more actions which will result in a dangerous condition? |
mechanical
limit device |
modulating
device |
electrical
interlock device |
monitoring
device |
|
C |
Which of the
following statements represents the main difference between an
electromagnetic relay and an electromagnetic contactor as used in
motor control and power circuits? |
A relay is
series connected and a contactor is parallel connected. |
Contactors
control current and relays control voltage. |
Contactor
contacts can handle heavier loads than relay contacts. |
Contactor
contacts are made from silver and relay contacts are made from copper. |
|
C |
What
property of a material is rated in voltage per millimeter (V/mm) of
insulation thickness that the insulation can withstand without
breaking down? |
Shear
strength |
Tensile
strength |
Dielectric
strength |
Mechanical
strength |
|
A |
Of the
listed factors that influence the magnitude of the voltage induced in
the stator windings of an AC generator operating at a constant 60 Hz
frequency, some are fixed due to the alternator design and one is
variable due to alternator operating conditions. Which of the
following listed factors is subject to be variable during generator
operation? |
strength of
the rotating magnetic field |
rotational
speed at which the magnetic field passes across the stator winding |
number of
field coil turns in series per winding |
number of
armature coil turns in series per winding |
|
B |
AC circuits
may develop resistance, inductance, and capacitance. What is the unit
of measure used to express inductive reactance? |
mhos |
ohms |
farads |
henrys |
|
C |
AC circuits
can possess characteristics of resistance, inductance, and
capacitance. In terms of units of measure, how is the capacitive
reactance of the circuit expressed? |
farads |
mhos |
ohms |
henrys |
|
D |
In a
three-phase circuit, how far apart are the phase voltages? |
160° apart |
180° apart |
360° apart |
120° apart |
|
A |
How does the
resistance of a conductor vary? |
directly as
its length and inversely as its cross-sectional area |
inversely as
its length and directly as its cross-sectional area |
inversely as
its length and inversely as its cross-sectional area |
directly as
its length and directly as its cross-sectional area |
|
B |
Electric
current is the flow of electrons through a conductor. How is the rate
of this flow measured? |
watts |
amperes |
volts |
ohms |
|
C |
The number
of cycles per second occurring in AC voltage is known as what
characteristic? |
phase angle |
half mode |
frequency |
wave form |
|
B |
The device
that most commonly utilizes the principle of electromagnetic induction
by mutual inductance is what? |
rheostat |
transformer |
diode |
transistor |
|
C |
A direct
current passing through a wire coiled around a soft iron core is known
as what? |
magnetic
shield |
electromagnetic domain |
electromagnet |
piezoelectric device |
|
D |
An
accidental path of low resistance which bypasses the intended
resistance and passes an abnormal amount of current is known as what? |
polarized
ground |
open circuit |
ground
reference point |
short
circuit |
|
B |
An
electrical connection between the wiring of an electric motor and its
metal frame is known as what? |
flux leakage |
ground |
eddy current |
impedance |
|
D |
What
statement is true concerning the total power consumed in a series
circuit? |
Total power
is the sum of the powers consumed by each load (resistor) divided by
the number of loads |
Total power
is never more than the power consumed by the largest load |
Total power
is always less than the power consumed by the smallest load |
Total power
is the sum of the powers consumed by each load |
|
B |
Consider a
series circuit employing two resistors. What is true about the
resistance value of the second resistor compared to the first when the
voltage drop across the first resistor is one half the source voltage? |
the second
resistor has a resistance value that is half of the first |
the second
resistor has a resistance value equal to that of the first |
the second
resistor has a resistance value double that of the first |
the second
resistor has a resistance value relative to that of the first which
cannot be determined |
|
D |
Which of the
following statements is correct for the illustrated circuit in figure
"B"? Illustration EL-0020 |
R1', 'R2',
and 'R3' are connected in parallel. |
The total
resistance equals 1/R1 + 1/R2 + 1/R3. |
The voltages
measured across 'R1', 'R2', and 'R3' are equal. |
R1', 'R2',
and 'R3' are connected in series. |
|
C |
What happens
to the current in a series circuit when the voltage remains constant
and the resistance increases? |
increases |
increases by
the square |
decreases |
remains the
same |
|
D |
What is true
concerning all of the connecting conductors of a DC series circuit? |
they all
have the same power expended in them |
they all
have the same resistance to current flow |
they all
have the same voltage drop across them |
they all
have the same current passing through them |
|
A |
What would
be the total capacitance of the circuit illustrated in figure "A" if
the value of capacitor C1 was 100 microfarads and capacitor C2 was 50
microfarads? Illustration EL-0038 |
150
microfarads |
2500
microfarads |
75
microfarads |
5000
microfarads |
|
D |
Which
statement is true concerning the total power consumed in a parallel
circuit? |
The total
power is never more than the power consumed by the largest load. |
The total
power is the sum of the powers consumed by each load (resistor)
divided by the number of loads. |
The total
power is always less than the power consumed by the smallest load. |
The total
power is equal to the sum of the powers consumed by each individual
load. |
|
C |
As shown in
figure "A" of the illustration, with the switch closed what statement
is true if "R1" and "R2" have unequal resistance values? Illustration
EL-0019 |
The energy
dissipated in 'R1' will be the same as the energy dissipated in 'R2'. |
The voltage
drop across 'R1' will not be equal to the voltage drop across 'R2'. |
The current
flow through 'R1' will differ from the current flow through 'R2'. |
The current
flow through 'R1' will equal the current flow through 'R2'. |
|
B |
What will
happen to the total circuit resistance when additional parallel
circuits are added to a circuit? |
it will
increase, causing a decrease in the line voltage |
it will
decrease, causing an increase in the total load current |
it will
decrease, causing an increase in the line voltage |
it will
increase, causing a drop in the total load current |
|
C |
Four lamps
are connected in parallel in a single circuit. If one of the lamp
burns out, what will happen to the other lamps? |
become
brighter |
all go out |
burn with
their original intensities |
become
dimmer |
|
A |
What
statement is true concerning the electrical diagram shown in figure
"B" of the illustration? Illustration EL-0019 |
R1', 'R2',
and 'R3' are connected in parallel. |
The total
resistance equals R1 + R2 + R3. |
R1', 'R2',
and 'R3' are connected is series. |
The voltages
measured across 'R1', 'R2' and 'R3' will be different if 'R1', 'R2'
and 'R3' have different values. |
|
A |
Which of the
following statements is true concerning circuits with parallel
connected resistances? |
The total
current flow equals the sum of the individual currents. |
The total
resistance equals the sum of the individual resistance. |
The total
current flow equals the reciprocal of the sum of the individual
currents. |
The total
voltage equals the sum of the individual voltages across each
resistance. |
|
B |
What is
statement is true concerning the total resistance of a parallel
circuit? |
The total
resistance is equal to the sum of the individual branch resistances. |
The total
resistance is smaller than the lowest branch resistance. |
The total
resistance is equal to one-half the sum of the individual branch
resistances. |
The total
resistance is larger than the greatest branch resistance. |
|
C |
Which of the
following statements concerning a circuit with parallel connected
resistors is correct? |
The total
resistance equals the sum of the individual resistances. |
The total
current flow equals the reciprocal of the sum of the individual
currents. |
The voltage
drop across each resistor is the same. |
The total
voltage equals the sum of the individual voltages across each
resistance. |
|
A |
Which of the
electrical properties listed will always be the same across each
component in a parallel circuit? |
Voltage |
Resistance |
Impedance |
Current |
|
A |
What should
be the primary consideration when choosing a battery for a particular
application? |
amp-hour
capacity |
stability
under charge |
terminal
polarity |
ambient
temperature rise |
|
D |
The wet-cell
storage batteries shown in the illustration are connected in what
configuration? Illustration EL-0070 |
series |
compound |
tandem |
parallel |
|
B |
The
individual 6 volt lead-acid batteries, when connected as shown in the
illustration, as a battery bank would produce how many volts?
Illustration EL-0070 |
24 |
6 volts |
12 volts |
18 |
|
A |
How many
cells are within in a 24 volt lead-acid battery? |
twelve cells |
three cells |
six cells |
four cells |
|
A |
The nominal
open-circuit voltage of one cell of a fully charged lead-acid battery
is approximately how many volts? |
2 volts |
1.5 volts |
12 volts |
6 volts |
|
A |
In the
illustrated views of a lead acid battery as shown in figures "A" and
"B", what battery component has the sole function of preventing the
individual plates in the negative plate group from coming into direct
contact with the individual plates in the positive plate group?
Illustration EL-0031 |
separators |
cell
dividers |
casing |
series
connecting straps |
|
B |
The
electrolyte used in a nickel-cadmium battery is distilled water and
what other substance? |
lead sulfate |
potassium
hydroxide |
zinc oxide |
diluted
sulfuric acid |
|
A |
In general,
why are nickel-cadmium storage batteries superior to lead-acid
batteries? |
they can
remain idle and keep a full charge for a long time |
they need
fewer cells in series and use less mounting space |
they are
less costly to replace |
they put out
higher voltages and require no maintenance |
|
D |
What is the
approximate voltage per cell produced by the nickel-iron (Edison)
battery? |
2.20 volts |
6.05 volts |
0.85 volts |
1.37 volts |
|
C |
Which of the
following statements concerning the specific gravity of a battery
electrolyte is true? |
The
temperature does not affect the specific gravity of the electrolyte. |
The most
accurate hydrometer reading is obtained immediately after water is
added. |
The specific
gravity reading is lowered when the electrolyte temperature has
increased. |
The
electrolyte becomes less dense when it is cooled. |
|
A |
What is a
hydrometer used to measure? |
specific
gravity of a battery electrolyte |
amount of
potable water a vessel is taking on |
power
developed by a salt water service pump |
water
pressure in a deck pipeline |
|
C |
Why should
battery rooms be well ventilated during the charging process? |
highly
poisonous gas is produced |
highly
combustible oxygen gas is produced |
highly
explosive hydrogen gas is produced |
corrosive
gases are produced |
|
D |
When a
hydrometer indicates specific gravity what is being compared? |
mass of
substance measured with the density of the same substance |
density of a
substance in water with the density of the same substance in air |
differences
in weight between water and the mass of the liquid being measured |
buoyancy of
the indicator in the liquid being measured as compared to water |
|
A |
When a
battery is continuously exposed to low temperatures, what is the best
procedure to keep it from freezing? |
keep the
battery fully charged |
disconnect
the battery |
remove the
battery caps |
securely
cover the battery |
|
C |
Why should a
breakable, mercury-filled thermometer NOT be used in a lead-acid
battery to measure electrolyte temperature? |
accidental
breakage can corrosion on the battery terminals |
accidental
breakage can cause rapid oxidation of battery plates |
accidental
breakage can cause severe sparking and explosions |
accidental
breakage can cause violent gassing at the positive plates |
|
A |
Under normal
conditions, storage batteries used for starting the emergency diesel
generator are maintained in a charged state by which of the following
methods? |
Trickle
charging |
Reverse
charging |
Fast
charging |
Equalizing
charge |
|
C |
What
practice would be considered proper storage battery maintenance? |
maintaining
a high charging rate at all times |
insuring
electrolyte level is below the separator plates |
applying
petroleum jelly on connections to minimize corrosion |
replacing
the electrolyte once a year |
|
B |
When
charging, which of the following represents the recommended maximum
allowable temperature for electrolyte in a lead-acid battery? |
212°F |
110°F |
145°F |
165°F |
|
A |
What should
be done when correcting specific gravity readings of a lead-acid
battery for existing temperature conditions? |
add 4
correction points for each 10°F the battery temperature is above 80°F |
subtract 4
correction points for each 10°F the battery temperature is above 80°F |
subtract 10
correction points for each 4°F the battery temperature is above 80°F |
add 10
correction points for each 4°F the battery temperature is above 80°F |
|
D |
What is the
most reliable indication of the state of charge of a lead-acid
battery? |
ampere-hour
capacity |
total cell
voltage |
individual
cell voltage |
electrolyte
specific gravity |
|
C |
What
statement is true concerning the specific gravity of the electrolyte
solution in a lead acid battery? |
the specific
gravity is not effected during charging |
the specific
gravity would read close to 1.830 when discharged |
the specific
gravity gives an indication of the state of charge of the battery |
the specific
gravity remains the same during discharge |
|
D |
What will
the charging of lead-acid storage batteries always result in? |
the danger
of lead poisoning |
local action |
dangerous
acid burns |
a
dangerously explosive gas being liberated |
|
A |
When
charging lead-acid batteries, why should you reduce the charging rate
as the battery nears its full charge capacity? |
to prevent
excessive gassing and overheating |
to increase
lead peroxide formation |
to reduce
lead sulfate deposits |
to allow
equalization of cell voltages |
|
A |
What is the
proper way to mix the electrolyte for a lead-acid battery? |
pour the
acid into the distilled water |
pour the
distilled water into the acid |
pour the
acid into the alkaline water |
pour the
alkaline water into the acid |
|
A |
When
charging a 100 amp-hour lead-acid battery, what statement is true? |
insure
adequate battery room ventilation |
always start
with a trickle charge rate |
insure that
violent gassing occurs |
insure that
the electrolyte level is below the top of the plates |
|
C |
Which of the
following statements concerning nickel-cadmium batteries is true? |
Nickel-cadmium batteries should only be discharged 50% before
recharging. |
When mixing
electrolyte always add acid to the water. |
The state of
charge cannot be determined by the specific gravity values. |
The
electrolyte of an idle nickel-cadmium battery must be replaced monthly
to maintain battery condition. |
|
B |
When a
nickel-cadmium battery begins gassing while connected to the battery
charging circuit, what should be done? |
add
distilled water to each cell to reduce the specific gravity of the
electrolyte |
do nothing
as this is a normal condition when charging |
add
potassium hydroxide to each cell to increase the specific gravity of
the electrolyte |
increase the
charging rate |
|
B |
What would
you use to determine the state of charge of a nickel-cadmium battery? |
ammeter |
voltmeter |
hydrometer |
potentiometer |
|
A |
Which
statement is true concerning the charging of a wet cell nickel-cadmium
battery? |
The specific
gravity of the electrolyte will be generally unaffected by the state
of charge. |
Extended
trickle charging should be avoided. |
add
distilled water just prior to charging to insure proper mixing |
The charging
rate should never allow gassing. |
|
D |
What could
cause a very slow, but continual loss of electrolyte level from the
cells of a storage battery? |
one or more
filler caps installed too tightly |
the specific
gravity being higher than normal |
too low a
charging rate |
evaporation
of the water |
|
C |
What would
cause a lead-acid battery to become hotter than normal during
charging? |
the specific
gravity is too high |
the battery
room door is secured |
excessive
charging current |
the charging
voltage is too low |
|
A |
When
troubleshooting a lead-acid storage battery, what is the best method
for detecting a weak or dead cell? |
comparing
the specific gravity of the electrolyte in each cell |
taking each
cell's temperature with a calibrated mercury thermometer |
visually
inspecting the electrolyte levels of each cell |
taking an
open circuit voltage test of individual cells |
|
C |
In terms of
the battery electrolyte, when performing maintenance of alkaline
batteries what should be done? |
checking the
electrolyte weekly using a hydrometer |
replacing
the electrolyte every 5 years |
wearing
protective gloves and goggles when handling electrolyte |
replacement
of the electrolyte when the volts per cell drops below 1.8 VDC |
|
C |
When
troubleshooting an alkaline storage battery, what is the best way to
locate a weak or dead cell? |
visually
inspecting each cell's electrolyte level |
measuring
the electrolyte temperature with an accurate mercury thermometer |
load testing
each cell with a voltmeter |
checking the
specific gravity of each cell |
|
C |
What is the
ampere-hour rating of a lead-acid battery that can deliver 20 amperes
continuously for 10 hours? |
20 |
40 |
200 |
400 |
|
C |
Three 12
volt, lead-acid, batteries connected in series will develop how many
volts? |
12 volts |
24 volts |
36 volts |
48 volts |
|
A |
As shown in
the illustration, the wet-cell storage batteries are connected in what
configuration? Illustration EL-0071 |
series |
parallel |
tandem |
compound |
|
A |
What is true
concerning the installation of batteries used for diesel engine
starting? |
be located
as close as possible to the engine |
be located
in a locker on the weather deck |
only be of
the nickel alkaline type |
have
sufficient capacity to provide at least 50 starts consecutively
without recharging |
|
A |
The
individual 12 volt lead-acid batteries, when connected as shown in the
illustration, as a battery bank would produce how many volts?
Illustration EL-0070 |
12 volts |
24 volts |
36 volts |
48 volts |
|
C |
Why should
battery rooms we well ventilated during the charging of storage
batteries? |
without
ventilation the battery will not take a full charge |
without
ventilation excessive gassing will occur |
highly
explosive gases will otherwise accumulate |
highly
poisonous gases are released |
|
D |
Which of the
following procedures represents the best method to prevent the
freezing of batteries continuously exposed to low temperatures? |
The battery
cap vents should be sealed. |
The battery
caps should be removed. |
The battery
should be disconnected from its charging source. |
The battery
should be kept in a fully charged condition. |
|
D |
Which of the
following statements describes the effects of ambient temperature on
local action within lead-acid storage batteries? |
At 90°F all
local action virtually ceases. |
Increasing
ambient temperature decreases local action. |
Ambient
temperature has no effect on local action. |
Increasing
ambient temperature increases local action. |
|
C |
As shown in
the cutaway view of the lead acid battery in figure "A" of the
illustration, if one half of the battery's cells are revealed by the
cutaway section (with the other half remaining hidden from view), what
is the nominal output voltage of the battery? Illustration EL-0031 |
6 volts |
7.5 volts |
12 volts |
18 volts |
|
B |
What is the
nominal open-circuit cell voltage of one lead-acid storage battery
cell? |
1.2 volts |
2 volts |
6 volts |
12 volts |
|
B |
To keep
emergency lead-acid batteries in a full state of charge for emergency
use, what is normally done? |
Batteries
are kept charged by performing an equalizing charge daily. |
Batteries
are kept charged by maintaining a continuous trickle charge. |
Batteries
are kept charged by maintaining the maximum charging rate. |
Batteries
are kept charged by cycling through discharge and charge cycles daily. |
|
C |
Assuming
that the electrolyte has had sufficient time to be uniformly diffused
throughout the cell, if the open-circuit cell voltage as measured by a
digital multimeter is 2.12, what would be the approximate specific
gravity? |
1.26 |
1.27 |
1.28 |
1.29 |
|
A |
The nominal
voltage of one cell of a wet cell nickel-cadmium battery is
approximately how many volts? |
1.2 volts |
1.5 volts |
2.0 volts |
3.0 volts |
|
C |
What
material are the plates of a wet cell NiCad storage battery made of? |
lead and
lead peroxide |
potassium
hydroxide with a small amount of sulfuric acid |
nickel
hydroxide and cadmium oxide |
silver oxide
and lead sulfate |
|
A |
Why are
nickel-cadmium batteries superior to lead-acid batteries for standby
service? |
they are
able to hold their charge for long periods of time without recharging |
they need
fewer cells connected in series for the same voltage and require less
mounting space |
the have
higher output voltages for the same number of cells and require no
maintenance |
they have a
lower cost of acquisition |
|
A |
What is the
approximate discharge voltage produced by one cell of a wet type
nickel-cadmium battery at 75% of charge? |
1.2 volts |
1.5 volts |
2.2 volts |
6.0 volts |
|
B |
What is the
most reliable and preferred method for determining the state of charge
of a wet-cell NiCad battery? |
Measuring
the specific gravity of each cell with a hydrometer. |
Measuring
the battery voltage with a digital voltmeter during charge or
discharge. |
Measuring
the battery voltage with a solenoid type voltage tester during charge
or discharge. |
Measuring
the temperature-corrected specific gravity of each cell with a
hydrometer and thermometer. |
|
D |
Which of the
listed battery charging circuits is used to maintain a wet-cell,
lead-acid, storage battery in a fully charged state during long
periods of disuse? |
High ampere
charging circuit |
Quick
charging circuit |
Normal
charging circuit |
Trickle
charging circuit |
|
B |
What will be
the freezing point of the electrolyte in a fully charged lead-acid
battery as compared to a discharged battery? |
the same as
in a discharged battery |
lower than
in a discharged battery |
higher than
in a discharged battery |
there is no
correlation between freezing point and the state of charge |
|
B |
What should
be performed as routine maintenance of lead acid batteries? |
conducting a
load test |
keeping the
terminals and connections clean and tight |
replacing
the electrolyte |
replacing
the plates and separators |
|
D |
Which of the
processes listed occurs during the charging of a lead-acid storage
battery? |
Both plates
change to lead peroxide. |
Lead
peroxide in the positive plates and sponge lead in the negative plates
change to lead sulfate. |
Both plates
change to sponge lead. |
Lead sulfate
is changed to lead peroxide in the positive plates and sponge lead in
the negative plates respectively. |
|
C |
To test the
state of charge of a nickel-cadmium battery, what should be used? |
hydrometer |
potentiometer |
voltmeter |
ammeter |
|
D |
Which of the
problems listed will occur if a lead-acid battery is allowed to remain
in a discharged condition for a long period of time? |
The
separators will harden. |
The
concentrated sulfuric acid will attack the lead peroxide plates. |
The
electrolyte will change to lead sulfate. |
The battery
may be unable to accept a full charge. |
|
C |
What is the
standard procedure for maintaining the charge in an emergency diesel
starting battery by trickle charge? |
whenever the
electrolyte specific gravity falls to 1.250 or lower |
at least
once each week |
continuously |
whenever the
charge falls to 75% of full charge |
|
B |
Which of the
substances listed should be applied to battery terminals to help
prevent corrosion? |
Zinc
chromate |
Petroleum
jelly |
Lead
peroxide |
Lead
hydroxide |
|
A |
What is
practice is considered conducting proper storage battery maintenance? |
keeping
connections tight and casing surfaces clean |
making sure
electrolyte level is below the separator plates |
insulating
the terminals with naval jelly |
maintaining
a high charging rate at all times |
|
A |
Which of the
problems listed will occur if a lead-acid battery is allowed to remain
in a discharged condition for a long period of time? |
The battery
may be unable to accept a full charge. |
The
electrolyte will change to lead sulfate. |
The
separators will harden. |
The
concentrated sulfuric acid will attack the lead peroxide plates. |
|
D |
What
condition associated with a lead-acid battery cell can cause the
plates to partially short-out and cause the cell to fail to hold a
charge. |
lime
accumulation on both the positive and negative terminal posts |
dirty or
acid-wet tops and sides of batteries |
sulfation of the plates due to consistent undercharging or leaving the
battery in a discharged
state |
accumulation
of sediment within the cells due to excessive overcharging and
discharging |
|
C |
What would
cause a lead-acid battery to become hotter than normal during
charging? |
the specific
gravity is too high |
the charging
voltage is too low |
excessive
charging current |
the battery
room door is secured |
|
B |
When
troubleshooting a lead-acid storage battery, what is the best method
for detecting a weak or dead cell? |
taking each
cell's temperature with a calibrated mercury thermometer |
comparing
the specific gravity of the electrolyte in each cell |
visually
inspecting the electrolyte levels of each cell |
taking an
open circuit voltage test of individual cells |
|
B |
To
facilitate communication between the wheelhouse and the steering gear
room in a steering emergency where no external source of power is
required, what means of two-way communication would be provided? |
Two-way
portable radios |
Sound-powered telephone system |
Ship-service
telephone system |
Emergency
loudspeaker system |
|
C |
Which
station's emergency loudspeaker must allow for two-way communication? |
Accommodation spaces station |
Crew's
quarters station |
Lifeboat
embarkation station |
Passenger
assembly station |
|
B |
Assuming the
vessel has an engine control room, where is an engineers'
assistance-needed alarm required to produce an audible signal? |
The crews'
and officers' mess |
The
engineers' accommodation spaces |
The
wheelhouse/navigational bridge |
The engine
room/machinery space |
|
B |
In a typical
fire detection control unit, what would be indicated by an illuminated
blue light? |
normal power
is on |
trouble in
the system |
fire or
smoke detected |
backup power
is on |
|
D |
Which of the
following fixed temperature heat-actuated fire detectors can be reused
after it has detected a fire? |
liquid
expansion |
thermostatic
cable |
fusible
metal |
bi-metallic
snap-disc |
|
D |
Which of the
following fixed temperature heat-actuated fire detectors is the most
prone to false alarms? |
fusible
metal detector |
liquid
expansion detector |
snap-action
bimetallic disc |
bimetallic
strip detector |
|
C |
What
shipboard system uses the synchronous transmission system? |
Turbocharger
RPM indicator system |
Shaft
revolution indicator system |
Rudder angle
indicator system |
Centrifuge
RPM indicator system |
|
B |
The shaft
revolution indicator system for a fixed pitch propeller has which of
the following display capabilities? |
Shaft RPM
and cumulative shaft revolutions only |
Direction of
rotation, shaft RPM, and cumulative shaft revolutions |
Direction of
rotation and shaft RPM only |
Propeller
pitch, shaft RPM, and cumulative shaft revolutions |
|
D |
A pyrometer
indicating system such as that used for measuring diesel engine
exhaust system temperatures uses what technology? |
externally-powered thermocouples |
externally
powered resistance temperature detectors |
self-powered
resistance temperature detectors |
self-powered
thermocouples |
|
A |
A bearing
temperature monitoring system such as that used for measuring selected
propulsion plant bearings uses what technology? |
externally-powered resistance temperature detectors |
externally-powered thermocouples |
self-powered
thermocouples |
self-powered
resistance temperature detectors |
|
C |
A salinity
indicator system such as that used to measure the salt content of
potable water systems and boiler feed and condensate systems uses what
technology? |
a salinity
cell that senses the pH of water |
a salinity
cell that senses the brine density of water |
a salinity
cell that senses the electrical conductivity of water |
a salinity
cell that senses the optical refraction of water |
|
D |
In a simple
DC circuit, the resistance is held constant while the applied voltage
is halved. What will be the effect on the current flow as compared to
the original current? |
double |
be divided
by four |
remain the
same |
be divided
by two |
|
A |
If the
voltage supplied to the lighting circuit is 110 volts, how much
current is drawn by a 100 watt light bulb? |
0.91 amps |
0.08 amps |
1.10 amps |
90.9 amps |
|
C |
An
electrical component is connected across a 120 volt 60 hertz AC
supply. What is the current drawn by the component if the impedance is
200 ohms? |
100 amperes |
0.01 amperes |
0.60 amperes |
1.67 amperes |
|
C |
What will be
the resulting current when a voltage of 115 VDC is applied to a
resistance of 12 ohms in figure "A" of the illustrated circuit with
the switch closed? Illustration EL-0018 |
1.24 amps |
127 amps |
9.58 amps |
104.34 amps |
|
D |
What will be
the resulting current when a voltage of 442.7 VDC is applied to a
resistance of 1.25 ohms in figure "A" of the illustrated circuit when
the switch is closed? Illustration EL-0018 |
35.32 amps |
28.25 amps |
443.62 amps |
354.16 amps |
|
D |
What will be
the resulting current when a voltage of 110 VDC is applied to a
resistance of 32 ohms in figure "A" of the illustrated circuit when
the switch is closed? Illustration EL-0018 |
142 amps |
.29 amps |
9.31 amps |
3.44 amps |
|
A |
What is the
current flow through R1 of the circuit in figure "B" of the
illustration with the switch closed if the resistance of R1 is 2 ohms,
R2 is 3 ohms and R3 is 6 ohms and the battery voltage is 12 VDC?
Illustration EL-0019 |
6 amps |
4 amps |
2 amps |
12 amps |
|
B |
What would
be the total current flowing in the circuit shown in figure "B" of the
illustration if the source is 30 volts, the resistance of R1 is 10
ohms, R2 is 10 ohms and R3 is 10 ohms, respectively? Illustration
EL-0032 |
15 amps |
2 amps |
5 amps |
1 amp |
|
A |
A lamp has a
source voltage of 110 volts and a current of 0.9 amps. What is the hot
resistance of the lamp filament? |
122.22 ohms |
0.008 ohms |
0.08 ohms |
12.22 ohms |
|
D |
What is the
total resistance of figure "B" of the illustrated circuit if the
resistance of R1 is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms?
Illustration EL-0020 |
1.5 ohms |
0.5 ohms |
1.28 ohms |
12 ohms |
|
A |
What is the
total resistance of the electrical circuit illustrated in figure "B"
if the resistance of R1 is 2 ohms, R2 is 4 ohms, and R3 is 4 ohms and
the battery voltage is 6 volts? Illustration EL-0019 |
1.00 ohms |
10.00 ohms |
0.01 ohms |
0.10 ohms |
|
A |
As shown in
figure "A" of the illustration if the applied voltage is 12 VDC, the
resistance of R1 is 10 ohms, and R2 is 10 ohms what is the current
flowing through R1 when the switch is closed? Illustration EL-0020 |
0.6 amp |
1.2 amps |
0.833 amp |
2.4 amps |
|
C |
In figure of
"A" of the illustrated circuit, what is the voltage measured across R1
if the battery voltage is 24 volts, the resistance of R1 is 34 ohms,
and the resistance of R2 is 126 ohms when the switch is closed?
Illustration EL-0020 |
18.9 volts |
150
millivolts |
5.1 volts |
24 volts |
|
B |
What is the
voltage across "R1" of figure "B" of the illustrated circuit with the
switch closed if the applied voltage is 24 volts and resistance of R1
is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms, respectively? Illustration
EL-0020 |
2 volts |
6 volts |
10 volts |
8 volts |
|
C |
A battery is
connected to a circuit containing three resistors in parallel. The
values of the three resistors are 2 ohms, 3 ohms, and 6 ohms. What is
the voltage of the battery if the total circuit current is 12 amps? |
2 volts |
6 volts |
12 volts |
24 volt |
|
C |
In the
illustration, 1, 2, 3 and 4 are 12 volt batteries. What will be the
nominal voltage as read by a voltmeter across the output of the
battery bank? Illustration EL-0107 |
12 volts |
48 volts |
24 volts |
6 volts |
|
D |
What would
be the voltage drop across the parallel branches of the circuit shown
in figure "B" of the illustration if the source voltage is 30 volts,
the resistance for R1 is 10 ohms, the resistance for R2 is 10 ohms and
the resistance for R3 is 10 ohms? Illustration EL-0032 |
5 volts |
20 volts |
30 volts |
10 volts |
|
A |
What would
be the terminal voltage and ampere-hour capacity of the battery bank
if each battery was rated at 50 amp-hours and 6 volts? Illustration
EL-0107 |
12 volts and
100 ampere-hours |
12 volts and
200 ampere-hours |
6 volts and
50 ampere-hours |
24 volts and
50 ampere-hours |
|
D |
If the
supply voltage is 220 volts 60 Hz, what is the operating voltage of
the motor controller control circuit illustrated in figure A of the
illustration? Illustration EL-0011 |
220 volts DC |
110 volts DC |
110 volts AC |
220 volts AC |
|
C |
How is the
power dissipated as heat in a direct current circuit calculated? |
E divided by
I |
I times R
divided by T |
I squared
times R |
P divided by
R |
|
B |
How many
watts of power is equal to one horsepower? |
500 watts |
746 watts |
663 watts |
1,000 watts |
|
B |
A
three-phase alternator operates at 450 volts with a 0.8 power factor.
If the ammeter indicates 250 amperes, what should be the kW meter
reading? |
194.85 kW |
155.70 kW |
127.27 kW |
90.00 kW |
|
A |
What is the
wattage of a heating element drawing a current of 30 amperes, at 120
volts? |
3600 watts |
360 watts |
99.97 watts |
30 watts |
|
B |
A 125 volt
DC motor is rated at 10 kW. What is the current rating of the motor? |
8.0 amps |
80 amps |
4.6 amps |
46.2 amps |
|
D |
What is the
power consumed by 'R2' in the circuit illustrated in figure "B", if
the applied voltage is 24 volts and the resistance of R1 is 3 ohms, R2
is 4 ohms, and R3 is 5 ohms, respectively? Illustration EL-0020 |
20 watts |
28 watts |
24 watts |
16 watts |
|
A |
Two 100 watt
light bulbs rated at 100 volts are connected in parallel across a 100
volt power supply. What will be the total power consumed by the two
bulbs? |
200 watts |
50 watts |
equal to the
product of the amperes times the voltage in each branch |
100 watts |
|
A |
What power
would be consumed by the series resistor in the circuit shown in the
illustration if the source is 30 volts, the resistance for R1 is 10
ohms, R2 is 10 ohms and R3 is 10 ohms? Illustration EL-0032 |
40 watts |
60 watts |
10 watts |
30 watts |
|
D |
In a 60 Hz
AC system, what is the duration in seconds for one complete cycle? |
1 second |
6 seconds |
60 seconds |
.016 of a
second |
|
A |
What is the
rotor speed of a six pole, 60 cycle, induction motor operating at full
load with 3% slip? |
1164 RPM |
3492 RPM |
1800 RPM |
1746 RPM |
|
A |
A four pole
turbo generator is used in conjunction with a 160 pole propulsion
motor. If the generator is turning at 3,200 RPM, what is the current
speed of the propeller? |
80 RPM |
60 RPM |
40 RPM |
100 RPM |
|
D |
What will be
the frequency of a three-phase, 16 pole, AC generator operating at
3000 revolutions per minute? |
90 hertz |
60 hertz |
180 hertz |
400 hertz |
|
D |
An AC
generator produces 60 Hz at 1800 RPM. If the generator speed is
increased to 1830 RPM, what will happen to the frequency in Hz? |
increase to
63 Hz |
decrease to
59 Hz |
remain at 60
Hz |
increase to
61 Hz |
|
C |
The turns
ratio of the step down transformer with dual voltage secondary as
shown in figure "B" of the illustration is two to one (total). If 440
volts were applied to terminals 'H1' and 'H2', what would be measured
across 'X1-X3' and 'X2-X4' assuming that the secondary windings are
connected in parallel? Illustration EL-0082 |
220 volts |
55 volts |
110 volts |
880 volts |
|
B |
A load is
connected across the secondary of the step up transformer shown in
figure "B" of the illustration and the current drawn by the load is 10
amps. If the turns ratio is 1 to 10 and the input voltage is 110 VAC,
what will be the current drawn by the primary? Illustration EL-0055 |
1000 amps |
100 amps |
1 amp |
10 amps |
|
A |
What is the
maximum allowable primary current of a 2 kVA step-down transformer
with a four to one turns ratio if the primary is connected across a
440 volt line? |
4.5 amps |
1.1 amps |
18.1 amps |
27.7 amps |
|
D |
In figure
"2" of the diagram shown in the illustration, the three phase power
transformer has a step-down turns ratio of four to one. If a
three-phase 440 volt supply is connected to terminals 'A1-B1-C'1, what
voltage should develop across terminals 'A2-B2-C2'? Illustration
EL-0084 |
762 volts |
64 volts |
190 volts |
110 volts |
|
A |
If it
becomes absolutely necessary to run an alternator at lower than 5%
below its rated frequency, in terms of output voltage, what must be
done? |
The
alternator output voltage must be decreased proportionately downward
with the frequency decrease. |
Under no
circumstances is it permissible to run an alternator at a frequency
lower than 5% below its rated frequency. |
The
alternator output voltage must be increased proportionately upward to
compensate for the frequency decrease. |
The
alternator output voltage must be maintained at the rated value for
the alternator output voltage. |
|
A |
Upon loss of
field excitation of a generator operating in parallel with others,
what must be done? |
The
parallel-connected generator which has suffered the loss of field
excitation must be immediately disconnected from the bus by tripping
its circuit breaker. |
The
parallel-connected generators still producing a voltage must have
their fields over-excited to compensate for the loss of field
excitation of the one generator. |
The
parallel-connected generator which has suffered the loss of field
excitation must have its prime mover immediately stopped. |
The
parallel-connected generator which has suffered the loss of field
excitation must have its prime mover immediately reduced to idle
speed. |
|
D |
Under
unusual circumstances, it may be required to operate a ship's service
generator above its rated kVA. What supplemental casualty control
action will be required? |
Increase the
cooling water flow, while maintaining air temperatures below the dew
point for increased cooling effect. |
While
maintaining the rated system voltage, lower the operating frequency to
at least 5% below the rated system frequency. |
While
maintaining the rated system frequency, lower the operating voltage to
at least 5% below the rated system voltage. |
Increase the
cooling water flow, while maintaining air temperatures above the dew
point to avoid any condensation. |
|
D |
When a
self-excited alternator's field has lost its residual magnetism due to
a prolonged idle period, it will fail to produce a voltage. Flashing
the field is the procedure used to restore the residual magnetism.
Using a 12 volt storage battery, how is this performed? |
The S+ and
S-leads are disconnected from the alternator stator. The S+ lead is
connected to the positive terminal of the battery, and the S-lead is
connected to the negative terminal. |
The S+ and
S-leads are disconnected from the alternator stator. The S+ lead is
connected to the negative terminal of the battery, and the S-lead is
connected to the positive terminal. |
The F+ and
F-leads are disconnected from the alternator field. The F+ lead is
connected to the negative terminal of the battery, and the F-lead is
connected to the positive terminal. |
The F+ and
F-leads are disconnected from the alternator field. The F+ lead is
connected to the positive terminal of the battery, and the F-lead is
connected to the negative terminal. |
|
C |
In the
illustrated one line diagram, if the ship's service generator on line
fails, what statement is true concerning the operation of the
emergency diesel generator? Illustration EL-0014 |
It must be
manually started but once running will automatically supply power to
the 450 VAC section of the emergency bus through the automatic bus
transfer device. |
It will
automatically start and automatically supply power to the 450 VAC
section of the main bus through the automatic bus transfer device. |
It will
automatically start and automatically supply power to the 450 VAC
section of the emergency bus through the automatic bus transfer
device. |
It will
automatically start but the automatic bus transfer device must be
manually shifted to 'Emergency Power' to supply the 450 VAC section of
the emergency bus. |
|
A |
As shown in
the illustrated one-line diagram of a two-tiered emergency power
system for a passenger ship, what statement is true? Illustration
EL-0166 |
On a loss of
normal ship's power, the temporary emergency loads power source is
battery (from AC/DC UPS "B"), whereas the final emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the final emergency loads power source is battery
(from AC/DC UPS "B"), whereas the temporary emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the final emergency loads power source is battery
(from AC/DC UPS "A"), whereas the temporary emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the temporary emergency loads power source is
battery (from AC/DC UPS "A"), whereas the final emergency loads power
source is the emergency generator. |
|
D |
Which figure
represents the schematic symbol shown in figure "2"? Illustration
EL-0034 |
figure "A" |
figure "C" |
figure "D" |
figure "B" |
|
D |
As shown in
figure "6" of the illustration, what does the symbol represent as used
in electrical drawings? Illustration EL-0026 |
maintaining
type push button with an electrical interlock |
normally
closed contact held open mechanically by an interlock |
limit switch
with one set of normally open contacts |
maintaining
type push button with a mechanical interlock |
|
C |
What does
the symbol labeled "OL" represent as shown in the power circuit on
lines T1 and T3 to the motor as shown in figure "A" of the
illustration? Illustration EL-0011 |
non-renewable fusible link |
overload
relay normally closed contacts |
overload
relay thermal heater |
overload
relay magnetic coil |
|
B |
Which of the
electronic schematic symbols represents the capacitor illustrated in
figure "2" of the illustration? Illustration EL-0015 |
D |
C |
A |
B |
|
C |
The
electrical diagram shown in figure "B" of the illustration represents
what type of DC motor? Illustration EL-0054 |
shunt-wound
DC motor |
permanent
magnet DC motor |
compound-wound DC motor |
series-wound
DC motor |
|
B |
Which of the
listed figures in the illustration represents a transformer configured
for single voltage primary and a tapped secondary? Illustration
EL-0055 |
E |
D |
A |
F |
|
A |
Which of the
illustrated resistors represents the schematic symbol shown in figure
"C"? Illustration EL-0021 |
figure "6" |
figure "10" |
figure "4" |
figure "7" |
|
A |
What is the
shape of the schematic symbol for an operational amplifier used in an
analog circuit? |
triangle |
circle |
square |
trapezoid |
|
B |
What is
statement is true in reference to reading electrical motor controller
elementary diagrams? |
circuits
subject to 500 volts or greater are drawn as light lines and below 500
volts as heavy
lines |
current
paths in the power circuit are drawn as heavy lines and in control
circuit as lighter lines |
current
paths in the control circuit are drawn as heavy lines and in the power
circuit as lighter lines |
circuits
subject to 500 volts or greater are drawn as heavy lines and below 500
volts as lighter lines |
|
B |
What type of
electrical diagram is shown in figure "B" of the illustration?
Illustration EL-0007 |
wiring
diagram |
schematic
diagram |
logic
diagram |
one line
diagram |
|
B |
Which of the
illustrated schematic symbols represents the type of switch pictured
in figure "F" of the illustration? Illustration EL-0026 |
6 |
3 |
2 |
1 |
|
D |
Which
electrical schematic symbol represents a normally open thermostat?
Illustration EL-0059 |
8 |
2 |
7 |
9 |
|
C |
Which of the
electrical schematic symbols represents a normally open limit switch?
Illustration EL-0059 |
5 |
7 |
12 |
13 |
|
C |
On vessels
with AC distribution systems, which of the following statements
represents the most difficult problem involved in obtaining a DC
potential suitable for use by computer components? |
Rectifiers
cannot operate with voltage regulators. |
A step-down
transformer is always required. |
The voltage
must be rectified and made ripple free. |
Vessel
vibrations affect the voltage source. |
|
B |
What
statement is true concerning read only memory (ROM)?
|
ROM is
volatile memory and the contents of ROM are not lost when the power is
removed. |
ROM is
non-volatile memory and the contents of ROM are not lost when the
power is removed. |
ROM is
non-volatile memory and the contents of ROM are lost when the power is
removed. |
ROM is
volatile memory and the contents of ROM are lost when the power is
removed. |
|
A |
What
statement is true concerning random access memory (RAM)? |
RAM is
volatile memory and the contents of RAM are lost when the power is
removed. |
RAM is
non-volatile memory and the contents of RAM are not lost when the
power is removed. |
RAM is
volatile memory and the contents of RAM are not lost when the power is
removed. |
RAM is
non-volatile memory and the contents of RAM are lost when the power is
removed. |
|
D |
Which of the
following devices represents primary storage, where the processor is
able to directly read instructions and data and directly return
results of its computation in fetch/execute cycles? |
Various
optical disks |
Hard disk
drive |
Magnetic
tape drive |
Random
access memory |
|
D |
Which of the
following data communication cable types offers the greatest immunity
to electromagnetic "noise"? |
Coaxial
(coax) |
Shielded
twisted pair |
Unshielded
twisted pair |
Fiber-optic |
|
A |
What type of
local area network physical topology features point-to-point
interconnection between all communicating devices and is the least
vulnerable to a break in communication? |
Mesh |
Bus |
Star |
Ring |
|
C |
Modern ships
use multiple computers arranged in a client/server network to perform
various shipboard functions. What type of computer network would most
likely be used aboard ship? |
Wireless
local area network |
Wireless
wide area network |
Wired local
area network |
Wired wide
area network |
|
D |
What
Ethernet cabling technology supports the greatest data transfer
speeds? |
Thick
Ethernet |
Fast
Ethernet |
Thin
Ethernet |
Gigabit
Ethernet |
|
B |
If an 8-bit
digital to analog converter (DAC) produces an analog output voltage
with a range of 10 volts (0-9 volts), what is the smallest incremental
step in voltage that can be generated at the output? |
0.03 volts |
0.04 volts |
0.625 volts |
1.25 volts |
|
C |
If a
computer display is flickering, how may this be remedied? |
Decease the
resolution bandwidth |
Increase the
resolution bandwidth |
Increase the
refresh rate |
Decrease the
refresh rate |
|
C |
As shown in
the illustration, what statement is true concerning each of the system
gateways? Illustration EL-0098 |
Each
connects one of two redundant automation area networks with both
redundant cargo process area networks. |
Each
connects one of two redundant automation area networks with both
redundant engine control process area networks. |
Each
connects one of two redundant automation area networks with one of two
redundant engine control process area networks and one of two
redundant cargo process area networks. |
Each
connects one of two redundant automation area networks with the other
automation area network. |
|
B |
As a DC
armature revolves within a stationary magnetic field, the reversals of
magnetization of the armature core lags the current reversals which
produces heat. What is the correct name for this action which is
minimized by the use of soft silicon steel? |
eddy-current
loss |
hysteresis
loss |
capacitive
reaction |
copper loss |
|
A |
Which of the
following losses is minimized by laminating the core of a DC generator
armature? |
Eddy current
loss |
Winding
copper loss |
IR drop loss |
Magnetic
hysteresis loss |
|
B |
What is the
correct name for a variable resistor wired in series with the shunt
field for the purposes of manually controlling generator output
voltage? |
bridge |
rheostat |
variable
shunt strip |
bleeder
resistor |
|
B |
In a
shunt-wound DC generator, with what generator component are the shunt
field windings connected in parallel with? |
the
compensating windings |
the armature
circuit |
the series
field winding |
the
interpoles |
|
C |
A variable
shunt, connected across the series field coils of a DC compound wound
generator, permits adjustment of the degree of compounding. What is
this variable shunt called? |
converter |
rheostat |
diverter |
divider |
|
D |
Which of the
following components are used to convert alternating current produced
in the DC generator armature windings to direct current? |
Armature and
equalizer |
Rotor and
interpoles |
Field and
exciter |
Commutator
and brushes |
|
A |
What is the
primary purpose of the brushes of DC generators? |
conduct
armature current to an external load |
provide
excitation to a DC generator |
neutralize
armature reaction |
convert DC
current to AC current |
|
C |
Why are
armature cores in a DC generator made of laminated steel sheets? |
fit the
curvature of the frame |
increase the
hysteresis effect |
reduce eddy
current losses |
allow for
easy assembly |
|
D |
Why are
modern DC generators fitted with commutating poles? |
they reduce
the load on the main poles |
they reduce
spring pressure on the brushes |
they prevent
motorizing |
they reduce
sparking |
|
D |
As shown in
the illustrated DC machine which is configured as a generator, what
type of machine is illustrated in terms of the configuration of the
windings? Illustration EL-0052 |
series wound |
cumulatively
compound wound |
differentially compound wound |
shunt wound |
|
C |
Which of the
diagrams shown in the illustration depicts the proper method of
aligning brushes on a commutator for a DC machine? Illustration
EL-0057 |
A |
B |
C |
D |
|
D |
As shown in
the illustration, which brush holder is of the reaction type?
Illustration EL-0029 |
1 |
2 |
3 |
4 |
|
C |
Which of the
following statements is true concerning the following illustration?
Illustration EL-0028 |
The figures
represent a basic AC generator |
Maximum
voltage is produced in figures A and C |
The figures
represent a basic DC generator |
Field
polarity reverses from figures A to B and C to D |
|
B |
By what
means is DC generator output voltage decreased? |
decreasing
armature resistance |
increasing
field resistance |
increasing
armature resistance |
decreasing
field resistance |
|
B |
Which of the
terms listed best describes a compound-wound DC generator having a
higher voltage at no load than at full load? |
Terminal
compounded |
Under
compounded |
Flat
compounded |
Over
compounded |
|
A |
What
function does an equalizing connection between two compound-wound DC
generators operating in parallel serve? |
parallel the
series fields of the generators |
reverse the
polarity of the incoming generator as the series field weakens |
reverse the
direction of current in the series field of the incoming generator |
automatically equalize the power factors |
|
C |
When two
generators are on the line and are both connected across a shared
load, how are they said to be operating? |
in resonance |
in frequency |
in parallel |
in series |
|
A |
Prior to
closing the circuit breaker when paralleling two DC generators, what
must you be certain of? |
voltage of
the incoming machine is at or slightly above the bus voltage |
synchroscope
needle is revolving slowly in the 'fast' direction |
frequency of
the incoming machine is slightly higher than the bus frequency |
current from
the incoming machine is the same as the bus current |
|
D |
By what
means is an AC generator prevented from becoming motorized? |
back
pressure trip |
over speed
trip |
governor
controls |
reverse
power relay |
|
D |
Brushes in a
DC generator must be positioned in the neutral plane to avoid
excessive sparking associated with the brushes. What device is used to
prevent the shifting of the neutral plane due to armature reaction for
varying generator loads __________. |
brushing
rigging |
field pole
windings |
armature
windings |
commutating
pole windings |
|
B |
To
effectively clean a commutator in good physical condition, what should
be used? |
trichloride
ethylene |
a canvas
wiper |
kerosene |
a commutator
stone |
|
A |
How may
propulsion DC motor brush pressures be calculated? |
dividing the
spring force by the brush contact area |
subtracting
the brush contact area from the spring pressure |
dividing the
brush contact area by the spring pressure |
subtracting
the spring pressure from the brush contact area |
|
B |
What can
cause uneven wear of the commutator surface on a direct current
generator? |
excessive
operation at light load |
incorrect
brush staggering |
rapid change
in load |
unequal pole
spacing |
|
A |
Hysteresis
is one cause of electrical power loss associated with electricity
generation equipment. What phenomenon results in hysteresis? |
heat
generated by magnetic polarity reversals |
arcing at
the brushes |
excessive
field current |
pulsating
terminal current |
|
C |
What may
cause brush sparking in a DC generator during commutation? |
eddy
currents in the armature core |
excessive
brush pressure |
misalignment
of the brush rigging |
hysteresis
in the armature core |
|
D |
On vessels
with AC distribution systems, which of the following statements
represents the most difficult problem involved in obtaining a DC
potential suitable for use by computer components? |
Rectifiers
cannot operate with voltage regulators. |
A step-down
transformer is always required. |
Vessel
vibrations affect the voltage source. |
The voltage
must be rectified and made ripple free. |
|
B |
What
statement is true concerning read only memory (ROM)?
|
ROM is
non-volatile memory and the contents of ROM are lost when the power is
removed. |
ROM is
non-volatile memory and the contents of ROM are not lost when the
power is removed. |
ROM is
volatile memory and the contents of ROM are not lost when the power is
removed. |
ROM is
volatile memory and the contents of ROM are lost when the power is
removed. |
|
A |
What
statement is true concerning random access memory (RAM)? |
RAM is
volatile memory and the contents of RAM are lost when the power is
removed. |
RAM is
non-volatile memory and the contents of RAM are lost when the power is
removed. |
RAM is
volatile memory and the contents of RAM are not lost when the power is
removed. |
RAM is
non-volatile memory and the contents of RAM are not lost when the
power is removed. |
|
B |
Which of the
following devices represents primary storage, where the processor is
able to directly read instructions and data and directly return
results of its computation in fetch/execute cycles? |
Various
optical disks |
Random
access memory |
Hard disk
drive |
Magnetic
tape drive |
|
A |
Which of the
following data communication cable types offers the greatest immunity
to electromagnetic "noise"? |
Fiber-optic |
Unshielded
twisted pair |
Coaxial
(coax) |
Shielded
twisted pair |
|
A |
What type of
local area network physical topology features point-to-point
interconnection between all communicating devices and is the least
vulnerable to a break in communication? |
Mesh |
Star |
Bus |
Ring |
|
A |
Modern ships
use multiple computers arranged in a client/server network to perform
various shipboard functions. What type of computer network would most
likely be used aboard ship? |
Wired local
area network |
Wireless
local area network |
Wireless
wide area network |
Wired wide
area network |
|
A |
What
Ethernet cabling technology supports the greatest data transfer
speeds? |
Gigabit
Ethernet |
Fast
Ethernet |
Thick
Ethernet |
Thin
Ethernet |
|
B |
If an 8-bit
digital to analog converter (DAC) produces an analog output voltage
with a range of 10 volts (0-9 volts), what is the smallest incremental
step in voltage that can be generated at the output? |
0.03 volts |
0.04 volts |
0.625 volts |
1.25 volts |
|
C |
If a
computer display is flickering, how may this be remedied? |
Decease the
resolution bandwidth |
Increase the
resolution bandwidth |
Increase the
refresh rate |
Decrease the
refresh rate |
|
D |
According to
the liquid crystal data display for the depth sounder shown in the
illustration, what is the instantaneous depth currently being
displayed? Illustration EL-0186 |
43.5 meters
below the surface |
43.5 meters
below the transducer |
47.5 meters
below the surface |
47.5 meters
below the transducer |
|
D |
Using the
trouble analysis chart and faults table provided in the illustration,
if the gyrocompass was malfunctioning, but no fault codes are present
on the display unit, what is most likely the problem if the DC/DC
converter LED status indicator is functioning properly, but the CPU
LED status indicator is not blinking? Illustration EL-0195 |
The AC/DC
power supply is malfunctioning. |
Ship's power
is not available. |
The DC/DC
converter is malfunctioning. |
The CPU
assembly is malfunctioning. |
|
D |
In mounting
a transducer for a depth sounding system, what would represent an
ideal location? |
Mount the
transducer aft of the position where the bow wave re-enters the sea. |
Mount the
transducer close to propellers but far away from sea water hull outlet
openings. |
Mount the
transducer far away from propellers but close to sea water hull outlet
openings. |
Mount the
transducer forward of the position where the bow wave re-enters the
sea. |
|
A |
In viewing
the liquid crystal display for the illustrated depth sounder data
display unit, what should be done if the graphic display of the ocean
bottom is no longer visible on the screen? Illustration EL-0186 |
Increase the
range adjustment. |
Decrease the
range adjustment. |
Decrease the
gain adjustment. |
Increase the
gain adjustment. |
|
A |
As shown in
the illustrated block diagram for a digitized echo sounding system,
what statement is true concerning the transmission and reception of
acoustical energy? Illustration EL-0185 |
The
acoustical energy is produced as rapid, short high intensity pulses
and transmitted from the transducer and the reflected acoustical
energy is received by the same transducer. |
The
acoustical energy is produced as a continuous wave and transmitted
from one transducer and the reflected acoustical energy is received by
a second transducer. |
The
acoustical energy is produced as a continuous wave and transmitted
from the transducer and the reflected acoustical energy is received by
the same transducer. |
The
acoustical energy is produced as rapid, short high intensity pulses
and transmitted from one transducer and the reflected acoustical
energy is received by a second transducer. |
|
C |
As shown in
the illustrated block diagram for a digitized echo sounding system,
what statement is true concerning the function of the transducer?
Illustration EL-0185 |
The
transducer converts radio frequency (RF) electromagnetic energy to
acoustical energy while receiving and converts the reflected
acoustical energy back into RF electromagnetic energy while
transmitting. |
The
transducer converts audio frequency (AF) electromagnetic energy to
acoustical energy while receiving and converts the reflected
acoustical energy back into AF electromagnetic energy while
transmitting. |
The
transducer converts radio frequency (RF) electromagnetic energy to
acoustical energy while transmitting and converts the reflected
acoustical energy back into RF electromagnetic energy while receiving. |
The
transducer converts audio frequency (AF) electromagnetic energy to
acoustical energy while transmitting and converts the reflected
acoustical energy back into AF electromagnetic energy while receiving. |
|
D |
As shown in
the illustrated graph showing the effect of overshoot on steering
system control stability, what statement is true? Illustration EL-0188 |
The dead
band is approximately 8 degrees and the control system is inherently
stable. |
The dead
band is approximately 20 degrees and the control system is inherently
unstable. o |
The dead
band is approximately 12 degrees and the control system is inherently
unstable. |
The dead
band is approximately 8 degrees and the control system is inherently
unstable. |
|
C |
As shown in
the illustrated adaptive digital steering control system functional
block diagram and listed system interface signals table, what would
the rudder order signal output voltage to the rudder servo amplifier
be for a rudder order of 15 degrees right rudder? Assume that left
rudder order signals are negative in polarity and that right rudder
order signals are positive in polarity. Illustration EL-0191 |
-1.33 VDC |
-3.75 VDC |
+3.75 VDC |
+5.0 VDC |
|
C |
As shown in
the illustrated adaptive digital steering control system functional
block diagram and listed system interface signals table, what would
the rudder order signal output voltage to the rudder servo amplifier
be for a rudder order of 20 degrees left rudder? Assume that left
rudder order signals are negative in polarity and that right rudder
order signals are positive in polarity. Illustration EL-0191 |
-2.25 VDC |
-4.0 VDC |
-5.0 VDC |
+5.0 VDC |
|
C |
As shown in
the illustrated digital gyrocompass functional block diagram and the
associated communications protocols table, what would the rate of turn
signal voltage be if the rate of turn is 30 degrees per minute to
port? Assume that the rate of turn to port signal voltage is negative
in polarity and that the rate of turn to starboard signal voltage is
positive in polarity. Illustration EL-0194 |
-0.5 VDC |
-1.0 VDC |
-1.5 VDC |
+1.5 VDC |
|
B |
Which of the
following statements concerning electrical cables is correct?
|
Electric
cable coverings should never be grounded. |
Where they
pass through watertight bulkheads, they should be fitted with
watertight stuffing boxes. |
Electrical
cables must be glued in place where nonmetallic insulation is used. |
Electrical
cables must be rigidly held in place by welding of armored cable. |
|
C |
What is a
common type of protective covering used on electrical conductors? |
plain paper |
silver
sheathing |
rubber or
plastic |
Babbitt
sheathing |
|
C |
Why is
copper often used as an electrical conductor? |
has high
resistance at low temperatures |
has a highly
polished surface |
is able to
pass current with little opposition |
holds
insulation together well |
|
A |
What is the
reason that some electric cables are formed of stranded wire? |
stranded
wire increases their flexibility over solid wire and reduces skin
effect losses |
stranded
wire increases the current carrying capability for a given size wire |
stranded
wire decreases the weight for a given size wire |
stranded
wire assures good conductivity at junction points |
|
B |
Why are
large cable sizes often formed as individual conductors comprised of
several smaller strands? |
reduce the
resistance to current flow for a given wire size |
obtain the
flexibility required for easy handling and reduces skin effect losses |
reduce the
overall weight of the wire run |
reduce the
number of supports needed for a horizontal overhead run |
|
B |
Which of the
following characteristics is most critical in determining the wire
gauge size of the cable to be used in a particular circuit? |
voltage
rating |
current
rating |
inductance
per unit length |
weight per
unit length |
|
B |
The 24 volt
DC bus on the emergency switchboard is used to supply power to what
system or equipment? |
main
lighting system |
general
alarm and vital communication systems |
propulsion
engine lube oil pump motors |
steering
gear power unit motors |
|
A |
In the
illustrated one line diagram, if the ship's service generator on line
fails, what statement is true concerning the operation of the
emergency diesel generator? Illustration EL-0014 |
It will
automatically start and automatically supply power to the 450 VAC
section of the emergency bus through the automatic bus transfer
device. |
It must be
manually started but once running will automatically supply power to
the 450 VAC section of the emergency bus through the automatic bus
transfer device. |
It will
automatically start but the automatic bus transfer device must be
manually shifted to 'Emergency Power' to supply the 450 VAC section of
the emergency bus. |
It will
automatically start and automatically supply power to the 450 VAC
section of the main bus through the automatic bus transfer device. |
|
B |
As shown in
figure "B" of the illustration, with respect to the common equipment
grounding conductor, what statement is true? Illustration EL-0125 |
The common
equipment grounding conductor is insulated from the source and this is
the least common arrangement onboard merchant vessels. |
The common
equipment grounding conductor is solidly-grounded at the source and
this is the least common arrangement onboard merchant vessels. |
The common
equipment grounding conductor is insulated from the source and this is
the most common arrangement onboard merchant vessels. |
The common
equipment grounding conductor is solidly-grounded at the source and
this is the most common arrangement onboard merchant vessels. |
|
A |
As shown in
the illustration, which of the following pieces of equipment is
provided with a remote pushbutton station? Illustration EL-0165 |
Cargo Oil
Transfer Pump No. 1 |
Sewage
Treatment Plant |
Lube Oil
Service Pump No. 1 |
S.W. Cooling
Circ. Pump No. 1 |
|
A |
As shown in
the illustrated one-line diagram of a two-tiered emergency power
system for a passenger ship, what statement is true? Illustration
EL-0166 |
On a
restoration of normal ship's power, the final and temporary emergency
loads power source is from the main switchboard. |
On a
restoration of normal ship's power, the temporary emergency loads
power source is battery (from AC/DC UPS "A"), whereas the final
emergency loads power source is from the main switchboard. |
On a
restoration of normal ship's power, the final emergency loads power
source is battery (from AC/DC UPS "B"), whereas the temporary
emergency loads power source is from the main switchboard. |
On a
restoration of normal ship's power, the final emergency loads power
source is from the main switchboard, whereas the temporary emergency
loads power source is battery (from AC/DC UPS "B"). |
|
B |
Which of the
illustrated safety disconnect switches represents a double throw
switch? Illustration EL-0176 |
A and B |
B and D |
A and D |
C and D |
|
C |
How are
fuses rated? |
voltage and
amperage only |
interrupting
capacity only |
voltage,
amperage, and interrupting capacity |
amperage
only |
|
A |
How would a
circuit with a blown fuse be described? |
an open
circuit |
a bonded
circuit |
a grounded
circuit |
a short
circuit |
|
A |
For what
purpose are time delayed or delayed action-type fuses used? |
permit
momentary overloads without melting |
prevent
opens in motor circuits |
guard
lighting and electronic circuits |
prevent
grounds in branch circuits |
|
D |
Which of the
following precautions should be taken when a blown fuse, rated at 10
amperes, is replaced? |
Fuses of 10
ampere rating and less are virtually harmless when energized and may
be handled freely. |
Use
needle-nose pliers to remove fuse from the circuit. |
Short out
the fuse before removing it from the circuit. |
Replace
blown fuse with one of equal voltage and ampere capacity. |
|
C |
What is the
characteristic that is associated with an "instantaneous-trip"
single-element type fuse? |
opens a
circuit by using a time delay element with a magnetic trip |
allows a
preset delay between over current and melting |
opens as
soon as the load current exceeds its set point |
resets
itself when the over current is corrected |
|
C |
In a dual
element time-delay cartridge-type fuse, what type of protection is
provided for motor applications? |
short-circuit protection using a spring loaded soldered joint AND
sustained overload protection using a fusible link |
sustained
overload protection using a spring loaded soldered joint only |
short-circuit protection using a fusible link AND sustained overload
protection using a spring loaded soldered joint |
short-circuit protection using a fusible link only |
|
A |
A
thermal-magnetic circuit breaker for a 300 KW alternator is rated at
500 amperes at full continuous load. Which of the following conditions
will trip the breaker? |
Instantaneous current draw of 5,000 amperes. |
Sustained
current draw of 500 amperes for 10 minutes. |
Sustained
current draw of 450 amperes for 2 hours. |
Momentary
current draw of 1000 amperes for 3 seconds. |
|
D |
By what
means does a molded-case circuit breaker provide protection against
short circuits? |
use of an
arc quencher |
use of a
shading coil |
use of a
bimetallic strip |
use of a
magnetic trip unit |
|
B |
By what
means is protection against sustained overloads occurring in
molded-case circuit breakers provided? |
a magnetic
trip unit |
a thermal
trip unit |
a reverse
current relay |
an
overvoltage release |
|
D |
How does a
circuit breaker differ from a fuse? |
a circuit
breaker melts and must be replaced, a fuse does neither |
a circuit
breaker gives no visual indication of having opened the circuit, a
fuse universally does |
a circuit breaker is enclosed in a tube of insulating material with
metal ferrules at each end, a
fuse is not |
a circuit
breaker trips to break the circuit and may be reset, a fuse may not be
reset |
|
B |
How will a
molded-case circuit breaker with a thermal trip unit react immediately
after it has tripped, as a result of an overloaded motor circuit? |
The breaker
handle will lock in the OFF position. |
The breaker
cannot be reset to the ON position until the thermal element cools
down. |
The breaker
handle will lock in the TRIPPED position. |
The thermal
element must be replaced after an overload trip has occurred before it
can be restored into service. |
|
A |
When the
operating handle of a molded-case circuit breaker is in the
mid-position, what is the indication for the position of the circuit
breaker? |
in the
'tripped' position |
in the
'closed' position |
in the
'opened' position |
in the
'reset' position |
|
A |
The arc
resulting from the tripping of a circuit breaker is prevented from
damaging the contacts. How is this done? |
directing
the arc into an arc chute |
designing
the contacts to open slowly |
instantaneous magnetic trip for overload currents |
an inverse
timed thermal trip for short circuit currents |
|
D |
Under
voltage trips are frequently installed on switchboard circuit breakers
for what reason? |
trip out
generators in the event of severe arcing or sparking |
trip out the
breaker if the generator over speeds by 5%, but continues to run |
trip out
generators when there is reversal of power in the main circuit |
trip out the
generator when there is insufficient voltage being delivered to
distribution circuits |
|
A |
How can a
motor be protected from overheating due to sustained motor overload? |
thermal
circuit breaker |
quick-acting
fuse |
magnetic
circuit breaker |
single
element fuse |
|
D |
In figure
"1" of the illustration, what are the trip characteristics associated
with this type of circuit breaker? Illustration EL-0033 |
inverse-time
delay characteristic for short-circuit protection |
instantaneous trip characteristic for short-circuit protection |
instantaneous trip characteristic for sustained overloads |
inverse-time
delay characteristic for sustained overloads |
|
D |
How is
electrical conductor insulation classed? Example: insulation class H |
conductor
opacity |
conductor
current carrying capacity |
voltage
rating of the insulation |
limiting
internal hot spot temperature |
|
C |
Which of the
following materials is a good electrical insulator? |
copper |
silver |
wood |
gold |
|
A |
As shown in
the illustration, the change-over switch is what type of device?
Illustration EL-0058 |
double-pole,
double-throw switch |
double-pole,
single-throw switch |
single-pole,
single-throw switch |
single-pole,
double-throw switch |
|
A |
As shown in
the illustration, what are the characteristics of the trouble relay
contacts? Illustration EL-0058 |
two sets of
normally closed contacts which open when the trouble relay coil is
energized |
two sets of
normally closed contacts which close when the trouble relay coil is
energized |
two sets of
normally open contacts which close when the trouble relay coil is
energized |
two sets of
normally open contacts which open when the trouble relay coil is
energized |
|
C |
Besides the
fluorescent lamp itself and possibly a starter, which of the following
components is included in a fluorescent lighting fixture? |
Magnetron |
Laser |
Ballast
(choke coil) |
Magnetic
resonator |
|
B |
What type of
circuit is represented by the diagram shown in the illustration?
Illustration EL-0058 |
common
fluorescent lighting circuit |
navigation
running light circuit |
dual speed,
2-winding motor controller circuit |
uninterruptible power supply circuit |
|
A |
As shown in
the illustration, what event would give the same indication that would
occur when a stern light circuit fuse blows open? Illustration EL-0058 |
stern light
"2" burns out |
stern light
trouble lamp burns out |
trouble
buzzer coil open circuits |
trouble
relay normally closed contacts open |
|
B |
Which of the
listed types of lighting fixtures does the diagram shown in figure "A"
of the illustration represent? Illustration EL-0081 |
High
pressure mercury fluorescent |
Low pressure
mercury fluorescent |
High
pressure sodium |
Low voltage
quartz |
|
D |
What is the
functional purpose component "5" as shown in figure "B" of the
illustration? Illustration EL-0081 |
to rapidly
strike the arc to fire the tube nearly instantly after the lighting
fixture switch is closed |
provide
power factor correction |
regulate the
current drawn by the fluorescent tube once the arc has been stricken |
initially
heat the fluorescent tube filaments at startup and cause the ballast
to strike the arc to fire the tube after warm-up |
|
C |
What is the
purpose of the capacitor within component "5" of the circuit shown in
figure "B" of the illustration? Illustration EL-0081 |
counteract
the inductive reactance in the circuit |
discharge
the neon within the envelope |
prolong the
life of the component's contacts |
store power
to operate the circuit should "D" open |
|
B |
Incandescent
lamps are classified according to the shape of the bulb and the type
of service, as well as the size and style of the base. How are
incandescent lamps rated? |
operating
reactance |
operating
voltage and wattage |
operating
frequency and impedance |
operating
resistance |
|
D |
As shown in
the illustration, which of the lighting fixtures represents an
incandescent bulb? Illustration EL-0122 |
C |
D |
A |
B |
|
A |
What is a
purpose of the automatic bus transfer device shown in the
illustration? Illustration EL-0014 |
Provide
power to the 450 VAC emergency bus from the emergency generator in the
emergency mode. |
Provide
power to the 450 VAC emergency bus from the 450 VAC main bus in the
emergency mode. |
Provide
power to the 450 VAC main bus from the 450 VAC emergency bus in the
emergency mode. |
Provide
power to the 450 VAC main bus from the emergency generator in the
emergency mode. |
|
A |
What
statement is true concerning a ground in an 450 VAC electrical circuit
outside the engine room? |
It is
indicated by the ground detecting lamps on the main switchboard. |
It cannot be
detected under normal conditions. |
It is of no
consequence to engineering personnel. |
It is
indicated at the branch circuit breaker panel. |
|
B |
When will
the timer element of a reverse power relay activate the relay? |
the power
flow is the opposite to the tripping direction |
the power
flow is the same as the tripping direction |
the movement
of the disk is damped by a permanent magnet |
the load
difference between generators is more than 10 percent. |
|
B |
What is a
bus disconnect link used to isolate? |
positive and
negative buses from the neutral |
the
generator circuit breaker from the bus |
different
bus phases from the equalizer connection |
one bus bar
from the ground detection system |
|
B |
Capacitors
can be used in electric distribution systems to improve power factor.
This is accomplished by seesawing energy between the capacitor and
what device or devices? |
capacitive
loads |
inductive
loads |
generator |
resistive
loads |
|
A |
Which of the
following represents a characteristic of an ungrounded electrical
distribution system? |
Accidental
contact between one line and ground does not cause an outage. |
Double
ground faults on different phases will not cause an outage. |
Ground
detection systems are unnecessary. |
Accidental
contact between one line and ground will always cause an outage. |
|
B |
Ammeters and
voltmeters used in sinusoidal AC power systems indicate which of the
following values of the waveforms measured? |
Maximum
value |
Root-mean-square value |
Peak value |
Average
value |
|
A |
What is a
wattmeter used to measure and indicate? |
the power
being consumed by electrical equipment |
partial
circuit resistance |
voltage
existing between two points in a circuit |
current
flowing in a circuit |
|
C |
The true
power indicated by a wattmeter depends on the current flow through the
load, the magnitude of the voltage across the load, and what other
factor? |
inertia of
the movable coil |
angle of
coil displacement |
power factor
of the load |
high
resistance from the load |
|
B |
How are the
line losses in a distribution circuit kept to a minimum? |
using higher
current and lower voltage |
using higher
voltage and lower current |
adding
rubber insulation conductors to the circuit |
increasing
the number of thermal relays in the circuit |
|
A |
What is
meant by a 'dead front' switchboard? |
a
switchboard with insulated switches and no exposed terminals |
a
switchboard without safety hand rails nor rubber mats |
a
switchboard without circuit breakers |
a
switchboard without switches on it |
|
D |
What is the
name of the part of the shipboard electrical system used to control
the distribution of power to the branch circuits? |
disconnect
links |
bridge
control panel |
governor
relay box |
main
switchboard |
|
C |
In
comparison to a main switchboard for a DC electrical distribution
system, a main switchboard for an AC electrical distribution system
requires the use of which of the following devices, whereas a DC main
switchboard does not? |
Voltage
regulator and prime mover governor speed controls |
Reverse
power or current relays |
Frequency
meter, power factor or reactive power meters, and synchronizing lamps
or synchroscope |
Generator
and load center circuit breakers |
|
C |
Which of the
following is a pictured three phase power transformer, usually used to
step down line voltage for supplying reduced voltage lighting
circuits? Illustration EL-0177 |
B |
A |
D |
C |
|
A |
When a low
input voltage is delivered to a transformer which then produces a high
output voltage, what is the proper name for the transformer type? |
step-up
transformer |
primary
transformer |
step-down
transformer |
secondary
transformer |
|
B |
Which of the
following statements is true concerning step-down transformer
operation? |
The voltage
supplied to the primary side is lower than the voltage produced by the
secondary side. |
The voltage
supplied to the primary side is greater than the voltage produced by
the secondary side. |
The kVA
consumed by the primary side is greater than the kVA produced by the
secondary side. |
The current
drawn by the primary side is greater than the current delivered from
the secondary side. |
|
D |
What will
happen to the primary winding when the load increases on the secondary
windings of a transformer? |
There will
be a decrease in the primary current. |
There will
be an increase in the primary voltage. |
There will
be a decrease in the primary voltage. |
There will
be an increase in the primary current. |
|
D |
When a
transformer is used to step down voltage, what statement is true? |
The low
voltage winding is part of the core. |
The low
voltage winding is the primary coil. |
The low
voltage winding is not insulated. |
The low
voltage winding is the secondary coil. |
|
D |
Which of the
following statements describes the difference between the primary
windings and the secondary windings of a 2:1 step-down voltage
transformer? |
The
secondary windings can only provide half as much current as the
primary windings. |
The
secondary windings have twice as much resistance as the primary
windings. |
The
secondary windings use smaller wires than the primary windings. |
The
secondary windings have half as many turns as the primary windings. |
|
D |
What is the
primary purpose associated with the use of transformers onboard ships
with AC generators? |
increase
power output to modulating frequency controllers |
change line
frequency value |
decrease
power output to modulating frequency controllers |
provide
different voltage values to operate various types of electrical
equipment. |
|
C |
An
autotransformer is equipped with a 50% tap, a 65% tap, and an 80% tap.
Which of the following statements is true concerning a load connected
to the 50% tap? |
The load is
receiving two times line voltage and drawing two times line current. |
The load is
receiving two times line voltage and drawing one half of line current. |
The load is
receiving one half of line voltage and drawing two times line current. |
The load is
receiving one half of line voltage and drawing one half of line
current. |
|
D |
What is the
basic operating principle of a transformer in terms of producing a
voltage? |
self-inductance |
hysteresis |
eddy
currents |
mutual
inductance |
|
D |
Which of the
listed figures shown in the illustration represents a three phase
transformer connected in a wye-delta configuration? Illustration
EL-0084 |
1 |
2 |
3 |
4 |
|
D |
When working
on a high voltage circuit, you should always have another person
present with you. This person should have a good working knowledge of
the hazards associated with working on high voltage electrical
circuits as well as the first aid techniques for treating electrical
shock. What other knowledge is essential? |
detailed
knowledge of insulation dielectric strengths associated with the
circuit being worked on |
working
knowledge of the conductor ampacities associated with the circuit
being worked on |
detailed
knowledge of the insulation voltage ratings associated with circuit
being worked on |
working
knowledge of the circuit being worked on and all means of isolation
and grounding |
|
A |
What is the
proper way to apply plastic electrical tape to an electric cable
splice? |
wind the
tape so that each turn overlaps the turn before it |
apply tape
to the braided cover, but avoid touching it |
apply the
tape in one non-overlapping layer only |
heat the
tape with a soldering iron for good bonding |
|
D |
When working
on electrical circuits containing large capacitors, in addition to
de-energizing the circuit, which of the listed precautions should also
be taken? |
Measure
capacitor insulation resistance. |
Keep all
radio equipment away. |
Check
capacitor circuit polarity. |
Discharge
the capacitor through a 50,000 ohm resistor. |
|
B |
Which of the
following statements represents the FIRST precaution to be taken prior
to working on any installed electrical component? |
Ground the
case of the machine before beginning any repairs. |
Open the
supply circuits and tag the switches. |
Use only
approved non-conducting tools. |
Wear rubber
gloves and boots. |
|
D |
When
changing fuses, what safety precaution should be taken? |
wear safety
glasses |
stand on a
rubber mat |
wear rubber
boots |
use a fuse
puller |
|
D |
When
replacing fuses, what practice should be observed? |
to stand on
a rubber mat and use rubber gloves |
to increase
the fuse rating 10% to guard against 'nuisance blowing' |
to use
insulated pliers or screwdriver |
the fuse
clips are straight, tight, and in good contact |
|
A |
What device
can be used to check the calibration of a circuit breaker? |
portable low
voltage high current testing unit |
clamp-on
voltmeter |
500 volt
megohmmeter |
standard
digital multimeter |
|
D |
What should
be done when performing maintenance of circuit breaker contacts? |
smooth
roughened contact surfaces with a file |
apply a thin
film of oil on contact surfaces |
use a
metallic oxide abrasive cloth to dress contacts |
inspect for
wear and misalignment of main contacts |
|
B |
As shown in
the illustration, what maintenance would be required of the circuit
components? Illustration EL-0058 |
Change out
the individual navigation light circuit fuses monthly. |
Clean the
glass surrounding the individual navigation lights as needed. |
File the
points of the buzzer contacts every six months. |
Take megger
readings on the navigation lights quarterly. |
|
A |
In order to
safely carry out repairs to a generator circuit breaker, it must be
isolated from the bus. How is this accomplished? |
opening the
bus disconnect links |
opening the
generator bus fuse connections |
opening the
reverse current relay |
opening the
reverse power relay |
|
D |
What should
be included in the performance of routine maintenance of dry-type
transformers? |
measuring
and recording the winding temperature with an accurate mercury
thermometer |
making sure
that the units are close to bulkheads or corners to protect them from
damage |
periodic
cleaning of the winding insulation with an approved solvent |
cleaning the
windings, if accessible, with a vacuum cleaner or very low pressure
air |
|
B |
When
replacing a defective transformer in a paralleled transformer
configuration, which of the following actions must be carried out to
insure proper operation of the equipment it serves? |
The iron
core of the transformer must be flashed to pre-magnetize it. |
The
transformer connections must be made as before with regard to the
indicated polarity. |
The
secondary leads must be grounded for 10 minutes to remove static
charges. |
The iron
core must be grounded for 10 minutes to remove any residual magnetism. |
|
A |
The FIRST
requirement for logical troubleshooting of any system requires the
troubleshooter to do what? |
recognize
what is normal operation |
isolate the
faulty component |
identify the
probable cause of a symptom |
collect all
available data on a casualty |
|
B |
Multiple
grounds have developed and were initially indicated by the
ground-detecting system as one ground. What is the FIRST step in
locating the grounds? |
change over
generators |
eliminate
the individual circuits one by one until the ground detecting system
no longer indicates any grounds |
check each
circuit with a megohmmeter |
examine the
main bus bars for signs of overheating |
|
D |
When
maintenance personnel are working on electrical equipment, all supply
switches should be secured in the open position and tagged. Who
specifically should perform the lock-out/tag-out procedure? |
chief
electrician |
chief
engineer or first assistant |
watch
engineer |
person
performing the repair |
|
A |
Why must
accidental grounds in a shipboard electrical system must be repaired
as soon as possible? |
they may
damage insulation and may cause power outages |
they will
overload the ground detection system |
they will
result in immediate power outages |
they may
damage circuit breakers |
|
A |
When testing
for blown fuses in a three-phase supply circuit to a motor, what would
be an acceptable method? |
apply a
voltage tester diagonally across the tops of the fuses and the bottoms
of the other fuses |
ensure the
circuit is de-energized, and then use an ohmmeter or continuity tester
connected across the bottoms of the fuses |
ensure the
circuit is de-energized, and then use an ohmmeter or continuity tester
connected across the tops of the fuses |
apply a
voltage tester across the tops of the fuses |
|
A |
In order to
definitively determine whether or not fuse "2", shown in the
illustration is blown using an on-line testing technique, across what
points would you connect the voltmeter leads? Illustration EL-0062 |
the bottom
of fuse "2" to the top of either fuse "1 or 3" |
the bottom
of fuse "2" to the bottom of either fuse "1 or 3" |
the top of
fuse "2" to the bottom of either fuse "1 or 3" |
the top of
fuse "2" to the top of either fuse "1 or 3" |
|
B |
To test
fuses in an energized circuit, what testing apparatus or meter should
be used? |
resistance
meter |
voltmeter |
megohmmeter |
continuity
tester |
|
A |
What would
cause a fuse to blow? |
the
electrical current exceeds the rated value of the fuse |
the flow of
current to the protection device is reversed |
an electric
motor is stopped suddenly by opening a switch |
unequal
resistors are connected in parallel |
|
D |
When
replacing a fuse with one of a ampere higher rating than the original,
which of the following is true? |
It reduces
the possibility of short circuits. |
It creates a
larger voltage drop in the circuit being protected. |
It increases
the efficiency of the equipment by allowing more current to be used. |
It endangers
the apparatus it is supposed to protect. |
|
A |
If a digital
multimeter is set up as shown in figure "A" of the illustration, what
would be displayed on the screen if the fuse being tested is not blown
and has proper continuity? Illustration EL-0210 |
0.001 ohms |
OL volts |
470 ohms |
OL ohms |
|
B |
In figure
"A" of the illustration, what is the position of the circuit breaker?
Illustration EL-0033 |
on |
off |
tripped |
not possible
to determine |
|
A |
What is the
resistance reading at "2" on the megger scale shown in figure "A" of
the illustration? Illustration EL-0044 |
40 megohms |
40,000 ohms |
400 ohms |
40 ohms |
|
D |
As shown in
the illustrated plots of uncorrected and temperature corrected
insulation resistance readings for a particular piece of equipment, at
what point in time should the equipment have been refurbished or
replaced? Illustration EL-0120 |
2006 |
2008 |
2010 |
no
refurbishment or replacement was necessary through 2011 |
|
C |
In the
lighting distribution circuit shown in the illustrated lighting panel
L110 of the illustration, if all circuit breakers are closed and due
to a problem with the relevant feeder circuit breaker, there is a loss
of power on the incoming phase A, which of the following statements is
true? Illustration EL-0013 |
All of the
accommodation lighting circuits on the 01 deck, starboard side would
lose power. |
All of the
receptacles in the laundry would lose power. |
Half of the
accommodation lighting circuits on the 01 deck, port side would lose
power. |
Half of the
passageway lighting circuits on the 01 deck would lose power. |
|
D |
When a
fluorescent lamp has reached the end of its useful life, it should be
replaced immediately. If not, what condition could the resultant
flashing cause? |
tripping of
the lamp's circuit breaker |
exploding of
the lamp, causing glass to fly in all directions |
short
circuiting of adjacent lighting circuits |
damaging the
lamps starter and ballast circuit |
|
A |
When a
fluorescent lamp fails to light and both ends of the tube are severely
darkened, what must usually be replaced? |
the
fluorescent lamp tube |
the ballast |
the circuit
breaker |
the starter |
|
A |
As shown in
the illustration of a vessels navigational lighting circuit, if port
running light "1" burns out, the trouble buzzer will sound and the
port running light trouble lamp will illuminate. Switching to port
running light "2" clears the alarm. If port running light "1" is
replaced with a light of a smaller wattage and the circuit is switched
back to port running light "1", which of the following is true?
Illustration EL-0058 |
There may be
insufficient current to energize the trouble relay coil and to open
the contacts to silence the alarm. |
The trouble
buzzer may not have sufficient voltage to provide sound. |
The trouble
relay coil will overheat. |
The new
lower wattage light at port running light "1" will immediately burn
out. |
|
B |
What is
indicated by gradual blackening at the ends of component "4" shown in
figures "B" and "C" of the illustration? Illustration EL-0081 |
The circuit
current is too high. |
The tube is
nearing the end of its useful life. |
The circuit
voltage is too high. |
The unit is
in danger of exploding. |
|
C |
During
start-up of the circuit shown in figure "B" of the illustration, it is
noted that the ends of component "4" alternately glow and become dark
without the tube illuminating. What is the most probable cause for
this condition? Illustration EL-0081 |
component
"5" contacts are opening and closing thus prohibiting sufficient
current flow |
component
"2" is loose and due to the ship's vibrations makes and breaks contact |
component
"3" is shorted and therefore unable to produce the high voltage
required to start the lamp |
the power
system's voltage is fluctuating in and out of the range necessary for
proper operation |
|
A |
As shown in
the wiring diagram of the semi-automatic navigation lighting panel
circuit, what would cause the buzzer to sound and for the indicator
light to illuminate in the line section for a particular navigation
running light? Illustration EL-0108 |
a burned out
navigation light in effected line section |
transfer
switch in the "off" position |
master
switch in the "off" position |
a blown 10
amp fuse in master section |
|
C |
In an
ungrounded distribution system, as compared to a normal indication,
what is the indication on a switchboard of a current carrying
conductor making an accidental electrical contact with a wiring metal
conduit? |
reading of
1.0 on the power factor meter |
lower
switchboard wattmeter reading than normal |
totally
darkened switchboard ground-detecting light |
higher
switchboard voltmeter reading than normal |
|
A |
If all of
the ground detection lamps burn with equal brilliance, whether the
test button is depressed or released, what does this indicate? |
no
ground-faults exist |
a
ground-fault exists in all phases |
a high
impedance ground-fault exists |
a dead
ground-fault exists |
|
D |
A
switchboard ammeter indicates a reading slightly above 'zero' when the
leads are disconnected. What is this caused by? |
capacitors
inside the meter storing charges |
a poor
ground for the meter case |
static
electricity in the air |
mechanical
misalignment of the meter pointer |
|
A |
In a
three-phase electrical system, three ground detecting lamps are
provided. One lamp goes dark and the others increase in brightness
when the "ground test" button is pushed. What is indicated? |
there is a
ground on the line with the dark lamp |
this is a
normal condition |
the dark
lamp must be replaced |
there are
grounds on the lines with the bright lamps |
|
D |
A
three-phase electrical system is equipped with ground detecting lamps.
If one of the lamps is dark, and remains dark when the test switch is
operated, what does this indicate? |
there is a
ground in the line with the dark lamp |
there are
grounds in two of the three phases |
the voltage
to the dark lamp is less than that of the system |
the dark
lamp must be replaced |
|
D |
An open
primary coil in a simple potential transformer will be indicated by
which of the listed conditions? |
Low
resistance value on the primary coil. |
An infinite
resistance value on the secondary coil. |
Overloaded
secondary coil. |
No voltage
on the output of the secondary coil. |
|
D |
What would
be the source current and transformer current as shown in figure "B"
of the illustration, with the secondary tap connected as shown, if the
supply voltage at the branch circuit breaker is 440 VAC and the unity
power factor load current draw is 50 amps? Illustration EL-0083 |
source
current is 37.5 amps, transformer current 92.5 amps. |
source
current is 12.5 amps, transformer current is 62.5 amps. |
source
current is 37.5 amps, transformer current is 12.5 amps. |
source
current is 12.5 amps, transformer current is 37.5 amps. |
|
D |
If the
illustrated device in figure "B" has a step-up ratio of 10 to 1 what
voltage would be measured at the secondary shortly after the primary
of the device is connected to 110 volts DC with a current of 12 amps?
Illustration EL-0055 |
1000 volts |
1100 volts |
110 volts |
0 volts |
|
A |
How are
fuses usually rated? |
volts, amps,
and interrupting capacity |
watts |
volts and
amps only |
amps only |
|
C |
Due to the
operating characteristics of the system, time lag fuses (or
dual-element fuses) are necessary for use in what types of circuits? |
emergency
lighting circuits |
main
lighting circuits |
motor
starting circuit |
general
alarm circuits |
|
B |
What is the
characteristic that is associated with an "instantaneous-trip"
single-element type fuse? |
opens a
circuit by using a time delay element with a magnetic trip |
opens as
soon as the load current exceeds its set point |
allows a
preset delay between over current and melting |
resets
itself when the over current is corrected |
|
A |
Fuses are
sometimes placed in series with a thermal trip-type circuit breaker.
What is the purpose of a fuse used in this arrangement? |
short-circuit protection |
short
duration surge protection |
time-delay
protection |
sustained
overload protection |
|
D |
Which pair
of safety disconnect switches shown in the illustration represents the
exterior and interior views of a double throw switch? Illustration
EL-0176 |
C and D |
A and C |
A and B |
B and D |
|
C |
A
thermal-magnetic circuit breaker for a 300 KW alternator is rated at
500 amperes at full continuous load. Which of the following conditions
will trip the breaker? |
Sustained
current draw of 450 amperes for 2 hours. |
Sustained
current draw of 500 amperes for 10 minutes. |
Instantaneous current draw of 5,000 amperes. |
Momentary
current draw of 1000 amperes for 3 seconds. |
|
A |
What is the
basic similarity between a circuit breaker and a fuse? |
after a
short or overload condition, both should open to de-energize the
circuit |
after a
short or overload condition, both must be reset to re-energize the
circuit |
after a
short or overload condition, both have to be replaced before the
circuit can be reenergized |
a circuit
breaker and a fuse have no similarities |
|
A |
The arc
resulting from the tripping of a circuit breaker is prevented from
damaging the contacts. How is this done? |
directing
the arc into an arc chute |
an inverse
timed thermal trip for short circuit currents |
instantaneous magnetic trip for overload currents |
designing
the contacts to open slowly |
|
B |
As shown in
the illustration, which of the following pieces of equipment is
supplied with a circuit breaker providing both overload and
short-circuit protection? Illustration EL-0165 |
Lube Oil
Service Pump No. 1 |
Sewage
Treatment Plant |
Cargo Oil
Transfer Pump No. 1 |
S.W. Cooling
Circ. Pump No. 1 |
|
B |
Which of the
following pictures shown in the illustration is a control transformer,
usually used to step down line voltage for supplying reduced voltage
control circuits? Illustration EL-0177 |
A |
B |
C |
D |
|
A |
Which of the
following statements is true concerning step-down transformer
operation? |
The voltage
supplied to the primary side is greater than the voltage produced by
the secondary side. |
The current
drawn by the primary side is greater than the current delivered from
the secondary side. |
The kVA
consumed by the primary side is greater than the kVA produced by the
secondary side. |
The voltage
supplied to the primary side is lower than the voltage produced by the
secondary side. |
|
A |
Relative to
the number of turns of a secondary winding of a step-up transformer,
what will be the number of turns of a primary winding? |
the primary
winding will have fewer turns than the secondary winding |
the primary
winding will have the same number of turns but smaller wires than the
secondary winding |
the primary
winding will have twice as many turns as the secondary winding |
the primary
winding will have more turns than the secondary winding |
|
D |
When a
transformer is used to step down voltage, what statement is true? |
The low
voltage winding is part of the core. |
The low
voltage winding is not insulated. |
The low
voltage winding is the primary coil. |
The low
voltage winding is the secondary coil. |
|
A |
What is the
primary purpose associated with the use of transformers onboard ships
with AC generators? |
provide
different voltage values to operate various types of electrical
equipment. |
decrease
power output to modulating frequency controllers |
change line
frequency value |
increase
power output to modulating frequency controllers |
|
C |
An
autotransformer is equipped with a 50% tap, a 65% tap, and an 80% tap.
Which of the following statements is true concerning a load connected
to the 50% tap? |
The load is
receiving two times line voltage and drawing one half of line current. |
The load is
receiving one half of line voltage and drawing one half of line
current. |
The load is
receiving one half of line voltage and drawing two times line current. |
The load is
receiving two times line voltage and drawing two times line current. |
|
B |
If the
primary winding of a voltage transformer is connected to a steady DC
source, self-inductance and mutual inductance is not possible. As a
result, what part of the transformer will result in current overload? |
secondary
coil |
primary coil |
core |
contacts |
|
B |
What is the
purpose of a potential transformer in an electric circuit? |
generate its
own electrical power |
increase or
decrease circuit voltage as required |
convert AC
current to DC current |
transform
electrical energy into mechanical energy |
|
B |
The
transformer diagram shown in figure "B" of the illustration represents
what type of transformer? Illustration EL-0082 |
open delta
transformer |
step down
transformer with dual voltage secondary |
Scott-connected transformer |
autotransformer |
|
B |
Which of the
listed figures shown in the illustration represents a three phase
transformer connected in a wye-wye configuration? Illustration EL-0084 |
1 |
2 |
3 |
4 |
|
D |
If the
illustrated device in figure "B" has a step-up ratio of 10 to 1 what
voltage would be measured at the secondary shortly after the primary
of the device is connected to 110 volts DC and the primary current
stabilized with a current of 12 amps? Illustration EL-0055 |
1000 volts |
1100 volts |
110 volts |
0 volts |
|
D |
Besides the
fluorescent lamp itself and possibly a starter, which of the following
components is included in a fluorescent lighting fixture? |
Magnetic
resonator |
Magnetron |
Laser |
Ballast
(choke coil) |
|
B |
What is the
purpose of the inner phosphor coating of the fluorescent tube as shown
in figure "A" of the illustration? Illustration EL-0081 |
absorb
visible ultraviolet light and emit invisible white light |
absorb
invisible ultraviolet light and emit visible white light |
absorb
invisible ultraviolet light and emit invisible white light |
absorb
visible ultraviolet light and emit visible white light |
|
A |
Incandescent
lamps are classified according to the shape of the bulb and the type
of service, as well as the size and style of the base. How are
incandescent lamps rated? |
operating
voltage and wattage |
operating
resistance |
operating
frequency and impedance |
operating
reactance |
|
A |
Which of the
following figures shown in the illustration represents incandescent
lighting? Illustration EL-0122 |
A |
B |
C |
D |
|
D |
How is
electrical conductor insulation classed? Example: insulation class H |
conductor
current carrying capacity |
conductor
ampacity |
voltage
rating of the insulation |
limiting
internal hot spot temperature |
|
A |
Which of the
following materials is a good electrical insulator? |
wood |
silver |
gold |
copper |
|
D |
Which of the
following is the only known perfect dielectric for the purpose of
serving as electrical insulation? |
mica |
ceramic |
glass |
vacuum |
|
B |
What is "the
voltage per millimeter of insulation thickness that the insulation can
withstand without breaking down" called? |
Tensile
strength |
Dielectric
strength |
Mechanical
strength |
Shear
strength |
|
B |
What happens
to the life expectancy of insulation for each 10°C rise in operating
temperature? |
The life
expectancy is unaffected. |
The life
expectancy is halved. |
The life
expectancy is doubled. |
The life
expectancy is unpredictable. |
|
C |
Why are
large cable sizes often formed as individual conductors comprised of
several smaller strands? |
reduce the
overall weight of the wire run |
reduce the
number of supports needed for a horizontal overhead run |
obtain the
flexibility required for easy handling and reduces skin effect losses |
reduce the
resistance to current flow for a given wire size |
|
B |
When
electrical cables penetrate watertight bulkheads, what must be
provided for? |
cables
should be grounded on either side of the bulkhead |
a watertight
stuffing tube capable of accepting packing should be employed |
cables must
be bent to a radius of six diameters |
cables
should be secured by a clamp |
|
B |
Why is
copper often used as an electrical conductor? |
holds
insulation together well |
is able to
pass current with little opposition |
has high
resistance at low temperatures |
has a highly
polished surface |
|
A |
How are the
line losses in a distribution circuit kept to a minimum? |
using higher
voltage and lower current |
using higher
current and lower voltage |
increasing
the number of thermal relays in the circuit |
adding
rubber insulation conductors to the circuit |
|
A |
In the
diagram of the switchboard shown in the illustration, if one of the
turbines should fail due to a throttle trip, what will happen?
Illustration EL-0003 |
device
labeled 'BKR' for that alternator should automatically open because of
the reverse power relay |
emergency
generator should automatically start and be placed on line to supply
emergency load centers |
device
labeled 'EXC' will drive the alternator |
operator
must open all the devices labeled 'BKRS' to reduce the load on the
remaining turbo-alternator |
|
D |
In the
diagram of the switchboard shown in the illustration, what is the
purpose of the current transformers? Illustration EL-0003 |
transform
relatively high generator load current to low instrument input current
for voltmeters |
transform
relatively low generator load current to high instrument input current
for ammeters, wattmeters, and the power factor meter |
transform
relatively low generator load current to high instrument input current
for voltmeters |
transform
relatively high generator load current to low instrument input current
for ammeters, wattmeters, and the power factor meter |
|
D |
In the
diagram of the switchboard shown in the illustration, what is the
function of the device labeled "Gen. Bkr. Sw."? Illustration EL-0003 |
it allows
the alternator circuit breaker overload inverse time trip rating to be
remotely adjusted at the synchronizing panel |
it allows
the alternator circuit breaker trip function to be over-ridden |
it allows
the alternator circuit breaker short circuit trip rating to be
remotely adjusted at the synchronizing panel |
it allows
the alternator circuit breaker to be opened or closed remotely at the
synchronizing panel |
|
A |
What
application would the switchboard instrumentation panel shown in the
illustration best be suited for? Illustration EL-0040 |
main AC
generator |
main DC
generator |
electric arc
welder controller |
variable
frequency MG set |
|
A |
The timer
element of a reverse power relay cannot be energized unless what
condition is met? |
the power
flow is the same as the tripping direction |
the movement
of the disk is damped by a permanent magnet |
the power
flow is the opposite to the tripping direction |
one
generator is fully motorized |
|
C |
Which of the
following represents a characteristic of an ungrounded electrical
distribution system? |
Accidental
contact between one line and ground will always cause an outage. |
Double
ground faults on different phases will not cause an outage. |
Accidental
contact between one line and ground does not cause an outage. |
Ground
detection systems are unnecessary. |
|
D |
How is a
wattmeter electrically connected in a circuit? |
In parallel |
In series |
Inductively |
In
series-parallel |
|
B |
What is the
name of the part of the shipboard electrical system used to control
the distribution of power to the branch circuits? |
disconnect
links |
main
switchboard |
governor
relay box |
bridge
control panel |
|
C |
What is a
purpose of the automatic bus transfer device shown in the
illustration? Illustration EL-0014 |
Provide
power to the 450 VAC main bus from the 450 VAC emergency bus in the
emergency mode. |
Provide
power to the 450 VAC emergency bus from the 450 VAC main bus in the
emergency mode. |
Provide
power to the 450 VAC emergency bus from the emergency generator in the
emergency mode. |
Provide
power to the 450 VAC main bus from the emergency generator in the
emergency mode. |
|
D |
Upon failure
of the normal power supply, how is the emergency generator placed on
the line to feed power to the emergency bus? |
line
connection feeder |
power
failure alarm bus |
main bus tie
feeder |
automatic
bus transfer device |
|
B |
In the
illustration of the one line distribution system diagram, if the
ship's service generator on line fails, what statement is true
concerning the operation of the emergency diesel generator?
Illustration EL-0014 |
It will
automatically start and automatically supply power to the 450 VAC
section of the main bus through the automatic bus transfer device. |
It will
automatically start and automatically supply power to the 450 VAC
section of the emergency bus through the automatic bus transfer
device. |
It will
automatically start but the automatic bus transfer device must be
manually shifted to 'Emergency Power' to supply the 450 VAC section of
the emergency bus. |
It must be
manually started but once running will automatically supply power to
the 450 VAC section of the emergency bus through the automatic bus
transfer device. |
|
D |
Referring to
the containership one-line distribution diagram shown in the
illustration, what is the purpose of the transformers providing power
to the refrigerated container feeder bus? Illustration EL-0014 |
Prevent any
unintentional grounds in the main distribution system from affecting
the refrigerated container distribution system. |
Step up the
voltage from the main bus to the voltage required for the refrigerated
container feeder bus. |
Step down
the voltage from the main bus to the voltage required for the
refrigerated container feeder bus. |
Prevent any
unintentional grounds in the refrigerated container distribution
system from affecting the main distribution system. |
|
C |
Referring to
the containership one-line distribution diagram shown in the
illustration, what is the purpose of the feedback circuit breaker as
used to bypass the automatic bus transfer device? Illustration EL-0014 |
Since it is
normally closed, it is the means by which the emergency generator
control circuit senses the voltage at the main bus. |
Since it is
normally closed, it is the means by which the emergency generator
control circuit senses the voltage at the emergency bus. |
It allows
the emergency generator to feed the main bus during dead ship start
up, otherwise it is generally open and not used. |
It allows
the emergency generator to be paralleled with the ship's service
generators when additional power is needed. |
|
C |
Referring to
the containership one-line distribution diagram shown in the
illustration, what statement is true concerning the battery charger?
Illustration EL-0014 |
The battery
charger gets its AC power from the 120 VAC section of the main
switchboard and is capable of providing DC charging current to both
battery banks simultaneously. |
The battery
charger gets its AC power from the 120 VAC section of the emergency
switchboard and is capable of providing DC charging current to both
battery banks simultaneously. |
The battery
charger gets its AC power from the 120 VAC section of the emergency
switchboard and is capable of providing DC charging current to only
one battery bank at a given time. |
The battery
charger gets its AC power from the 120 VAC section of the main
switchboard and is capable of providing DC charging current to only
one battery bank at a given time. |
|
D |
How are
fuses usually rated? |
volts and
amps only |
watts |
amps only |
volts, amps,
and interrupting capacity |
|
C |
Due to the
operating characteristics of the system, time lag fuses (or
dual-element fuses) are necessary for use in what types of circuits? |
main
lighting circuits |
general
alarm circuits |
motor
starting circuit |
emergency
lighting circuits |
|
C |
What is the
characteristic that is associated with an "instantaneous-trip"
single-element type fuse? |
resets
itself when the over current is corrected |
opens a
circuit by using a time delay element with a magnetic trip |
opens as
soon as the load current exceeds its set point |
allows a
preset delay between over current and melting |
|
A |
Fuses are
sometimes placed in series with a thermal trip-type circuit breaker.
What is the purpose of a fuse used in this arrangement? |
short-circuit protection |
short
duration surge protection |
sustained
overload protection |
time-delay
protection |
|
A |
In a dual
element time-delay cartridge-type fuse, what type of protection is
provided for motor applications? |
short-circuit protection using a fusible link AND sustained overload
protection using a spring loaded soldered joint |
short-circuit protection using a spring loaded soldered joint AND
sustained overload protection using a fusible link |
sustained
overload protection using a spring loaded soldered joint only |
short-circuit protection using a fusible link only |
|
A |
A fuse is
the most common type of protection against a short-circuit fault in LV
distribution circuits, motor circuits and for portable appliances.
What is a major drawback or deficiency with the use of fuse? |
It is
insensitive to small over current. |
It has a
very slow speed of operation at high short circuit fault current. |
It generates
a lot of heat when activated. |
It does not
provide protection in case of a short circuit. |
|
D |
By what
means does a molded-case breaker provide protection against short
circuits? |
use of a
shading coil |
use of a
thermal trip unit |
use of an
arc quencher |
use of a
magnetic trip unit |
|
C |
As shown in
figures "E" and "F" of the pictured high voltage rack mounted circuit
breaker, which figure represents the circuit breaker position when in
the open or tripped position? Illustration EL-0167 |
A |
B |
C |
D |
|
D |
When the
operating handle of a molded-case circuit breaker is in the
mid-position, what does this indicate? |
the circuit
breaker is switched off |
the circuit
breaker is switched on |
the circuit
breaker has been reset |
the circuit
breaker has tripped |
|
D |
As shown in
the illustration, which of the following pieces of equipment is
supplied with a circuit breaker providing both overload and
short-circuit protection? Illustration EL-0165 |
Cargo Oil
Transfer Pump No. 1 |
Lube Oil
Service Pump No. 1 |
S.W. Cooling
Circ. Pump No. 1 |
Sewage
Treatment Plant |
|
C |
What is a
bus disconnect link used to isolate? |
positive and
negative buses from the neutral |
one bus bar
from the ground detection system |
the
generator circuit breaker from the bus |
different
bus phases from the equalizer connection |
|
D |
What is
meant by the term 'dielectric'? |
good
conductor |
current flow |
semiconductor material |
electrical
insulator |
|
C |
What is the
greatest single cause of electrical failures? |
high
inductance |
too frequent
testing |
the
breakdown of insulation |
over current |
|
C |
What is a
common type of protective covering used on electrical conductors? |
silver
sheathing |
Babbitt
sheathing |
rubber or
plastic |
plain paper |
|
A |
Which of the
listed types of lighting fixtures does the diagram shown in figure "A"
of the illustration represent? Illustration EL-0081 |
Low pressure
mercury fluorescent |
High
pressure mercury fluorescent |
Low voltage
quartz |
High
pressure sodium |
|
D |
What type of
circuit is represented by the diagram shown in the illustration?
Illustration EL-0058 |
dual speed,
2-winding motor controller circuit |
common
fluorescent lighting circuit |
uninterruptible power supply circuit |
navigation
running light circuit |
|
D |
As shown in
the illustration, the change-over switch is what type of device?
Illustration EL-0058 |
single-pole,
single-throw switch |
double-pole,
single-throw switch |
single-pole,
double-throw switch |
double-pole,
double-throw switch |
|
A |
As shown in
the illustration, what event would give the same indication that would
occur when a stern light circuit fuse blows open? Illustration EL-0058 |
stern light
"2" burns out |
trouble
buzzer coil open circuits |
trouble
relay normally closed contacts open |
stern light
trouble lamp burns out |
|
D |
What is the
purpose of the capacitor within component "5" of the circuit shown in
figure "B" of the illustration? Illustration EL-0081 |
counteract
the inductive reactance in the circuit |
discharge
the neon within the envelope |
store power
to operate the circuit should "D" open |
prolong the
life of the component's contacts |
|
D |
As shown in
the illustration, which of the lighting fixtures represents an
incandescent bulb? Illustration EL-0122 |
D |
C |
A |
B |
|
B |
What are the
operating characteristics of a step-down potential transformer in
terms of the secondary load? |
reduced
voltage and reduced current |
reduced
voltage and increased current |
reduced
power (kVA) |
reduced
current and increased voltage |
|
D |
Which of the
listed transformers uses a single winding to produce voltage
transformation? |
Isolation
transformers |
Step-up
transformers |
Step-down
transformers |
Autotransformers |
|
B |
What is the
function of the autotransformers used with autotransformer starters
used on some large AC motors? |
provide
increased torque for starting |
provide
reduced voltage for starting |
provide
speed control |
provide
increased voltage for starting |
|
C |
How are
power transformers rated? |
kilowatt-volts |
kilowatts-amps |
kilovolt
amperes |
ampere-turns |
|
B |
Why are
transformer cores laminated? |
to reduce
secondary flux |
to reduce
eddy currents |
to reduce
flux leakage flux |
to reduce
hysteresis |
|
B |
What is the
purpose of the device labeled 'Man-Auto Sw.' in the illustrated
switchboard? Illustration EL-0003 |
enable the
operator to read the field voltage on device 'REG ADJ' or device 'MAN
ADJ' |
shift from
the automatic voltage regulator to manual voltage control or vice
versa |
shift the
governor control from manual to automatic/zero droop or vice versa |
supply
regulated control power to the switchboard |
|
A |
Which of the
listed sections of an emergency switchboard is used to supply power
for alarm signals under emergency conditions? |
The 24 volt
DC bus |
The 120
volt, 60 cycle, 3 phase bus |
The
generator and bus transfer section |
The 450
volt, 60 cycle, 3 phase bus |
|
D |
The timer
element of a reverse power relay cannot be energized unless what
condition is met? |
one
generator is fully motorized |
the power
flow is the opposite to the tripping direction |
the movement
of the disk is damped by a permanent magnet |
the power
flow is the same as the tripping direction |
|
D |
When
electrical cables penetrate watertight bulkheads, what must be
provided for? |
cables
should be secured by a clamp |
cables
should be grounded on either side of the bulkhead |
cables must
be bent to a radius of six diameters |
a watertight
stuffing tube capable of accepting packing should be employed |
|
D |
What is the
reason that some electric cables are formed of stranded wire? |
stranded
wire assures good conductivity at junction points |
stranded
wire decreases the weight for a given size wire |
stranded
wire increases the current carrying capability for a given size wire |
stranded
wire increases their flexibility over solid wire and reduces skin
effect losses |
|
C |
Which of the
following characteristics is most critical in determining the wire
gauge size of the cable to be used in a particular circuit? |
inductance
per unit length |
weight per
unit length |
current
rating |
voltage
rating |
|
B |
As shown in
the illustration, which of the following pieces of equipment is fed
with the three conductor cable with the individual conductors having
the smallest cross-sectional area? Illustration EL-0165 |
S.W. Cooling
Circ. Pump No. 1 |
Sewage
Treatment Plant |
Cargo Oil
Transfer Pump No. 1 |
Lube Oil
Service Pump No. 1 |
|
D |
How are the
line losses in a distribution circuit kept to a minimum? |
adding
rubber insulation conductors to the circuit |
increasing
the number of thermal relays in the circuit |
using higher
current and lower voltage |
using higher
voltage and lower current |
|
C |
Why is it
necessary to perform periodic testing of correctly rated and properly
installed circuit breakers? |
to insure
they will be able to withstand at least 125% of applied voltage |
to insure
they can trip faster as they increases in age |
to insure
they will continue to provide the original degree of protection |
to insure
they do not exceed their interrupting capacity |
|
A |
What should
be done when performing maintenance of circuit breaker contacts? |
inspect for
wear and misalignment of main contacts |
use a
metallic oxide abrasive cloth to dress contacts |
smooth
roughened contact surfaces with a file |
apply a thin
film of oil on contact surfaces |
|
D |
Which of the
listed classes of electrical insulation is suited for the highest
operating temperature? |
Class 90 (O) |
Class 130 |
Class 105 |
Class 180
(H) |
|
B |
Which of the
following procedures should be used to maintain a large electric motor
during periods of inactivity? |
A thin layer
of air-drying varnish should be applied on the windings. |
Space
heaters should be used to prevent condensation of moisture. |
Spraying a
solvent periodically to remove carbon dust. |
Compressed
air should be blown over areas where dust is deposited. |
|
B |
To check the
three line fuses protecting a three-phase motor using a multimeter set
up as a voltmeter, what should be done FIRST? |
place the
leads across the 'hot' ends of the fuses |
place the
starter in the 'stop' position |
make sure
the motor is operating at full load to guard against a false reading |
place the
leads across the bottom ends of the fuses |
|
C |
As a general
rule, what is the first troubleshooting action to be taken in checking
inoperative electric circuits? |
draw a one
line diagram of the circuitry |
take megger
readings |
test all
fuses and measure the line voltage |
insulate the
apparatus from ground |
|
D |
In order to
definitively determine whether or not fuse "1", shown in the
illustration is blown using an on-line testing technique, across what
points would you connect the voltmeter leads? Illustration EL-0062 |
the top of
fuse "1" and the top of either fuse "2 or 3" |
the bottom
of fuse "1" and the bottom of either fuse "2 or 3" |
the top of
fuse "1" and the bottom of either fuse "2 or 3" |
the bottom
of fuse "1" and the top of either fuse "2 or 3" |
|
A |
To test
fuses in an energized circuit, what testing apparatus or meter should
be used? |
voltmeter |
continuity
tester |
megohmmeter |
resistance
meter |
|
D |
In addition
to short circuits and sustained overloads, in what other situation are
fuses likely to blow? |
low fuse
holder clip to fuse contact resistance |
oversized
fuses in terms of amp rating |
low ambient
temperatures |
loose fuse
holder clips |
|
B |
When
replacing a fuse with one of a ampere higher rating than the original,
which of the following is true? |
It reduces
the possibility of short circuits. |
It endangers
the apparatus it is supposed to protect. |
It creates a
larger voltage drop in the circuit being protected. |
It increases
the efficiency of the equipment by allowing more current to be used. |
|
D |
If a digital
multimeter is set up as shown in figure "A" of the illustration, what
would be displayed on the screen if the fuse being tested is blown?
Illustration EL-0210 |
OL volts |
470 ohms |
0.001 ohms |
OL ohms |
|
C |
If a circuit
breaker that utilizes built-in, current limiting fuses (CLF's), cannot
be closed or reset, what may be the problem? I. A blown current
limiting fuse due to a short-circuit condition II. A missing current
limiting fuse |
I only |
II only |
Either I or
II |
Neither I
nor II |
|
D |
The ground
indicating light on the main electrical switchboard is indicating a
ground. What is the best procedure for locating the grounded circuit? |
check
circuit resistances with a megohmmeter connected between the grounded
line and the distribution panel framework |
check all
circuits for continuity |
trace the
circuit paths while looking for burned spots |
open the
circuit breakers on the distribution panel, one at a time, until the
lights no longer indicate a ground |
|
C |
Before any
work on electrical or electronic equipment is performed, which of the
following precautions should be carried out? |
Station a
man at the circuit supply switch. |
Bypass the
interlocks. |
Secure and
tag the supply circuit breaker in the open position. |
De-energize
the applicable switchboard bus. |
|
D |
In the
illustration what is the component labeled "C"? Illustration EL-0033 |
trip bar |
connection
terminal |
moving
contact |
fixed
contact |
|
D |
Two AC
generators of the same capacity are operating in parallel. One with a
zero speed droop setting and the other with a 5% speed droop. If its
capacity is not exceeded, what will be the characteristic of the unit
whose governor has the zero speed droop setting? |
it will have
poor sensitivity characteristics |
it will have
poor power response |
it will
assume the smaller share of the load |
it will
maintain the frequency of the system |
|
A |
What are the
operational characteristics of the two alternators with the
speed-droop curves shown in figure "A" of the illustration?
Illustration EL-0025 |
machine "A"
is a droop machine, while machine"B" is an isochronous machine |
machine "A"
and machine "B" are both isochronous machines |
machine "A"
and machine "B" are both droop machines |
machine "A"
is an isochronous machine, while machine "B" is a droop machine |
|
B |
In
preparation for paralleling generators, if the electric plant
condition is as shown by graph "A", what would be the rotational
status of the synchronizing lamps as shown in circuit "B"?
Illustration EL-0002 |
Revolve
slowly in the slow direction. |
Revolve
slowly in the fast direction. |
Revolve
rapidly in the slow direction. |
Remain
stationary. |
|
C |
From the
illustration shown in figure "C", what can be determined from the
speed droop characteristics of generator A and generator B?
Illustration EL-0025 |
Generator A
has a greater speed droop value than generator B and generator A will
take a greater share of the load than generator B. |
Generator A
has a greater speed droop value than generator B and generator B will
take a greater share of the load than generator A. |
Generator A
has a lower speed droop value than generator B and generator A will
take a greater share of the load than generator B. |
Generator A
has a lower speed droop value than generator B and generator B will
take a greater share of the load than generator A |
|
C |
Assuming the
alternator shown in figure "A" of the illustration is equipped with a
diode plate as configured in figure "D", what is the purpose of the
diode plate? Illustration EL-0037 |
It inverts
exciter armature DC to AC for rotating main field excitation, but does
not eliminate the need for brushes. . |
It rectifies
exciter armature AC to DC for rotating main field excitation, but does
not eliminate the need for brushes.. |
It rectifies
exciter armature AC to DC for rotating main field excitation and
eliminates the need for brushes. |
It inverts
exciter armature DC to AC for rotating main field excitation and
eliminates the need for brushes. |
|
D |
As shown in
figure "B" of the illustration, what is the purpose of the synchronous
compensator? Illustration EL-0133 |
provide
additional reactive power to the mains beyond the capability of the
frequency converter |
provide
additional active power to the mains beyond the capability of the
frequency converter |
provide
active power to the mains as the frequency converter has the ability
to provide only reactive power |
provide
reactive power to the mains as the frequency converter has the ability
to provide only active power |
|
A |
As Chief
Engineer, to prevent the motorization of an alternator what safety
device would you have checked quarterly? |
The reverse
power relay. |
The high
load alarm point for the alternator. |
The over
current relay. |
The high
frequency alarm for the alternator. |
|
B |
As shown in
the illustrated alternator protection scheme diagram, what device
provides the input to the overcurrent inverse time relay "OCIT", the
overcurrent instantaneous trip "OC (inst.)", and the negative phase
sequence relay "NPS"? Illustration EL-0067 |
potential
transformer |
current
transformer |
thermal
monitor sensors |
infrared
sensors |
|
A |
As shown in
the illustrated diagnostic setup for locating a shorted field coil of
a ten-pole salient pole alternator, if 240 VAC 60-Hz is applied across
the brushes, what would be the voltage drop across field coil #4 if
that field coil had shorted turns and the other field coils were free
of shorts? Illustration EL-0202 |
17 VAC |
25 VAC |
32 VAC |
24 VAC |
|
B |
What may be
the cause of an AC generator to fail to produce a voltage? |
short
circuit in the stator coils |
an open in
the rotor field circuit |
high mica
segments on the stator bus bar |
a tripped
bus circuit breaker |
|
D |
As shown in
the illustrated alternator protection scheme diagram, under what
circumstances would an earth leakage relay (EL) be used? Illustration
EL-0067 |
in grounded
low voltage systems |
in
ungrounded low voltage systems |
in high
voltage systems with a low impedance earthing resistor or transformer |
in high
voltage systems with a high impedance earthing resistor or transformer |
|
C |
As shown in
figure "A" of the illustration, what is the primary reason that the
propulsion transformers are configured differently so as to produce a
30 degree phase shift in the pulses between the two synchroconverters
supplying separate stator windings? Illustration EL-0160 |
to maximize
motor power output |
to maximize
motor power factor |
to minimize
motor shaft vibration |
to minimize
AC sine wave distortion |
|
D |
Power
conversion for use in DC propulsion drive motors is accomplished by
what type of converter? |
cycloconverters |
load
commutated converters |
pulse width
modulated converters |
silicon
controlled rectifier converters |
|
C |
The
conversion of constant frequency power into adjustable frequency power
in a modern AC propulsion drive system is commonly achieved through
the use of what electronic system components? |
transformers
and resistors |
potentiometers and diodes |
rectifiers
and thyristors |
rheostats
and resistors |
|
D |
A shown in
figure "A" of the illustrated propulsion motor variable speed drive,
what statement is true? Illustration EL-0140 |
both the
bridge rectifier and the controller inverter bridge are transistor
controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
thyristor controlled in terms of switching |
both the
bridge rectifier and the controller inverter bridge are thyristor
controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
transistor controlled in terms of switching |
|
C |
What type of
electric propulsion system converter is shown in the illustration?
Illustration EL-0155 |
pulse width
modulation converter |
cycloconverter |
synchroconverter |
controlled
rectifier converter |
|
A |
As shown the
illustration of a cycloconverter for an AC synchronous propulsion
motor, what statement is true concerning the operating motor
frequency? Illustration EL-0157 |
The
operating motor frequency is generally limited to less than one-third
of mains line frequency. |
The
operating motor frequency is generally limited to three times the
mains line frequency. |
The
operating motor frequency is generally not limited regardless of the
mains line frequency. |
The
operating motor frequency is generally limited to that equal to the
mains line frequency. |
|
C |
Which of the
following statements is true concerning a large polyphase synchronous
main propulsion motor as used in an electric propulsion drive system? |
Resistance
is gradually added to the rotor circuit. |
The starting
current is held below the rated current. |
The motor is
started as an induction motor. |
The field
winding is energized for starting purposes only. |
|
C |
Which of the
following is a disadvantage of electric drive propulsion systems? |
Main
propulsion power may also be directed to ships electrical service
distribution. |
The
propeller speed and direction of rotation are easily controllable. |
Propulsion
motors are required along with electrical power generation machinery. |
Location of
electric power generation machinery is flexible. |
|
B |
What
statement is TRUE concerning the Azipod propulsion system?
|
It is an
electric drive system in which the motor drives a controllable pitch
propeller (CPP). |
It is an
electric drive system where the propulsion motor is installed in a
submerged housing capable of swiveling. |
It is an
electric drive system that incorporates a DC motor. |
It is an
electric drive system using water jets. |
|
A |
Which of the
following statement is TRUE concerning Azipod propulsion systems? |
The system
integrates propulsion and steering into one function. |
The system
requires the use of a controllable pitch propeller. |
The system
requires the need for a separate rudder. |
The pod
assembly swivels on a horizontal axis. |
|
D |
As shown in
figure "B" of the illustration, what statement is true concerning
"regenerating" operation? Illustration EL-0162 |
by applying
torque in the same direction of rotation direction, the motor briefly
regenerates power back into the mains, which rapidly slows down the
motor |
by applying
torque in the same direction of rotation direction, the motor briefly
regenerates power back into the mains, which rapidly speeds up the
motor |
by applying
torque in the opposite direction of rotation direction, the motor
briefly regenerates power back into the mains, which rapidly speeds up
the motor |
by applying
torque in the opposite direction of rotation direction, the motor
briefly regenerates power back into the mains, which rapidly slows
down the motor |
|
C |
How is the
main shaft rotation on an AC diesel-electric propulsion vessel
normally reversed? |
reversing
the prime mover rotation |
increasing
the generator frequency |
reversing
any two phase leads to the motor |
decreasing
the generator frequency |
|
D |
How is the
speed of the propeller shaft directly coupled to an AC synchronous
propulsion motor changed when powered by a variable frequency
alternator in an AC turboelectric drive system? |
varying the
field strength of the motor |
varying the
field strength of the generator |
varying the
number of motor poles |
varying the
turbine speed |
|
B |
How is the
direction of propeller shaft rotation changed when directly coupled to
an AC synchronous motor when driven by a variable frequency alternator
in an AC turbo-electric drive system? |
Reversing
the polarity of the propulsion motor |
Reversing
the phase sequence of power to the motor |
Reversing
the polarity of the propulsion generator |
Reversing
the rotation of the steam turbine |
|
A |
What
statement is TRUE concerning the speed of a synchronous ac propulsion
motor? |
The speed is
directly proportional to the frequency applied to its stator windings. |
The speed is
directly proportional to the frequency applied to its rotor windings |
The speed is
inversely proportional to the frequency applied to its stator
windings. |
The speed is
inversely proportional to the frequency applied to its rotor windings. |
|
A |
By what
common means is the speed of an AC propulsion motor on a
diesel-electric propulsion ship controlled? |
by varying
the input frequency of the voltage to the motor |
by
decreasing the motor voltage |
by
increasing the current to the motor |
by
increasing the motor voltage |
|
D |
How is the
direction of rotation of the main propulsion motor in a modern AC
propulsion drive system reversed? |
changing the
direction of current flow in the motor's field winding |
power
directional relays |
reversing
the direction of current flow in the armature |
electronically changing the phase sequence of the voltages generated
by the power converter |
|
C |
A shown in
figure "A" of the illustrated propulsion motor variable speed drive,
what statement is true? Illustration EL-0140 |
both the
bridge rectifier and the controller inverter bridge are thyristor
controlled in terms of switching |
both the
bridge rectifier and the controller inverter bridge are transistor
controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
transistor controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
thyristor controlled in terms of switching |
|
C |
How is the
speed of the propeller shaft directly coupled to an AC synchronous
drive motor changed when powered by either a dedicated or integrated
constant frequency alternator in an AC diesel-electric drive system? |
Varying the
generator speed |
Varying the
number of motor poles |
Varying the
output frequency of the power converter |
Varying the
field strength of the generator |
|
B |
A common
method used to control the speed of a synchronous AC propulsion motor
on a diesel-electric propulsion drive is by what means? |
increasing
the current to the motor |
varying the
input frequency of the voltage to the motor |
decreasing
the motor voltage |
increasing
the motor voltage |
|
C |
As shown in
the illustrated electric propulsion control scheme for a twin screw
vessel, when the two shaft speeds are within 5% of each other, the
bridge may select "shaft synchro-phasing mode". What statement is true
regarding the purpose of this operating mode? Illustration EL-0168 |
Vibration
sensors are used to achieve identical shaft speeds and propeller
synchronization to minimize vibration. |
The
respective shaft speed sensors alone are used to achieve identical
shaft speeds without regard to propeller position to achieve even
power development. |
The
respective shaft speed and shaft position sensors are used to achieve
identical shaft speeds and propeller synchronization to minimize shaft
vibration. |
Cavitation
sensors are used to achieve identical shaft speeds and propeller
synchronization to minimize vibration. |
|
D |
Which of the
listed temperature measuring devices installed on a large
turbo-electric alternating current propulsion generator would be the
most reliable for monitoring generator temperatures to avoid premature
winding insulation failure? |
Current
transformers are the most reliable means of monitoring generator
temperatures |
Temperature
sensors measuring the temperature of the cooling air associated with
the generator air cooler |
Temperature sensors measuring the temperature of the cooling water
associated with the
generator
air cooler |
Temperature
sensors inserted in the stator slots for measuring stator winding
temperature. |
|
A |
Which of the
listed devices is most likely to be installed on a large modern
diesel-electric alternating current propulsion generator for
commercial ship propulsion for the purposes of fire suppression? |
A CO2 fire
extinguishing system. |
A Halon fire
extinguishing system. |
A dry
chemical fire extinguishing system. |
A foam fire
extinguishing system. |
|
C |
Propulsion
AC generators creating 4160 VAC use transformers to provide nominally
120 VAC to the automatic voltage regulator. What is the turns ratio of
this step-down transformer? |
1:4 |
4:1 |
35:1 |
40:1 |
|
B |
An electric
propulsion drive system in which the propulsion generator supplies
power to both the propulsion motor and ship service loads is referred
to as what type of system? |
a dedicated
system |
an
integrated system |
a composite
system |
a
multi-purpose system |
|
A |
An electric
propulsion drive system in which the propulsion generator only
supplies power to the propulsion motor is referred to as what type of
system? |
a dedicated
system |
a composite
system |
a
multi-purpose system |
an
integrated system |
|
A |
In addition
to improper brush pressure or seating, what can result in excessive
sparking at the brushes of a DC propulsion motor? |
improper
positioning of brush rigging outside the neutral plane |
reversed
main field polarity with respect to the armature |
operating at
continuously varying loads such as during maneuvering |
reversed
armature polarity with respect to the field |
|
D |
Which of the
listed temperature measuring devices installed on a large
turbo-electric alternating current propulsion generator would be the
most reliable for monitoring generator temperatures to avoid premature
winding insulation failure? |
Temperature
sensors measuring the temperature of the cooling air associated with
the generator air cooler |
Temperature
sensors measuring the temperature of the cooling water associated with
the generator air cooler |
Current
transformers are the most reliable means of monitoring generator
temperatures |
Temperature
sensors inserted in the stator slots for measuring stator winding
temperature. |
|
A |
While
standing an "at sea watch" onboard a modern rectified DC
diesel-electric drive ship you notice the transformer core temperature
slowly rising. What should be your FIRST action? |
check the
transformer ventilation fans for proper operation |
send the
oiler to look for fires in the transformer |
notify the
bridge that you need to slow down |
reduce load
by tripping lighting circuits |
|
B |
While
standing an "at sea watch" onboard an AC diesel-electric drive ship
with a synchronous propulsion motor, you notice that the kwatt load is
at roughly 75% of capacity with a leading power factor less than 1.
Ideally what would be the character of the power factor associated
with the main power distribution including all motors? |
zero |
unity |
lagging |
leading |
|
D |
On a vessel
with turbo-electric drive, which of the following conditions would
indicate that the propulsion motor had dropped out of synchronization
with the propulsion generator? |
Tripped main
motor interlocks |
Closed
contact in the field circuits |
Overheated
crosstie busses |
Excessive
vibration of the vessel |
|
B |
What
equipment for modern SCR rectified DC propulsion drive systems is
usually included in the package? |
propulsion
generators which produce DC power that is directly delivered to the
series wound DC propulsion motor |
propulsion
generators which produce AC power that is converted to DC power for
the shunt wound DC propulsion motor |
propulsion
generators which produce AC power that is directly delivered to the
synchronous AC propulsion motor |
propulsion
generators which produce DC power that is converted to AC power for
the propulsion motor |
|
B |
Power
conversion for use in DC propulsion drive motors is accomplished by
what type of converter? |
pulse width
modulated converters |
silicon
controlled rectifier converters |
load
commutated converters |
cycloconverters |
|
A |
As shown in
the illustration, if the port propulsion motor field excitation
circuit experienced a failure, what individual component failure would
allow the use of the standby excitation transformer and standby field
controller to resume normal operation? Illustration EL-0164 |
port field
controller |
port motor
field winding |
port
rotating rectifier |
port rotary
transformer |
|
B |
While
standing an "at sea watch" onboard a modern rectified DC
diesel-electric drive ship you notice the transformer core temperature
slowly rising. What should be your FIRST action? |
reduce load
by tripping lighting circuits |
check the
transformer ventilation fans for proper operation |
notify the
bridge that you need to slow down |
send the
oiler to look for fires in the transformer |
|
C |
While
underway onboard a DC diesel electric drive ship, you notice excessive
sparking of the brushes on the main propulsion motor. What should be
your FIRST action? |
decrease the
speed of the main generator |
decrease the
main generator voltage |
notify the
bridge that you will need to slow down to reduce the electrical load |
decrease the
motor field current |
|
C |
Upon failure
of the normal power supply, how is the emergency generator placed on
the line to feed power to the emergency bus? |
main bus tie
feeder |
power
failure alarm bus |
automatic
bus transfer device |
line
connection feeder |
|
C |
In the
illustrated one line diagram, if the ship's service generator on line
fails, what statement is true concerning the operation of the
emergency diesel generator? Illustration EL-0014 |
It will
automatically start and automatically supply power to the 450 VAC
section of the main bus through the automatic bus transfer device. |
It will
automatically start but the automatic bus transfer device must be
manually shifted to 'Emergency Power' to supply the 450 VAC section of
the emergency bus. |
It will
automatically start and automatically supply power to the 450 VAC
section of the emergency bus through the automatic bus transfer
device. |
It must be
manually started but once running will automatically supply power to
the 450 VAC section of the emergency bus through the automatic bus
transfer device. |
|
B |
As shown in
the illustrated one-line diagram of a two-tiered emergency power
system for a passenger ship, what statement is true? Illustration
EL-0166 |
On a loss of
normal ship's power, the final emergency loads power source is battery
(from AC/DC UPS "A"), whereas the temporary emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the temporary emergency loads power source is
battery (from AC/DC UPS "B"), whereas the final emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the final emergency loads power source is battery
(from AC/DC UPS "B"), whereas the temporary emergency loads power
source is the emergency generator. |
On a loss of
normal ship's power, the temporary emergency loads power source is
battery (from AC/DC UPS "A"), whereas the final emergency loads power
source is the emergency generator. |
|
D |
From the
information given in the illustration, which of the following
statements is correct? Illustration EL-0106 |
It is
possible for the main-emergency bus-tie circuit breaker and the
emergency generator circuit breaker to be simultaneously closed. |
The
emergency generator is capable of being connected directly to the main
480 VAC bus. |
Shore power,
in port, is only capable of feeding emergency loads. |
It is
normally the case where the main-emergency bus-tie circuit breaker and
any on-line ship's service generator circuit breakers be
simultaneously closed. |
|
A |
As shown in
the illustration of a DC diesel-electric propulsion drive system, what
would be the set-up contactor configurations if #1 M/E is to be
secured, so that only #2 M/E diesel-generator is set up to supply both
propulsion motors? Illustration EL-0141 |
contactors
G2 and S1 pulled in; contactors G1 and S2 dropped out |
contactors
G2 and S1 dropped out; contactors G1 and S2 pulled in |
contactors
G2 and S2 dropped out; contactors G1 and S1 pulled in |
contactors
G2 and S2 pulled in; contactors G1 and S1 dropped out |
|
D |
Before any
work on electrical or electronic equipment is performed, which of the
following precautions should be carried out? |
De-energize
the applicable switchboard bus. |
Station a
man at the circuit supply switch. |
Bypass the
interlocks. |
Secure and
tag the supply circuit breaker in the open position. |
|
D |
For the
purposes of safety and determining the shock hazard, nominal voltage
is defined as the normal electrical system design voltage. This can be
determined from what is displayed on nameplates, data plates,
schematics, or single-line diagrams. What does the nominal voltage
represent? |
phase to
hull ground voltage |
phase to
neutral voltage |
phase to
phase voltage |
average of
phase to phase and phase to hull ground voltages |
|
C |
What is the
minimum threshold voltage at which the skin offers no appreciable
resistance to electrical current flow and is known as the
"skin-puncture voltage"? |
208 VAC |
480 VAC |
600 VAC |
1000 VAC |
|
D |
Which
activity or event accounts for the most electrical accidents resulting
in injury? |
failures
during normal operation |
performing
electrical maintenance |
performing
electrical repair work |
conducting
electrical troubleshooting |
|
B |
Why should
an electrical worker determine the nominal voltage of a circuit first
before making contact with the circuit?
|
So the
worker can select the proper voltage tester to use before contact with
the circuit is made. |
So the
worker can select the proper PPE and voltage tester to use before
contact with the circuit is made. |
So the
worker can select the proper PPE to use before contact with the
circuit is made. |
As long as
the circuit is properly tagged/locked out, no determination of the
nominal voltage is necessary. |
|
C |
When taking
voltage measurements, for reasons of electrical safety, what should be
the proper sequence of actions? |
When taking
voltage measurements, the sequence of steps is not critical as long as
PPE is worn and a voltage tester is used. Voltage measurements can be
taken with confidence. |
First,
measure the actual voltage. Next, select the proper PPE and voltage
tester to use based on this measured voltage. Finally, take voltage
measurements with confidence. |
First,
determine the nominal voltage from the nameplate. Next, select the
proper PPE and voltage tester to use based on this nameplate voltage.
Finally, take voltage measurements with confidence. |
First,
measure the actual voltage. Next, select the proper voltage tester to
use based on this measured voltage. Finally, take voltage measurements
with confidence. |
|
B |
When
performing an absence-of-voltage test before commencing repair work,
at the minimum where must the absence-of-voltage test be performed? |
At the main
feeder circuit breaker |
At the point
of contact where the work will take place |
At the
load-side disconnect switch |
At the
source disconnect branch circuit breaker |
|
A |
When
performing an absence-of-voltage test, a live-dead-live test may be
required in conjunction with the absence-of-voltage test. What is the
purpose of the live-dead-live test? |
The
live-dead-live test proves the functional ability of the voltage
tester to measure voltage prior to and after conducting the
absence-of-voltage test which validates the results of the
absence-of-voltage test. |
The
live-dead-live test proves the functional ability of the voltage
tester to measure voltage after conducting the absence-of-voltage test
which validates the results of the absenceof-voltage test. |
The
live-dead-live test proves the functional ability of the voltage
tester to measure voltage prior to conducting the absence-of-voltage
test which validates the results of the absence-ofvoltage test. |
The
absence-of-voltage test proves the functional ability of the voltage
tester to measure voltage prior to and after conducting the
live-dead-live test which validates the results of the live-dead-live
test. |
|
D |
What
statement is true concerning temporary protective grounds used to
establish an equipotential zone for the purposes of eliminating the
electric shock hazard? |
A shock
hazard exists only when there is a difference in potential between
conductors. |
A shock
hazard exists only when there is a difference in potential between a
conductor and hull ground. |
A shock
hazard exists when there is no difference in potential between
conductors or a conductor and hull ground. |
A shock
hazard exists when there is a difference in potential between
conductors or a conductor and hull ground. |
|
B |
What is the
minimum threshold voltage which requires electrical workers to be
insulated from energized conductors or circuit parts by wearing the
appropriate PPE while working in open enclosures? |
24 V |
50 V |
120 V |
480 V |
|
B |
Which figure
shown in the illustration represents the schematic symbol shown in
figure "2"? Illustration EL-0034 |
figure "A" |
figure "B" o |
figure "C" o |
figure "D" |
|
B |
As shown in
the illustrated devices and symbols, which of the symbols shown in the
illustration represents a standard normally closed relay contact?
Illustration EL-0005 |
E |
F |
I |
K |
|
A |
As shown in
figure "6" of the illustration, what does the symbol represent as used
in electrical drawings? Illustration EL-0026 |
maintaining
type push button with a mechanical interlock |
normally
closed contact held open mechanically by an interlock |
maintaining
type push button with an electrical interlock |
limit switch
with one set of normally open contacts |
|
C |
Which of the
electronic schematic symbols represents the capacitor illustrated in
figure "1" of the illustration? Illustration EL-0015 |
D |
A |
B |
C |
|
D |
What is the
shape of the schematic symbol for an operational amplifier used in an
analog circuit? |
trapezoid |
circle |
square |
triangle |
|
C |
Which of the
following statements concerning figure "6" of the illustration is
true? Illustration EL-0026 |
The symbol
represents an overload relay. |
The symbol
represents a computer cable pin plug. |
The symbol
represents a switch using maintained contact with "either/or" logic. |
The symbol
represents a switch which functions with analog parameters. |
|
D |
In figure
"1" of the illustration, what type of circuit breaker trip element is
featured? Illustration EL-0033 |
ambient
compensated trip |
shunt trip |
magnetic
trip |
thermal trip |
|
C |
Which
electrical schematic symbol shown in the illustration represents a
normally closed thermostat? Illustration EL-0059 |
1 |
6 |
8 |
9 |
|
C |
Which of the
electrical schematic symbols shown in the illustration represents a
normally closed limit switch? Illustration EL-0059 |
6 |
10 |
11 |
14 |
|
B |
What
statement is true concerning the electrical diagrams for the motor
controller shown in the illustration? Illustration EL-0007 |
Figure "A"
is a pictorial drawing and figure "B" is a wiring diagram. |
Figure "A"
is a wiring diagram and figure "B" is a ladder or line diagram
(schematic). |
Figure "A"
is a ladder or line diagram (schematic) and figure "B" is a wiring
diagram. |
Figure "A"
is a one line diagram and figure "B" is a ladder or line diagram
(schematic). |
|
D |
What type of
electrical diagram for the autotransformer type motor controller is
shown in the illustration? Illustration EL-0012 |
The diagram
is a wiring diagram. |
The diagram
is a block diagram. |
The diagram
is a one line diagram. |
The diagram
is a ladder or line diagram (schematic). |
|
C |
What type of
electrical diagram for the electrical distribution system is shown in
the illustration? Illustration EL-0014 |
The diagram
is a block diagram. |
The diagram
is a ladder or line diagram (schematic). |
The diagram
is a one line diagram. |
The diagram
is a wiring diagram. |
|
A |
What type of
electrical diagram for the shunt wound DC motor is shown in the
illustration? Illustration EL-0052 |
The diagram
is a pictorial drawing. |
The diagram
is a wiring diagram. |
The diagram
is a block diagram. |
The diagram
is a one line diagram. |
|
D |
What type of
electrical diagram for the steering control systems is shown in the
illustration? Illustration EL-0192 |
The diagram
is a one line diagram. |
The diagram
is a pictorial drawing. |
The diagram
is a wiring diagram. |
The diagram
is a functional block diagram. |
|
D |
Which figure
represents the schematic symbol shown in figure "2"? Illustration
EL-0034 |
figure "A" |
figure "C" |
figure "D" |
figure "B" |
|
A |
As shown in
the illustrated devices and symbols, which of the symbols represents a
standard normally closed relay contact? Illustration EL-0005 |
F |
E |
I |
K |
|
D |
As shown in
figure "6" of the illustration, what does the symbol represent as used
in electrical drawings? Illustration EL-0026 |
limit switch
with one set of normally open contacts |
normally
closed contact held open mechanically by an interlock |
maintaining
type push button with an electrical interlock |
maintaining
type push button with a mechanical interlock |
|
D |
What does
the symbol labeled "OL" represent as shown in the power circuit on
lines T1 and T3 to the motor as shown in figure "A" of the
illustration? Illustration EL-0011 |
overload
relay normally closed contacts |
non-renewable fusible link |
overload
relay magnetic coil |
overload
relay thermal heater |
|
D |
In
electrical circuit schematics, a normally open pressure switch is
represented by which of the symbols shown in the illustration?
Illustration EL-0059 |
4 |
1 |
7 |
2 |
|
D |
In comparing
a semiconductor diode to a vacuum tube diode, what statement is true? |
The
semiconductor diode has longer life, no warm-up time, and is more
delicate than the vacuum tube diode. |
The
semiconductor diode has shorter life, no warm-up time, and is less
delicate than the vacuum tube diode. |
The
semiconductor diode has longer life, longer warm-up time and is less
delicate than the vacuum tube diode. |
The
semiconductor diode has longer life, no warm-up time, and is less
delicate than the vacuum tube diode. |
|
D |
In
electronic circuitry, what does the abbreviation 'PCB' commonly
represent? |
pulse coded
binary |
personal
computer bits |
poly-coated
braid |
printed
circuit board |
|
A |
To minimize
magnetic field interaction between electrical conductors in physical
proximity, what is the best practice? |
at right
angles and as far as practicable from each other |
parallel and
as close as possible to each other |
at right
angles and as close as possible to each other |
parallel to
and as far as practicable from each other |
|
A |
The
multiplier prefix 'giga' (G) such as used in "gigabytes" represents
what multiplication factor? |
billion (10
to the 9th power) |
million (10
to the 6th power) |
trillion (10
to the 12th power) |
thousand (10
to the 3rd power) |
|
B |
Which of the
wave shapes shown in the illustration is termed a ramp or sawtooth
wave? Illustration EL-0088 |
E |
C |
A |
B |
|
D |
Which line
in figure "B" shown in the illustration represents the trailing edge
of the wave? Illustration EL-0088 |
5 |
3 |
6 |
4 |
|
D |
Given the
circuit and individual AC and DC voltage waveforms shown in figure "A"
producing the composite voltage waveform shown in figure "B", what
would be the value of the average current passing through the load
resistor with a resistance of 1 ohm? Illustration EL-0075 |
30 amps |
40 amps |
10 amps |
20 amps |
|
A |
What is the
correct name for the device used in an electrical circuit to change
alternating current to direct current? |
rectifier |
shunt |
current
transformer |
condenser |
|
B |
Which of the
following statements represents an application of a silicon controlled
rectifier? |
Used in
photo cell sensor circuits for boiler burners. |
Provides DC
power for a main propulsion motor. |
Used as a
voltage reference diode. |
Used to
eliminate AC power supply hum. |
|
A |
Capacitors
are commonly used on DC power supply circuits for engine room
automation consoles. For what functional purpose are they primarily
used in this application? |
filter out
'ripple' from rectification |
decrease the
average value of the output voltage |
prevent
overloads |
act as a
permanent load |
|
D |
All of the
schematic diagrams shown in the illustration represent which of the
listed solid-state circuits? Illustration EL-0069 |
Full-wave
rectifier bridge |
Half-wave
rectifier |
Flip-flop
generator |
Full-wave
rectifier |
|
B |
What does
the drawing in the illustrated circuit represent? Illustration EL-0063 |
a six phase
half wave rectifier |
a three
phase full wave rectifier |
a single
phase full wave rectifier |
a three
phase half wave rectifier |
|
C |
In the
regulated DC power supply illustrated, what is the function of
section"B"? Illustration EL-0085 |
half wave
rectification |
quarter wave
rectification |
full wave
rectification |
short wave
rectification |
|
C |
Which
section of the circuit shown in the illustration smoothes out highest
degree of pulsations? Illustration EL-0085 |
A |
B |
C |
D |
|
C |
What is the
function of section "D" of the circuit shown in the illustration?
Illustration EL-0085 |
a voltage
transformer |
a rectifier |
a voltage
regulator |
a filter |
|
B |
What is the
direction of electron current through the load resistor in the circuit
shown in the illustration? Illustration EL-0085 |
Always from
point "TP5" to the grounded end. |
Always from
the grounded end to point "TP5". |
It depends
on the instantaneous polarity at"T1". |
It cannot be
determined without a directional ammeter. |
|
D |
What will
happen to a carbon resistor operating in electrical equipment that is
NOT properly cooled? |
it will
change its value inversely proportional to the amount of heat
generated and time in service |
its
reliability factor will increase |
it will
always operate at the same ohmic value |
its
reliability factor will decrease |
|
A |
How can the
nominal resistance value of a typical carbon resistor in a circuit
best be determined? |
by the band
markings on the resistor |
by the
resistance value written on the resistor |
by the
physical size of the resistor |
by the
single solid body color of the resistor |
|
D |
When a
solid-state component of an electronic circuit is mounted to a
metallic mass, what is the general purpose of that mass? |
prevent
mechanical damage to solid-state components |
dissipate
stray magnetic currents |
prevent
vibration damage to delicate components |
act as a
heat sink |
|
A |
Although
saturable reactors are extremely useful in some applications, why is
their gain low? |
core
hysteresis losses |
inductive
reactance in the control winding |
IR drop
throughout the load winding |
eddy current
losses |
|
A |
Basically, a
magnetic amplifier is a saturable-core reactor with the addition of
what additional feature? |
a rectifier
in the load circuit |
AC to the
bias winding |
eddy current
protectors |
variable
capacitance to all windings |
|
B |
What is the
name of the semiconductor that decreases in resistance with an
increase in temperature? |
resistor |
thermistor |
thermopile |
diode |
|
C |
Which of the
pictured solid-state semiconductor devices in the illustration is a
rectifier bridge? Illustration EL-0068 |
2 |
5 |
3 |
4 |
|
A |
The
characteristics of the device shown in figure "8" of the illustration
includes a stable voltage and low current while operating. Because of
this, it can be suitably used in what type of circuit? Illustration
EL-0065 |
switching
and timing circuits |
class A and
B amplifiers |
DC power
supplies |
SCR power
circuits |
|
B |
What is the
name of the component labeled Q1 as shown in section "D" of the
regulated DC power supply illustrated? Illustration EL-0085 |
triac |
NPN bipolar
junction transistor |
PNP bioplar
junction transistor |
silicon-controlled rectifier |
|
C |
A triac
thyristor functions as a control device and can be thought of to
function similarly as which of the following circuits? |
a diode in
series with a temperature sensitive capacitor |
a triode
tube with an extra heavy grid element |
a
bidirectional SCR with a common gate |
two NPN
transistors in parallel with a common base lead |
|
A |
Which of the
following statements represents the important factor that must be
considered when replacing a faulty diode in a generators excitation
field rectifier assembly? |
Be certain
that the replacement diode is installed with the same polarity as the
one removed. |
The
replacement diode must be dipped in varnish prior to installation to
protect against humidity. |
Never alter
the diode alignment to cause a change in the neutral plane. |
Replacement
of a diode also requires balancing of the rotor with a one-piece rotor
lamination to be shrunk fit and keyed to the shaft. |
|
B |
Before
touching a small capacitor connected to a de-energized circuit, or
even one that is completely disconnected, you should do what FIRST? |
gently tap
the body with a screwdriver |
short
circuit the terminals to make sure that the capacitor is discharged |
tag it with
a de-energized tag |
be equipped
with an insulated fuse puller |
|
C |
Which type
of flux should be used when soldering electrical wire connections for
electronic components on printed circuit boards? |
Solid flux |
Silver flux |
Rosin flux |
Acid flux |
|
D |
If a
delicate component must be soldered into a circuit, how can the
component be protected from the heat of the soldering process? |
pre-oxidizing the leads to be soldered |
coating the
leads to be soldered with a light oil film |
operating
the soldering gun not more than 60 seconds at a time |
using a
thermal shunt heat sink |
|
C |
Two
contributors of electronic console failures are heat and vibration. To
combat some of their effects, what should be included in performing
preventive maintenance procedures? |
daily
inspection of console foundation bolts |
unplugging
of all circuit cards and reseating on a daily basis |
periodic
changing or cleaning of console ventilation and control room air
conditioning filters |
systematic
rotation of circuit cards with those from spares to allow component
cooling |
|
C |
A capacitor
is to be tested with a digital multimeter set up to measure ohms. If
the meter is connected to a shorted capacitor, how would the meter
display respond? |
immediately
display a value of OL with the value then continuously dropping to a
low value |
immediately
display a value of OL which remains at OL |
immediately
display a very low resistance value which remains low |
immediately
display a very low resistance with the value then continuously rising
to a value of OL |
|
D |
What should
be done with a capacitor that is obviously discolored due to excessive
heat? |
cooled with
a spray can of refrigerant approved for this purpose |
calibrated
using a capacitance Wheatstone bridge |
resoldered
with care taken to insure that the original cold solder joint is
repaired |
replaced and
the reason for the overheating found |
|
B |
What is the
name of the device shown in figure "2" of the illustration?
Illustration EL-0068 |
rectifier
bridge |
power
rectifier diode |
light-emitting diode |
silicon-controlled rectifier |
|
D |
If a digital
multimeter is set up as shown in figures "A" and "B" of the
illustration, what is the status of the silicon diode if the display
reads OL ohms when configured as in figure "A" and reads OL ohms when
configured as in figure "B"? Illustration EL-0211 |
the diode is
intermittently open |
the diode is
shorted |
the diode is
functioning properly |
the diode is
open |
|
C |
If a digital
multimeter is set up as shown in figures "A" and "B" to test a silicon
diode, what is the status of the diode if the screen displays OL V
when configured as in figure "A" and displays OL V when configured as
in figure "B"? Illustration EL-0212 |
diode is
operating properly |
diode is
intermittently open |
diode is
open |
diode is
shorted |
|
B |
If a digital
multimeter is set up as shown in figure "A" of the illustration to
test a capacitor, what would the display read if the capacitor is
shorted? Illustration EL-0213 |
the ohmic
value would read very high (OL ohms) and remain at that value |
the ohmic
value would read very low and remain at that value |
the ohmic
value would initially read very low, but over time the ohmic value
would gradually rise to an extremely high value (OL ohms) |
the ohmic
value would initially read very high (OL ohms), but over time the
ohmic value would gradually drop to an extremely low value |
|
B |
If a digital
multimeter is set up as shown in figure "B" of the illustration to
test a capacitor, what would the display read if the capacitor was
functioning properly? Illustration EL-0213
" |
initially a
very low ohmic value will be displayed, followed by a gradual rise in
resistance until a very high value is displayed (OL ohms) |
the actual
capacitance value of the capacitor will be displayed which should be
within the tolerance range of the capacitor |
initially a
very high ohmic value will be displayed (OL ohms), followed by a
gradual drop in resistance until a very low value is displayed |
the charging
voltage would be displayed which will initially be low and gradually
rise to the internal battery voltage |
|
A |
Which of the
following conditions would most likely lead to the failure of a
resistor due to overheating? |
Resistor
wattage rating one half that required for the circuit. |
Resistor
wattage rating two times higher than that required for the circuit. |
Resistor
wattage rating four times higher than that required for the circuit. |
Resistor
wattage rating equal to that required for the circuit. |
|
B |
What would
be the indication of a burned-out LED? |
excessive
output |
no
illumination |
excessive
illumination |
a slight
glow in the crystal |
|
D |
When
troubleshooting electronic equipment, why should you use a high
impedance multimeter? |
for AC
measurements only and a low resistance meter for DC measurements |
whenever a
low impedance meter is not available, regardless of the components
being tested |
to prevent
excess current flow through the meter that would damage it |
so as not to
load down the circuit and obtain erroneous voltage readings |
|
C |
Concerning
the illustrated fire detection and alarm system, when the system is
operating normally and under supervision, what is the status of the
ground detector and the fire alarm relays? Illustration EL-0114 |
The ground
detector relay is energized and the fire alarm relay is de-energized. |
Both the
ground detector and the fire alarm relays are both de-energized. |
The ground
detector relay is de-energized and the fire alarm relay is energized. |
Both the
ground detector and the fire alarm relays are both energized. |
|
A |
Referring to
the illustration pertaining to an alternator protection and alarm
system, what statement is true concerning the component labeled "LO"?
Illustration EL-0067 |
LO is an
alternator electrical fault trip master lock-out and alarm device. |
LO is an
alternator bearing low lube oil pressure safety shutdown and alarming
device. |
LO is an
alternator prime mover low lube oil pressure safety shutdown and
alarming device. |
LO is an
alternator phase loss safety shutdown and alarming device. |
|
A |
Referring to
the illustration pertaining to the semiautomatic navigation light
panel circuit, if the buzzer sounds and the masthead indicator light
comes on, what statement is true concerning acknowledging and
responding to the alarm while minimizing the danger to navigation?
Illustration EL-0108 |
The buzzer
is immediately silenced by turning the masthead transfer switch in the
line section to the secondary lamp position. The masthead light will
then immediately illuminate. |
The buzzer
cannot be silenced and the masthead light cannot be illuminated until
the burned out masthead lamp is replaced. |
The buzzer
is immediately silenced by turning the master switch in the master
section off. The masthead light can only be illuminated by replacing
the burned out bulb. |
The buzzer
is immediately silenced by turning the masthead transfer switch in the
line section off. The masthead light can only be illuminated by
replacing the burned out bulb. |
|
C |
In an
impressed current cathodic hull protection system, what statement is
true concerning the composition and arrangement of the anodes? |
The
protective anodes are made of zinc and are electrically insulated from
the hull. |
The
protective anodes are made of lead or platinized titanium and are
electrically bonded to the hull. |
The
protective anodes are made of lead or platinized titanium and are
electrically insulated from the hull. |
The
protective anodes are made of zinc and are electrically bonded to the
hull. |
|
C |
While
monitoring an impressed current cathodic hull protection system, which
of the following measurements should remain constant in a properly
operating electronically regulated system? |
Control
amplifier output voltage |
Individual
anode currents |
Reference
electrode voltage |
Total anode
current |
|
A |
Referring to
the impressed current cathodic hull protection system shown in the
illustration, if required to control the impressed current to the
anodes manually by using the hand adjustment potentiometer, what
parameter should be maintained at a constant value? Illustration
EL-0090 |
Reference
control voltage |
Individual
anode currents |
Control
amplifier output voltage |
Total anode
current |
|
C |
In
monitoring an impressed current cathodic hull protection system, it is
important to insure that the propeller screw receive the same cathodic
protection as the hull. What should be checked for? |
No checks
are necessary since the propeller screw is bronze and needs no
protection. |
Nothing can
be done short of checking the propeller screw at dry-dock
availabilities. |
Insure
adequate grounding carbon brush pressure on the rotating shaft and
check brushes for wear. |
Insure
adequate individual anode current to the anode closest to the
propulsion shafting as it passes through the hull. |
|
A |
Referring to
the impressed current cathodic protection system shown in the
illustration, if required to control the current to the anodes
manually by using the hand adjustment potentiometer, what statement
best represents the changes that should prompt one to recheck the
reference electrode voltage (hull potential)? Illustration EL-0090 |
Changes in
vessel speed, sea water temperature, and sea water salinity should all
prompt rechecking. |
Changes in
sea water temperature and vessel speed should all prompt rechecking.
Changes in sea water temperature need not prompt rechecking. |
Changes in
sea water temperature and sea water salinity should all prompt
rechecking. Changes in vessel speed need not prompt rechecking. |
Changes in
sea water salinity and vessel speed should all prompt rechecking.
Changes in sea water temperature need not prompt rechecking. |
|
B |
When the
control handle is in the 'off' position, what is the status of the
solenoid actuated brake of an electric winch? |
energized
and the brake is released |
de-energized
and the brake is set by a spring |
energized
and the brake is set by a spring |
de-energized
and the brake is released |
|
D |
In the event
of a power failure during cargo loading operations, the movement of an
electric powered cargo winch will be stopped by what means? |
a manual
override switch |
a hand
operated band brake |
the weight
of the load on the boom |
a spring set
brake |
|
A |
What type of
motor is used in the AC hoist controller as shown in the illustration?
Illustration EL-0102 |
wound rotor
induction motor |
synchronous
motor |
stepper
motor |
squirrel
cage induction motor |
|
A |
What
statement is true concerning the 'MS 1' contacts of the master switch
shown in the illustration? Illustration EL-0102 |
They are
closed only when the master switch is 'off'. |
They are
closed only when the master switch is selected for a 'lower' position. |
They are
closed only when the master switch selected for a 'hoist' position. |
They are
opened only when the master switch is 'off'. |
|
C |
What is the
functional purpose of the 'LSL' contacts for the hoist controller
circuit shown in the illustration? Illustration EL-0102 |
It is a
limit switch which illuminates a warning light to warn the winch
operator when the hoist block is approaching the boom |
It is a
limit switch which illuminates a warning light to warn the winch
operator when the cable has only a few wraps on the drum while paying
out |
It is a
limit switch which automatically stops the winch drum rotation in the
lower direction before all the cable is payed out insuring that a few
wraps remain on the drum |
It is a
limit switch which automatically stops the winch drum rotation in the
hoist direction before the hoist block is able to strike the boom |
|
C |
What is the
functional purpose of the 'MS 2' contacts in the hoist controller
circuit shown in the illustration? Illustration EL-0102 |
The 'MS 2'
contacts are used to select for 'second point' hoisting and lowering |
The 'MS 2'
contacts are used to select for 'first point' hoisting and lowering |
The 'MS 2'
contacts are not used in this particular application |
The "MS 2'
contacts are used for resetting the under voltage (UV) contactor |
|
A |
As shown in
the illustration, how are the rotor windings of the motor configured?
Illustration EL-0102 |
wye |
delta |
series-parallel |
open delta |
|
A |
Which of the
listed conditions occur when selection is made for 'third point hoist'
on the winch hoist controller shown in the illustration? Illustration
EL-0102 |
Master
switch contacts "4","5", and "6" close. |
Contactors
'H', '1A' and '2A' drop out. |
Master
switch contacts "4","7", and "8" close. |
Contactors
'H, '3A', '4A' pick up. |
|
A |
As shown in
the illustration, what is responsible for maintaining the "UV" relay
energized when the master switch handle is moved away from the "off"
position? Illustration EL-0102 |
normally
open 'UV' contacts |
MS 2'
contacts |
MS 1'
contacts |
normally
closed 'OL' contacts |
|
B |
What is the
name of the mechanism used to transmit rudder angle information from
the steering gear itself to the wheelhouse in the illustrated rudder
angle indicator system? Illustration EL-0092 |
telemotor |
synchronous
transmission |
differential
gear |
gear
transmission |
|
A |
When power
is restored after a complete power failure, how will the steering gear
pump motor which was on-line respond? |
It will
restart automatically |
It will have
to be reset manually |
It will have
to be restarted manually |
It will trip
its overload relays |
|
B |
As shown in
figure "A" of the illustration, the actual rudder angle repeatback
signal originates at what device and is delivered to what other
device? Illustration EL-0097 |
originates
at the amplifier and delivered to the control potentiometer |
originates
at the power unit and delivered to the amplifier |
originates
at the power unit and delivered to the control potentiometer |
originates
at the amplifier and delivered to the power unit |
|
C |
What does
figure "C" of the illustration represent? Illustration EL-0092 |
a
synchronous transmission system with two transmitters and a single
receiver each equipped with a single phase rotor winding and a three
phase stator winding |
a
synchronous transmission system with two transmitters and a single
receiver each equipped with a single phase stator winding and a three
phase rotor winding |
a
synchronous transmission system with a single transmitter and two
receivers each equipped with a single phase stator winding and a three
phase rotor winding |
a
synchronous transmission system with a single transmitter and two
receivers each equipped with a single phase rotor winding and a three
phase stator winding |
|
C |
If coil
'R1-R2-R3' on the transmitter in figure "C" shown in the illustration
is turned 30 degrees clockwise, how will the corresponding coils
'R1-R2-R3' on the receivers (indicators) respond? Illustration EL-0092 |
receive a
lower voltage depending on the turns ratio |
receive a
higher voltage depending on the turns ratio |
torque will
cause them to align to the same position |
ring at the
receiving station until the turning stops |
|
C |
In actual
applications, electrical connections associated with 'R1, R2 and R3'
of the transmitter to 'R1, R2, and R3' of the indicators shown in
figure "C" of the illustration are made by what means? Illustration
EL-0092 |
soldered
contacts |
spliced and
taped connections |
slip rings
and brushes |
solderless
crimp-on connectors |
|
C |
What is the
name of the mechanism used to transmit torque angle over distance in
the illustrated rudder angle indicator system? Illustration EL-0092 |
telemotor |
differential
gear |
synchronous
transmission |
gear
transmission |
|
D |
The
electrical energy necessary to power a sound-powered telephone's small
vibrating bell is obtained from what power source? |
the
emergency batteries for the general alarm |
normal 115
volt DC supplies |
the
emergency switchboard |
each
station's hand-cranked generator |
|
C |
What type of
equipment does the wiring diagram shown in the illustration represent?
Illustration EL-0093 |
engine speed
tachometer with repeaters |
rudder angle
indicator arrangement |
sound
powered telephone system |
engine order
telegraph circuit |
|
A |
Referring to
the sound-powered telephone circuit shown in the illustration, in what
component are the sound-powered transmitter and receiver units
located? Illustration EL-0093 |
A |
B |
C |
D |
|
A |
Referring to
the sound-powered telephone circuit shown in illustration, what
statement is true concerning the button on the handset as represented
by the component labeled "A"? Illustration EL-0093 |
The
push-button is depressed for the purposes of listening and talking. |
The
push-button is depressed only for the purposes of listening, and it
should be released for talking. |
The
push-button is depressed only for the purposes of conversing with
multiple stations. For a conversation between two stations, it is not
needed. |
The
push-button is depressed only for the purposes of talking, and it
should be released for listening. |
|
D |
Which of the
following expresses the relationship of the AC input frequency and DC
ripple output frequency in a full wave rectifier? |
The output
ripple frequency is the same as input frequency. |
The output
ripple frequency is four times the input frequency. |
The output
ripple frequency is one-half the input frequency. |
The output
ripple frequency is twice the input frequency. |
|
B |
What does
section "C" of the circuit shown in the illustration function as?
Illustration EL-0085 |
a rectifier |
a filter |
a voltage
regulator |
a voltage
transformer |
|
A |
The
transistors in figure "B" the illustrated circuit are connected using
what type of coupling? Illustration EL-0048 |
RC coupling |
LC coupling |
transformer
coupling |
direct
coupling |
|
D |
In figure
"A" of the illustration, the battery Vbb and resistor Rb are in the
circuit for what purpose? Illustration EL-0022 |
to apply a
buffer between the input ground and the emitter ground |
to apply a
reverse bias to the emitter-base |
to apply a
'reference charge' on the input capacitor |
to apply a
forward bias to the emitter-base |
|
B |
In figure
"A" of the illustrated circuit, the amplifier is connected in what
basic configuration? Illustration EL-0045 |
Darlington
paired, capacitor coupled |
common
emitter |
common
collector |
common base |
|
C |
As shown in
figure "C" of the illustration, what are the purposes of the coupling
capacitor Cc and the bypass capacitor Cbp respectively __________.
Illustration EL-0045 |
Cc blocks
any AC component associated with the input from reaching the base Cbp
helps minimize degeneration of the AC output signal |
Cc blocks
any DC component associated with the input from reaching the base Cbp
helps maximize degeneration of the AC output signal |
Cc blocks
any DC component associated with the input from reaching the base Cbp
helps minimize degeneration of the AC output signal |
Cc blocks
any AC component associated with the input from reaching the base Cbp
helps maximize degeneration of the AC output signal |
|
C |
As shown in
figure "A" of the illustration, what type of converter unit is
represented? Illustration EL-0240 |
de-multiplexer |
digital to
analog converter |
analog to
digital converter |
multiplexer |
|
A |
As shown in
figure "B" of the illustrated function block for a PLC PID controller,
to what input is the actual analog signal of the measured value
delivered? Illustration EL-0251 |
PV |
KP |
XO |
SP |
|
A |
If the clock
frequency input to the circuit shown in the illustration were 2 kHz,
what would be indicated at the output of 'FF-3' at the Q3 output?
Illustration EL-0087 |
125 Hz |
1 kHz |
500 Hz |
250 Hz |
|
B |
What is the
name of the digital logic gate represented by figure "1" of the
illustration? Illustration EL-0035 |
Exclusive OR
gate |
OR gate |
NOR gate |
AND gate |
|
D |
On a digital
numerical display readout, what would be the minimum number of LED
segments required to form and display any digit 0 through 9? |
6 |
8 |
9 |
7 |
|
D |
As shown in
figure "A" of the illustration, what is the configuration of the
operational amplifier? Illustration EL-0252 |
differential
amplifier |
non-inverting amplifier |
summing
amplifier |
inverting
amplifier |
|
D |
In process
control terminology, continuously variable values which change without
distinct increments, such as temperature, pressure, or level are
correctly referred to as what type of values? |
binary
values |
bumpless
values |
digital
values |
analog
values |
|
C |
As shown in
figure "B" of the illustrated block diagram of the signal processing
flow path, what does the block "TRANSDUCER" represent? Illustration
EL-0095 |
These are
sensing and transmitting devices designed to sense and measure a
physical parameter and convert it to a proportional digital electrical
signal. |
These are
sensing and transmitting devices designed to sense and measure a
physical parameter and convert it to a proportional electromechanical
force. |
These are
sensing and transmitting devices designed to sense and measure a
physical parameter and convert it to a proportional analog electrical
signal. |
These are
sensing and transmitting devices designed to sense and measure a
physical parameter and convert it to a proportional pneumatic signal. |
|
C |
As shown in
the illustrated block diagram for a distributed automation system,
what statement is true concerning the area networks? Illustration
EL-0096 |
The LAN is a
single non-redundant network and the partitioned CAN is a dual
redundant network, with both networks being interconnected. |
The LAN is a
dual redundant network and the partioned CAN is also a dual redundant
network, with no interconnectivity between the two networks. |
The LAN is a
dual redundant network and the partitioned CAN is also a dual
redundant network, with both networks being interconnected. |
The LAN is a
single non-redundant network and the partioned CAN is a dual redundant
network, with no interconnectivity between the two networks. |
|
D |
As shown in
figures "A", "B", and "C" of the illustration, what is the purpose of
the differential amplifier segment of the 741 operational amplifier?
Illustration EL-0111 |
detect and
amplify the voltage difference between the inputs at pins 1 and 5 |
detect and
amplify the voltage difference between the inputs at pins 1 and 2 |
detect and
amplify the voltage difference between the inputs at pins 3 and 5 |
detect and
amplify the voltage difference between the inputs at pins 2 and 3 |
|
A |
As shown in
the illustration, which electrical symbol represents a PNP type
bipolar junction transistor? Illustration EL-0065 |
1 |
2 |
3 |
4 |
|
D |
As shown in
figure "A" of the illustration, what is true concerning the
illustrated frequency response curve? Illustration EL-0076 |
Low
frequencies below the cutoff-frequency are attenuated and high
frequencies above the cut-off frequency are attenuated. |
Low
frequencies below the cutoff-frequency are passed and high frequencies
above the cutoff frequency are attenuated. |
Low
frequencies below the cutoff-frequency are passed and high frequencies
above the cutoff frequency are passed. |
Low
frequencies below the cutoff-frequency are attenuated and high
frequencies above the cut-off frequency are passed. |
|
D |
Which of the
listed conditions describes the effect on intrinsic semiconductor
operation as a result of a temperature increase? |
Inductive
reactance will decrease |
Resistivity
will increase |
Capacitive
reactance will decrease |
Conductivity
will increase |
|
A |
What does
the electronic symbol of figure "9" represent? Illustration EL-0065 |
triac
thyristor |
zener diode |
diac trigger
diode |
diode
rectifier |
|
A |
As shown in
figure "A" of the illustration, under what conditions will the
thyristor conduct? Illustration EL-0154 |
when the
anode is more positive than the cathode and when the gate is briefly
pulsed with a voltage more positive than the cathode |
when the
anode is more negative than the cathode and when the gate is briefly
pulsed with a voltage more positive than the cathode |
when the
anode is more positive than the cathode and when the gate is briefly
pulsed with a voltage more negative than the cathode |
when the
anode is more negative than the cathode and when the gate is briefly
pulsed with a voltage more negative than the cathode |
|
C |
What is the
functional purpose of a heat sink, as frequently used with
transistors? |
to increase
the reverse current |
to
compensate for excessive doping |
to prevent
excessive temperature rise |
to decrease
the forward current |
|
D |
What is the
third color band on a resistor used to indicate? |
tolerance of
the resistor |
second
significant figure of the resistance |
first
significant figure of the resistance |
number of
zeros following the first two significant figures in the resistance
value |
|
D |
A
saturable-core reactor operates on the principle of controlling a load
winding's inductance by changing the permeability of the core. How is
this accomplished? |
varying the
core's inductance |
varying the
core's dielectric strength |
varying the
core's reactance |
varying the
core's saturation |
|
B |
What will
happen to a carbon resistor operating in electrical equipment that is
NOT properly cooled?
o |
it will
change its value inversely proportional to the amount of heat
generated and time in
service |
its
reliability factor will decrease |
its
reliability factor will increase |
it will
always operate at the same ohmic value |
|
B |
A carbon
resistor has a resistance of 50 ohms, and a tolerance of 5 percent.
What would be the respective colors indicated for bands 1, 2, 3 and 4
for this resistor as shown in figure "A" of the illustration?
Illustration EL-0103 |
green,
black, black, and silver. |
green,
black, black, and gold. |
gray, black,
brown, and silver. |
gray, black,
brown, and gold. |
|
A |
Which of the
procedures or conditions listed could result in damaging a transistor
beyond repair? |
Providing
incorrect polarity to the collector circuit. |
Installing a
transistor whose current rating exceeds the design circuit current. |
Providing
insufficient voltage to the input circuit. |
Applying
silicone grease between the heat sink and the transistor mounting. |
|
B |
An ohmmeter
used to test for front-to-back resistance of a PN junction diode
should produce roughly what ratio? |
1000:1 |
100:1 |
500:1 |
5000:1 |
|
B |
If a digital
multimeter is set up as shown in figure "A" of the illustration to
test a capacitor, what would the display read if the capacitor is
functioning properly? Illustration EL-0213
" |
the ohmic
value would read very low and remain at that value |
the ohmic
value would initially read very low, but over time the ohmic value
would gradually rise to an extremely high value (OL ohms) |
the ohmic
value would initially read very high (OL ohms), but over time the
ohmic value would gradually drop to an extremely low value |
the ohmic
value would read very high (OL ohms) and remain at that value |
|
C |
What should
be done with a capacitor that is obviously discolored due to excessive
heat? |
calibrated
using a capacitance Wheatstone bridge |
cooled with
a spray can of refrigerant approved for this purpose |
replaced and
the reason for the overheating found |
resoldered
with care taken to insure that the original cold solder joint is
repaired |
|
D |
If a digital
multimeter is set up as shown in figures "A" and "B" to test a silicon
diode, what is the status of the diode if the screen displays 0.70 V
when configured as in figure "A" and displays OL V when configured as
in figure "B"? Illustration EL-0212 |
diode is
open |
diode is
intermittently open |
diode is
shorted |
diode is
operating properly |
|
D |
In order to
check the performance of a transistor removed from its circuit, what
meter or tester should be used? |
impedance
meter |
sensitive
potentiometer |
voltmeter or
transistor tester |
ohmmeter or
transistor tester |
|
A |
Which of the
following conditions would most likely lead to the failure of a
resistor due to overheating? |
Resistor
wattage rating one half that required for the circuit. |
Resistor
wattage rating four times higher than that required for the circuit. |
Resistor
wattage rating two times higher than that required for the circuit. |
Resistor
wattage rating equal to that required for the circuit. |
|
B |
What would
be the indication of a burned-out LED? |
excessive
illumination |
no
illumination |
excessive
output |
a slight
glow in the crystal |
|
A |
Which of the
substances listed can be used to shield sensitive equipment from
static magnetic fields? |
Permeable
iron |
Bakelite |
Mica |
Glass |
|
D |
When placed
in a magnetic field, which of the materials listed will maintain the
highest permeability? |
Bakelite |
Glass |
Aluminum |
Soft iron |
|
D |
Which of the
following statements concerning analog and digital devices is correct? |
There are no
basic differences between the two systems. |
Analog
devices are superior in accuracy compared to digital devices. |
Operations
in a digital device are performed simultaneously. |
The
variables in digital systems are fixed quantities, and the variables
in analog systems are continuous quantities. |
|
C |
The
multiplier prefix 'giga' (G) such as used in "gigabytes" represents
what multiplication factor? |
thousand (10
to the 3rd power) |
million (10
to the 6th power) |
billion (10
to the 9th power) |
trillion (10
to the 12th power) |
|
A |
Which of the
wave shapes shown in the illustration is termed a sinusoidal wave?
Illustration EL-0088 |
A |
B |
C |
D |
|
B |
Which line
in figure "B" shown in the illustration represents the trailing edge
of the wave? Illustration EL-0088 |
3 |
4 |
5 |
6 |
|
B |
As shown in
the illustrated harmonic analysis diagram, which figure represents the
fundamental (or first harmonic)? Illustration EL-0163 |
A |
B |
C |
D |
|
B |
What is the
name of the semiconductor that decreases in resistance with an
increase in temperature? |
thermopile |
thermistor |
diode |
resistor |
|
B |
Which of the
following statements correctly applies to bipolar junction
transistors? |
The emitter
separates the base and collector. |
The three
terminals are called the emitter, base, and collector. |
The
collector separates the emitter and base. |
LED and LCD
are the two basic types of transistors. |
|
D |
Which of the
pictured solid state semiconductor devices is a light-emitting diode?
Illustration EL-0068 |
1 |
2 |
4 |
7 |
|
A |
What does
the symbol in figure "1" shown in the illustration represent?
Illustration EL-0065 |
PNP bipolar
junction transistor |
silicon
controller rectifier |
NPN bipolar
junction transistor |
junction
field effect transistor |
|
B |
What is the
name of the component labeled CR1 as shown in section "D" of the
regulated DC power supply illustrated? Illustration EL-0085 |
rectifier
diode |
zener diode |
tunnel diode |
diac |
|
B |
A silicon
controlled rectifier (SCR) is a solid state device used for what
functional purpose? |
functions
like an amplifier and controls relatively high load current |
functions
like a switching device and controls relatively high load current |
functions
like an amplifier and controls relatively low load current |
functions
like a switching device and controls relatively low load current |
|
B |
In what
applications are germanium semiconductor diodes commonly used? |
potentiometers |
rectifiers |
power
sources |
photocells |
|
D |
In comparing
a semiconductor diode to a vacuum tube diode, what statement is true? |
The
semiconductor diode has longer life, no warm-up time, and is more
delicate than the vacuum tube diode. |
The
semiconductor diode has longer life, longer warm-up time and is less
delicate than the vacuum tube diode. |
The
semiconductor diode has shorter life, no warm-up time, and is less
delicate than the vacuum tube diode. |
The
semiconductor diode has longer life, no warm-up time, and is less
delicate than the vacuum tube diode. |
|
A |
What is the
functional purpose of the resistor 'RL" placed in parallel to the
output of a DC power supply as shown in section "D" of the regulated
DC power supply? Illustration EL-0085 |
aids in
output voltage regulation |
corrects
power factor |
is a
temperature compensator |
prevents
excessive currents |
|
A |
Which of the
following statements represents an application of a silicon controlled
rectifier? |
Provides DC
power for a main propulsion motor. |
Used in
photo cell sensor circuits for boiler burners. |
Used as a
voltage reference diode. |
Used to
eliminate AC power supply hum. |
|
A |
Silicon
diodes which are designed for a specific reverse breakdown voltage,
and are most often used as electronic power supply voltage regulators,
are specifically what type of diode? |
Zener diodes |
hot-carrier
diodes |
tunnel
diodes |
compensating
diodes |
|
C |
A
common-emitter circuit has an input voltage of 0.1 volt, an output
voltage of 2.0 volts, an input current of 0.5 milliamps, and an output
current of 10 milliamps. What is the power gain? |
20 |
40 |
400 |
4000 |
|
B |
A signal
derived from an amplifier output and returned to the amplifier input
is called what type of signal? |
monitoring
signal |
feedback
signal |
reverse
signal |
inverse
signal |
|
C |
What is the
name for the device shown in figure "A" of the illustration?
Illustration EL-0064 |
direct
current (DC) filter |
full wave
bridge rectifier |
half wave
rectifier |
full wave
rectifier |
|
A |
What does
the circuit shown in the illustration represent? Illustration EL-0085 |
regulated DC
power supply |
a Wheatstone
bridge |
a waveform
analyzer |
a magnetic
amplifier |
|
A |
In which
section of the 24 VDC power supply circuit illustrated does the
greatest change in voltage level take place when fed from 120 VAC
ship's power? Illustration EL-0085 |
A |
B |
C |
D |
|
B |
What is the
correct term for the fluctuation of voltages in figure "H" shown in
the illustration? Illustration EL-0085 |
swell |
ripple |
wave |
roll |
|
A |
The
component labeled 'CR1' in the circuit shown in the illustration
serves what functional purpose? Illustration EL-0085 |
it
establishes a constant reference voltage for the base of 'Q1' |
it acts as a
low capacitive reactance to smooth ripple |
it varies
its anode/cathode polarity depending on 'RL' current |
it rectifies
the varying voltage from the collector of 'Q1' |
|
B |
An voltage
amplifier has a calculated voltage gain of 5. Which statement is true
concerning input and output voltages? |
If the input
changes10 volts, the output changes 2 volts. |
If the input
changes 2 volts, the output changes 10 volts. |
If the input
changes 10 volts, the output changes 5 volts. |
If the input
changes 5 volts, the output changes 10 volts. |
|
D |
How are
operational amplifiers, used primarily in analog circuits,
characterized? |
low input
impedance, low gain and high output impedance |
high input
impedance, high gain and high output impedance |
low input
impedance, high gain and low output impedance |
high input
impedance, high gain and low output impedance |
|
A |
In referring
to figure "E" of the illustration, what statement is true concerning
the functional purpose of the coupling transformer? Illustration
EL-0075 |
The
transformer functions as a filter by removing the DC component from
the varying DC input to produce an AC output shifted 90o from the
input. |
The
transformer functions as a filter by removing the DC component from
the varying DC input to produce an AC output in phase with the input. |
The
transformer functions as a voltage transformer by changing the
magnitude of the peak to peak AC voltage at the output proportional to
the turns ratio. |
The
transformer functions as a filter by removing the DC component from
the varying DC input to produce an AC output shifted 180o from the
input. |
|
A |
As shown in
the illustrated block diagram for a distributed automation system,
what statement is true concerning the workstations labeled "LOS"
associated with the port power management system? Illustration EL-0096 |
These are
local operating system workstations that allow local control of
processes related to the operation and control of the port generator. |
These are
lube oil system workstations that allow local control of processes
related to the lubrication of all machinery within the engineering
plant. |
These are
lube oil system workstations that allow local control of processes
related to the lubrication of the port generators. |
These are
local operating system workstations that allow local control of
processes related to the operation and control of all functions within
the engineering plant. |
|
C |
In referring
to figure "F" of the illustration, what statement is true concerning
the functional purpose of the RC coupling? Illustration EL-0075 |
The RC
coupling functions as a filter by removing the DC component from the
varying DC input to produce an AC output shifted 90o from the input. |
The RC
coupling functions as a filter by removing the DC component from the
varying DC input to produce an AC output shifted 180o from the input. |
The RC
coupling functions as a filter by removing the DC component from the
varying DC input to produce an AC output in phase with the input. |
The RC
coupling functions as a voltage transformer by changing the magnitude
of the peak to peak AC voltage at the output proportional to the RC
time constant. |
|
C |
As shown in
the illustrated block diagram for a distributed automation system,
what statement is true concerning the units labeled "ROS" which are
remote operating system workstations? Illustration EL-0096 |
Operator
access to control functions among the various ROS locations are all
identical. |
The ROS
located in the wheelhouse is designated as the master ROS. |
Operator
access to control functions among the various ROS locations differ
depending system configuration and need. |
The ROS
located in the ship's office is designated as the master ROS. |
|
C |
In referring
to the graphs shown in the illustration, which of the following
figures represents a band pass filter? Illustration EL-0076 |
A |
B |
C |
D |
|
A |
In referring
to figure "A" of the illustration, what type of active filter circuit
is shown? Illustration EL-0077 |
Low-pass
filter circuit |
High-pass
filter circuit |
Notch filter
circuit |
Band-pass
filter circuit |
|
C |
As shown in
the illustrated block diagram for a programmable logic controller
system, in what functional component is the program developed and used
to transfer the program to the memory unit of the PLC? Illustration
EL-0225 |
communications interface |
program and
data memory |
programming
device |
processor |
|
C |
As shown in
figure "A" of the illustrated PLC sub-circuit, what type of circuit is
depicted? Illustration EL-0230 |
AC output
unit |
AC input
unit |
DC input
unit |
DC output
unit |
|
B |
As shown in
all four diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0226 |
OR gate |
AND gate |
NAND gate |
NOR gate |
|
C |
As shown in
figure "A" of the illustration, what input conditions are required to
produce an output? Illustration EL-0241 |
Both "Input
1" and "Input 2" must be closed OR both "Input 3" and "Input 4" must
be closed. o |
Both "Input
1 and "Input 2" must be closed AND either "Input 3" or "Input 4" must
be closed. |
Either
"Input 1" or "Input 2" must be closed OR both "Input 3" and "Input 4"
must be closed. |
Either
"Input 1" or "Input 2" must be closed AND either "Input 3" or "Input
4" must be closed. |
|
B |
As shown in
all four diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0227 |
NOR gate |
OR gate |
AND gate |
NAND gate |
|
D |
As shown in
figure "C" of the illustration, what type of timer is represented?
Illustration EL-0242 |
on-off delay
timer |
pulse timer |
off-delay
timer |
on-delay
timer |
|
B |
As shown in
all four diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0233 |
AND gate |
NAND gate |
NOR gate |
OR gate |
|
C |
As shown in
all four diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0234 |
NAND gate |
OR gate |
NOR gate |
AND gate |
|
D |
As shown in
all four diagrams included in the illustration, what type of logic
circuit is represented? Illustration EL-0231 |
NOT gate |
OR gate |
NOR gate |
XOR gate |
|
D |
Referring to
figure "1" of the illustration, what type of logic gate is symbolized?
Illustration EL-0035 |
NOR gate |
XOR gate |
AND gate |
OR gate |
|
C |
Referring to
figure "2" of the illustration, what type of logic gate is symbolized?
Illustration EL-0035 |
OR gate |
XOR gate |
NOR gate |
AND gate |
|
A |
Referring to
figure "3" of the illustration, what type of logic gate is symbolized?
Illustration EL-0035 |
AND gate |
XOR gate |
NOR gate |
OR gate |
|
C |
Referring to
figure "4" of the illustration, what type of logic gate is symbolized?
Illustration EL-0035 |
NOR gate |
AND gate |
NAND gate |
XOR gate |
|
A |
Referring to
figure "5" of the illustration, what type of logic gate is symbolized?
Illustration EL-0035 |
XOR gate |
NOR gate |
AND gate |
OR gate |
|
C |
How should
the shunt used in an ammeter be connected? |
in parallel
with the load and in series with the meter movement |
in series
with the load and in series with the meter movement |
in series
with the load and in parallel with the meter movement |
in parallel
with the load and in parallel with the meter movement |
|
C |
Why are
external shunts sometimes used with ammeters? |
to increase
meter sensitivity |
to permit
shunts with larger resistances to be utilized |
to prevent
damage to the meter movement from heat generated by the internal shunt |
to reduce
reactive power factor error |
|
C |
The clamp-on
AC ammeter consists essentially of a split-core and a rectifier-type
instrument connected to the secondary winding of a particular type of
transformer. Which type is used? |
reactance
transformer |
potential
transformer |
current
transformer |
control
transformer |
|
A |
To properly
use a clamp-on-type ammeter to check current flow, what must be done
FIRST? |
hook the
jaws of the instrument around the insulated single conductor |
short the
test leads and calibrate the instrument to zero |
connect the
voltage test leads to the appropriate terminals |
de-energize
the circuit to allow connection of the instrument in series |
|
C |
When a
resistor is used as a shunt and is connected in parallel with a meter
movement coil, what capability does this provide? |
a
measurement of circuit resistance |
an increased
accuracy of approximately 1.5 percent |
an extended
meter range |
this is
never done |
|
C |
What is the
instrument called a galvanometer used to measure? |
thickness of
galvanized metal |
quantity of
galvans in an electric circuit |
very small
amounts of current |
resistance
of electrical wiring insulation |
|
D |
Which of the
following electric meter movements uses a stationary permanent magnet
and movable coil? |
Electrodynamometer |
Inclined
coil iron-vane |
Moving
iron-vane |
D'Arsonval |
|
A |
To limit the
current flow through a DC voltmeter to as low a value as possible,
what is the moving coil circuit provided with? |
high series
resistance |
high
parallel resistance |
external
shunt |
series
inductor |
|
B |
How is a
wattmeter electrically connected in a circuit? |
In parallel |
In
series-parallel |
Inductively |
In series |
|
C |
In testing a
hand cranked megger prior to use, what statement is true? |
With the
test leads shorted or open, the pointer should go to infinite ohms. |
With the
test leads shorted or open, the pointer should go to zero ohms. |
With the
test leads shorted, the pointer should go to zero ohms, and with the
tests leads open, the pointer should go to infinite ohms. |
With the
test leads shorted, the pointer should go to infinite ohms, and with
the tests leads open, the pointer should go to zero ohms. |
|
C |
What is an
ammeter used to measure? |
the voltage
between two points in a circuit |
circuit
continuity |
current flow
in a circuit |
total or
partial circuit resistance |
|
C |
A digital
multimeter, set up as a milliammeter on the 100 milliamp scale, is
known to have an accuracy of plus or minus 2%. A display reading of
10.0 milliamps would indicate an actual line current between what two
values? |
9.8 and 10.0
milliamperes |
8.0 and 12.0
milliamperes |
9.8 and 10.2
milliamperes |
8.0 and 10.0
milliamperes |
|
D |
If a digital
multimeter set up to measure AC volts reads slightly above 'zero' when
its leads are disconnected, what is this a result of? |
definite
miscalibration of the meter |
capacitors
inside the meter storing charges |
a poor
ground for the meter case |
ghost'
voltages due to electromagnetic energy in the air |
|
D |
If you
disconnect and arrange both ends of a conductor of a multi-conductor
cable without any contact between the individual conductors, what
would a low ohmic value between the ends of a single conductor
indicate? |
the presence
of a partial ground |
an infinite
resistance |
that the
conductor is not short circuited |
continuity
of the conductor |
|
D |
Which of the
listed statements is correct when using a digital multimeter set up as
an ohmmeter? |
It is
usually not possible for a digital multimeter to be set up as an
ohmmeter. |
With the
test leads shorted together, a reading of 'OL' ohms will be displayed. |
With the
test leads apart insulated from each other, a reading of 'zero' ohms
will be displayed. |
With the
test leads shorted together, a reading of 'zero' ohms will be
displayed. |
|
A |
When testing
a capacitor with a digital multimeter set up as an ohmmeter, what
would be the indication on the display when testing an initially
discharged capacitor in good condition? |
the display
would immediately show very low resistance but gradually climb to 'OL' |
the display
would immediately show 'OL' ohms and remain at this value |
the display
would immediately show very low resistance but rapidly climb to a
slightly higher value and remain there |
the display
would immediately show very low resistance and remain at this value |
|
A |
While
troubleshooting a circuit in an engine room central control console, a
resistor is suspected of being faulty. Which of the following
precautions must be observed if an analog or digital multimeter set up
as an ohmmeter is to be used to check its value? |
Resistor's
circuit must be de-energized and at least one end of the resistor
isolated by disconnecting. |
Correct
polarity must be observed because reverse bias will damage the
component. |
Meter leads
must not be twisted so as to cancel out the individual magnetic
fields. |
The meter
case must be grounded prior to attaching the leads. |
|
D |
Prior to
using an analog multimeter set up as an ohmmeter, the leads are
purposely shorted together. Which of the following actions should be
taken if, when adjusting to 'zero' ohms, the indicating needle cannot
be returned to 'zero' on the scale? |
The test
reading should be added to each final reading. |
The lead
clips should be replaced. |
The test
reading should be subtracted from each final reading. |
The
batteries should be replaced. |
|
D |
Under what
circumstance would a hand-held portable phase sequence indicator be
used should the main switchboard mounted fixed phase sequence
indicator be inoperative? |
installing a
new synchroscope |
paralleling
alternators |
replacing a
defective solenoid |
preparing to
make the shore power connection |
|
B |
In what
situation would an electrical phase sequence indicator be useful? |
troubleshooting DC motors |
connecting
shore power lines to the ship |
preparing to
parallel alternators |
connecting
lighting branch circuits |
|
A |
Using the
portable harmonic analyzer shown in figure "A", if the clamp-on test
lead is connected as shown in figure "C" of the illustration, what is
being measured? Illustration EL-0110 |
the harmonic
content of the current of a single conductor at a service entrance |
the harmonic
content of the current of a bundle of conductors at a service entrance |
the harmonic
content of current leakage to hull ground |
the harmonic
content of the voltage at a service entrance |
|
C |
Periodic
testing using a special camera may be performed to detect potentially
dangerous loose or corroded bus bar and controller connections. What
is the name of this testing technology? |
corrosion
electrolysis |
electric
vibroanalysis |
heat
sensitive thermography |
visual
pyrotronics |
|
D |
An internal
resistance is placed in series with the meter movement of which of the
following instruments? |
AC frequency
meter |
AC ammeter |
DC ammeter |
DC voltmeter |
|
C |
When a
resistor is used as a shunt and is connected in parallel with a meter
movement coil, what capability does this provide? |
a
measurement of circuit resistance |
an increased
accuracy of approximately 1.5 percent |
an extended
meter range |
this is
never done |
|
C |
What is the
instrument called a galvanometer used to measure? |
resistance
of electrical wiring insulation |
quantity of
galvans in an electric circuit |
very small
amounts of current |
thickness of
galvanized metal |
|
B |
What is an
ohmmeter used to measure? |
voltage
between two points in a circuit |
circuit
resistance |
circuit
power |
the amount
of current flow in a circuit |
|
B |
What
practice could potentially damage a multimeter?
|
placing the
test leads in series with the load of a circuit to measure current
while in the voltmeter mode |
placing the
test leads across a voltage source to measure voltage while in the
resistance mode |
placing the
test leads across a de-energized and isolated resistance to measure
resistance while in the voltmeter mode |
placing the
test leads across a de-energized and isolated resistance to measure
resistance while in the ammeter mode |
|
B |
In what
situation would an electrical phase sequence indicator be useful? |
preparing to
parallel alternators |
connecting
shore power lines to the ship |
connecting
lighting branch circuits |
troubleshooting DC motors |
|
B |
What is the
circuit shown in the illustration used to measure? Illustration
EL-0024 |
battery
discharge rate in Amp-hours |
resistance |
gauss or
magnetic field strength |
capacitance |
|
C |
How should
the shunt used in an ammeter be connected? |
in series
with the load and in series with the meter movement |
in parallel
with the load and in series with the meter movement |
in series
with the load and in parallel with the meter movement |
in parallel
with the load and in parallel with the meter movement |
|
B |
Why are
external shunts sometimes used with ammeters? |
to reduce
reactive power factor error |
to prevent
damage to the meter movement from heat generated by the internal shunt |
to permit
shunts with larger resistances to be utilized |
to increase
meter sensitivity |
|
B |
What is an
ammeter used to measure? |
total or
partial circuit resistance |
current flow
in a circuit |
the voltage
between two points in a circuit |
circuit
continuity |
|
C |
The clamp-on
AC ammeter consists essentially of a split-core and a rectifier-type
instrument connected to the secondary winding of a particular type of
transformer. Which type is used? |
control
transformer |
reactance
transformer |
current
transformer |
potential
transformer |
|
D |
To properly
use a clamp-on-type ammeter to check current flow, what must be done
FIRST? |
de-energize
the circuit to allow connection of the instrument in series |
short the
test leads and calibrate the instrument to zero |
connect the
voltage test leads to the appropriate terminals |
hook the
jaws of the instrument around the insulated single conductor |
|
B |
If a digital
multimeter set up to measure AC volts reads slightly above 'zero' when
its leads are disconnected, what is this a result of? |
capacitors
inside the meter storing charges |
ghost'
voltages due to electromagnetic energy in the air |
definite
miscalibration of the meter |
a poor
ground for the meter case |
|
D |
Which of the
listed statements is correct when using a digital multimeter set up as
an ohmmeter? |
With the
test leads shorted together, a reading of 'OL' ohms will be displayed. |
With the
test leads apart insulated from each other, a reading of 'zero' ohms
will be displayed. |
It is
usually not possible for a digital multimeter to be set up as an
ohmmeter. |
With the
test leads shorted together, a reading of 'zero' ohms will be
displayed. |
|
A |
When testing
a capacitor with a digital multimeter set up as an ohmmeter, what
would be the indication on the display when testing an initially
discharged capacitor in good condition? |
the display
would immediately show very low resistance but gradually climb to 'OL' |
the display
would immediately show very low resistance but rapidly climb to a
slightly higher value and remain there |
the display
would immediately show very low resistance and remain at this value |
the display
would immediately show 'OL' ohms and remain at this value |
|
A |
When
compared to an electronic digital voltmeter, the main disadvantage of
the Simpson 250 analog multimeter is which of the following? |
Tends to
"load" the circuit being tested. |
Has a
greater margin of error. |
Has a less
margin of error. |
Tends to
"unload" the circuit being tested. |
|
B |
As shown in
figure "A" of the digital multimeter screen shown in the illustration,
what would be the significance of the symbol indicated by "1" being
illuminated? Illustration EL-0047
" |
the meter is
subjected to a potentially unsafe voltage |
the selector
switch is selected for continuity/diode test and the secondary
function pushbutton is toggled for continuity |
the meter
test leads are placed in the wrong terminal jacks for the test being
performed |
the meter is
in range of a wireless signal |
|
B |
As shown in
figure "D" of the digital power meter shown in the illustration, what
type of single phase load is under test for power measurement?
Illustration EL-0256 |
a
resistive-capacitive load |
an
inductive-resistive load |
a purely
inductive load |
a purely
resistive load |
|
C |
In testing a
hand cranked megger prior to use, what statement is true? |
With the
test leads shorted or open, the pointer should go to zero ohms. |
With the
test leads shorted or open, the pointer should go to infinite ohms. |
With the
test leads shorted, the pointer should go to zero ohms, and with the
tests leads open, the pointer should go to infinite ohms. |
With the
test leads shorted, the pointer should go to infinite ohms, and with
the tests leads open, the pointer should go to zero ohms. |
|
D |
When a
megohmmeter is being used to test insulation resistance, current
leakage along the surface of the insulation is indicated by a very
specific megohmmeter pointer movement. What would be the
characteristic of the pointer movement under these conditions? |
continually
rising as the test voltage is applied |
dipping
towards 'zero', then rising slowly |
fluctuating
around a constant resistance reading |
kicking
slightly down scale as voltage is applied |
|
A |
When a
megohmmeter is used to test insulation, what condition causes the
gradual rise of the pointer reading as a result of continued cranking? |
the
dielectric-absorption effect of the insulation |
good
conductor resistance |
the
inductive reactance of the windings |
the leakage
of current along the surface of dirty insulation |
|
D |
In which of
the situations listed will a megohmmeter give the most accurate
readings? |
While the
machine is in operation. |
Immediately
prior to restarting the machine. |
While the
machine is discharging static electricity. |
When the
machine has been shut down and grounded for a period of 15 minutes. |
|
D |
What is the
resistance reading at "1" on the megger scale illustrated in figure
"A"? Illustration EL-0044 |
150 ohms |
150 thousand
ohms |
120 megohms |
150 megohms |
|
D |
If
overloading an electric motor becomes necessary in an emergency
situation, what should be done to prevent damage to the motor while
allowing sustained operation? |
increase the
residual magnetism value of windings to reduce eddy currents |
hold thermal
overload relays open with blocks of wood |
inject small
amounts of CO2 into the windings for cooling |
cool the
motor with portable blowers and fans |
|
C |
What should
be included in the routine periodic maintenance checks for electrical
motors? |
checking for
watertight integrity |
checking for
speed droop |
checking for
vibration |
checking for
reactive power |
|
A |
When
re-greasing the electric motor bearing as shown in figure "B" of the
illustration, what practice should be avoided? Illustration EL-0218 |
Completely
filling the bearing cavity with new grease. |
Flushing out
the old grease while running the motor with no load. |
Flushing out
the old grease with an approved solvent. |
Only
partially filling the bearing cavity with new grease. |
|
D |
When testing
insulation resistance of electric equipment and machinery, ideally
when should the insulation resistance be tested for the lowest normal
insulation values? |
every time
the brush rigging is adjusted |
every 30
days whether the machine is in use or not |
immediately
after starting up the machine |
immediately
after shutting down the machine |
|
B |
What would
be the indication of a grounded switch or cable as measured by a
megohmmeter? |
being
unsteady in the low range |
zero' |
being
unsteady in the high range |
infinity |
|
D |
As shown in
the illustrated plots of uncorrected and temperature corrected
insulation resistance readings for a particular piece of equipment, at
what point in time should the equipment have been refurbished or
replaced? Illustration EL-0120 |
2006 |
2008 |
2010 |
no
refurbishment or replacement was necessary through 2011 |
|
A |
Before any
work on electrical or electronic equipment is performed, which of the
following precautions should be carried out? |
Secure and
tag the supply circuit breaker in the open position. |
De-energize
the applicable switchboard bus. |
Bypass the
interlocks. |
Station a
man at the circuit supply switch. |
|
D |
Which of the
listed battery charging circuits is used to maintain a wet-cell,
lead-acid, storage battery in a fully charged state during long
periods of disuse? |
Normal
charging circuit |
High ampere
charging circuit |
Quick
charging circuit |
Trickle
charging circuit |
|
D |
What is the
best method of determining the state of charge of a lead acid storage
battery? |
ampere hour
capacity of the battery |
total cell
voltages |
testing of
the individual cell voltages |
specific
gravity of the electrolyte |
|
B |
Which of the
following activities occurs during the charging process of a lead-acid
storage battery? |
Hydrogen gas
is absorbed. |
The specific
gravity of the acid increases. |
Oxygen gas
is absorbed. |
Both plates
change chemically to lead sulfate. |
|
C |
Why must
caution be exercised during the charging of lead-acid storage
batteries? |
the acid
will become weaker |
both plates
are changing chemically to lead sulfate |
hydrogen gas
is being continuously liberated |
lead
peroxide in the negative plate is poisonous |
|
C |
What
statement is true concerning the actual mixing process and the
container used when mixing electrolyte for a lead-acid storage
battery? |
pour the
distilled water into the acid in a glass container |
pour the
distilled water into the acid in a zinc-plated container |
pour the
acid into distilled water in a glass container |
pour the
acid into the distilled water in a zinc-plated container |
|
A |
What
statement is true concerning the charging a 100 amp-hour lead-acid
battery? |
The initial
charging rate should be no greater than 100% of the battery amp-hour
rating. |
The source
of power for charging should be 2.0 volts per cell. |
The charging
rate should be 100 amps for one hour. |
The
temperature of the electrolyte should not be allowed to exceed 90°F. |
|
A |
Which of the
following statements concerning nickel-cadmium batteries is true? |
Nickel-Cadmium batteries can be stored for a long period of time while
still keeping a full charge. |
When mixing
the electrolyte always add water to the acid. |
When mixing
the electrolyte always add acid to the water. |
The
electrolyte of an idle Nickel-Cadmium battery must be replaced monthly
to maintain battery condition. |
|
A |
What should
you be aware of when checking the specific gravity of the battery
electrolyte with a hydrometer? |
depending on
the temperature it may be necessary to correct for temperature |
the battery
is discharged when the float is highest in the electrolyte |
a hydrometer
reading is accurate if taken immediately after water is added to the
cell |
the battery
is fully charged when the float sinks deepest into the electrolyte |
|
B |
For accuracy
purposes, which of the following devices should be used to measure the
temperature of a battery electrolyte? |
Mercury
thermometer |
Electronic
digital thermometer |
Potentiometer |
Thermocouple
pyrometer |
|
B |
Which of the
substances listed should be applied to battery terminals to help
prevent corrosion? |
Zinc
chromate |
Petroleum
jelly |
Lead
hydroxide |
Lead
peroxide |
|
A |
You are
reconnecting a three-phase induction motor to the supply line. To
prevent possible damage to the load, due to the wrong direction of
rotation, what should be done? |
check the
supply line phase sequence and motor rotation with appropriate
indicators, then connect correspondingly marked leads |
connect the
motor and then use the 'jog' button to determine the direction of
rotation |
connect the
phase indicator to the motor leads, rotate the motor by hand and then
connect to the supply voltage |
connect the
phase indicator to the supply voltage then connect the motor |
|
C |
What is a
useful instrument for checking 3-phase AC motor performance by
measuring possible unbalanced currents? |
D'Arsonval
iron-vane probe |
hand or
battery-operated megger |
clamp-on
ammeter |
vibrating-reed frequency meter |
|
C |
Suppose it
is desired to connect a dual voltage three-phase squirrel-cage
induction motor for low volts, but it is undetermined whether the
nine-lead motor is internally configured for wye or delta
configuration. Using an ohmmeter, the motor itself with leads
disconnected, and the illustration as a guide, what statement is true?
Illustration EL-0134 |
If leads
"7", "8", and "9" have continuity across each other, the motor is
"delta" configured. Without continuity, the motor is "wye" connected. |
If leads
"4", "5", and "6" have continuity across each other, the motor is
"delta" configured. Without continuity, the motor must be "wye"
connected. |
If leads
"7", "8", and "9" have continuity across each other, the motor is
"wye" configured. Without continuity, the motor is "delta" configured. |
If leads
"4", "5", and "6" have continuity across each other, the motor is
"wye" configured. Without continuity, the motor must be "delta"
connected. |
|
C |
Which of the
conditions listed will indicate the need to clean the insulation on
the windings of an electric motor? |
Excessive
vibration at normal speed. |
Sparking at
the brushes. |
Higher than
normal operating temperature. |
High megger
readings. |
|
C |
When using
the test set-up shown in figure "A" of the illustration, besides the
motor windings and the motor feeder cable, what circuit components are
actually being meggered? Illustration EL-0027 |
The power
circuit of the starter up to the load side of the overload relay
heaters |
the power
circuit of the starter up to the load side of the disconnect switch |
the power
circuit of the starter up to the load side of the main contacts |
the entire
starter, including the power and control circuits, up to the load side
of the disconnect switch |
|
A |
Large
machines undergoing a resistance insulation testing using a
megohmmeter should be discharged to remove any accumulated
electrostatic/capacitive charge stored. When should this discharge be
performed? |
prior to and
after conducting the insulation resistance check |
after
conducting the insulation resistance check only |
prior to
conducting the insulation resistance check only |
while
performing the insulation resistance check only |
|
B |
When you are
making a high potential test (megger) on the motor coils of repaired
electrical machinery to ground. What would a low resistance reading
indicate? |
a high slot
discharge factor |
bad
insulation |
high
insulation power factor |
good
insulation |
|
A |
Using the
temperature correction factor for the winding insulation temperature
graph shown in the illustration, what would be the correction factor
and the corrected temperature to 40 degrees C for a motor with a
insulation resistance of 4 megohms measured at 50 degrees C?
Illustration EL-0046 |
The
temperature correction factor is 2 and the corrected resistance is 8
megohms at 40 degrees C. |
The
temperature correction factor is 0.5 and the corrected resistance is 2
megohms at 40 degrees C. |
The
temperature correction factor is 0.5 and the corrected resistance is 8
megohms at 40 degrees C. |
The
temperature correction factor is 2 and the corrected resistance is 2
megohms at 40 degrees C. |
|
B |
Which of the
listed conditions will occur if dirt and grease are allowed to
accumulate between the commutator segments of a DC motor? |
Misalignment
of the motor shaft. |
A partial
short circuit. |
A dead short
circuit. |
Over
speeding of the motor. |
|
D |
In general,
what can cause D.C. propulsion motor brush sparking to be excessive? |
brushes
positioned in the neutral plane |
a dark
chocolate colored commutator |
a concentric
commutator |
incorrect
brush grade, pressure or position |
|
B |
What should
be used in the cleaning of a D.C. propulsion motor's commutator face? |
emery cloth |
a canvas
wiper |
abrasive
dressing stones |
sandpaper |
|
D |
How is the
seating the brushes on a DC motor commutator first accomplished? |
emery paper
for the initial cut and crocus cloth for the finishing cut |
a file for
cutting the approximate curvature followed by sandpaper for the final
fit |
course
lapping compound, followed by a medium and then a fine grade |
using fine
sandpaper on a deenergized machine between the brush and the
commutator to establish the proper curvature |
|
B |
D.C.
propulsion motor brush pressure depends on the brush grade used. In
practice with what device is the proper brush pressure established? |
manometer |
spring scale |
compound
gauge |
multimeter |
|
B |
With regard
to the maintenance of electrical generating machines with insulated
pedestal bearings, what practice should be avoided? |
touching the
bearing shell while the machine running |
painting or
allowing grease build up on the insulated area |
using a
megohm meter with the machine disassembled to determine insulation
values |
cleaning and
removing grease from the insulated area |
|
C |
Rotor-to-stator air gap readings should be periodically taken for
electrical generation equipment. What is the best tool to use to take
these measurements? |
dial
indicator |
inside
micrometer |
tapered,
long blade, feeler gage |
cloth
(non-metallic) tape measure |
|
C |
If
rotor-to-stator air gap readings for an electrical generating machine
have changed significantly from the last reading, what should be
checked? |
insulation
readings and machine cleanliness |
the prime
mover thrust bearing for wear |
the
generator bearings for wear |
the field
coil bolts for the proper torque values |
|
D |
In
performing routine maintenance of a ship's service alternator, what
should be included? |
lubricating
exciter slip rings |
megger
testing of all rectifying diodes |
changing the
pedestal bearing insulation yearly |
periodic
cleaning of the air filters or screens |
|
C |
How may
chattering of the collector/slip ring brushes on a generator be
remedied? |
lubricating
brush holders |
reinsulating
the brushes |
cleaning the
collector rings with a canvas wiper |
increasing
length of pigtail |
|
C |
Which of the
following materials is recommended for burnishing the slip rings of an
alternator after grinding or turning? |
canvas wiper |
grade 00
sandpaper |
hardwood
block |
smooth file |
|
D |
Which of the
following statements, concerning the cleaning maintenance of a
brushless generator, is correct? |
Cleaning of
windings should be performed on a periodic basis regardless of the
state of cleanliness. |
Hot soapy
water should be used to remove dust and grime from windings. |
High
pressure air should be used to blow out dust and grime from the
windings. |
Cleaning of
windings should be performed on a conditional basis using a vacuum or
using a clean, dry, lint-free rag. |
|
B |
When an
alternator is to remain idle for even a few days, what should be done? |
open the
equalizing bus disconnect switch |
energize the
space heater circuit |
insulate the
collector rings with strips of cardboard |
lift the
brushes and disconnect the pigtails |
|
A |
While
inspecting the copper commutator bars of a DC generator, you notice a
chocolate brown film covering the bars. What should be done? |
The film
should be left undisturbed. |
The film
should be removed with fine emery cloth. |
The film
should be removed with fine sandpaper. |
The film
should be removed with emery paper. |
|
C |
As the
brushes ride on the commutator of a DC generator, eventually mica
ridges will form between the bars causing sparking and chipping of the
brushes. When this happens the mica must be undercut. To what depth is
the mica undercut? |
The mica
slots are undercut to a depth 1mm below the surface of the commutator
bars. |
The mica
slots are undercut to a depth approximately twice the width of the
slot. |
The mica
slots are undercut to a depth approximately equal to the width of the
slot. |
The mica
slots are undercut. but the actual depth is unimportant. |
|
C |
Referring to
the illustration of possible brush holder mounting configurations,
which figure is the correct method of configuring the brush holders on
a DC generator? Illustration EL-0057 |
A |
B |
C |
D |
|
D |
Incorrect
brush pressure can result in accelerated brush wear on a DC generator.
What statement concerning brush pressure is true? |
The wear
rate on brushes is proportional to the brush pressure; in other words,
the greater the brush pressure the greater the rate of brush wear. |
The wear
rate on brushes is inversely proportional to the brush pressure; in
other words, the lower the brush pressure the greater the rate of
brush wear. |
There is an
optimal pressure range that results in minimal brush wear. Brush
pressures above the optimal range cause excessive electrical wear, and
brush pressures below the optimal range cause excessive mechanical
wear. |
There is an
optimal pressure range that results in minimal brush wear. Brush
pressures above the optimal range cause excessive mechanical wear, and
brush pressures below the optimal range cause excessive electrical
wear. |
|
D |
If a DC
generator was disassembled during overhaul, it is important that the
brush holder rigging be installed in the neutral plane. On larger
machines, if the brush rigging and end bells are not match-marked,
what is the correct procedure for determining the neutral setting
using factory marks? |
With the
marked armature slots positioned directly between the interpoles and
the main field poles, the brushing rigging should be adjusted and
clamped so that the brushes are positioned directly over the marked
armature bars. |
With the
marked armature slots positioned directly under the center of the
compensating windings, the brushing rigging should be adjusted and
clamped so that the brushes are positioned directly over the marked
armature bars. |
With the
marked armature slots positioned directly under the center of the main
field poles, the brushing rigging should be adjusted and clamped so
that the brushes are positioned directly over the marked armature
bars. |
With the
marked armature slots positioned directly under the center of the
interpoles, the brushing rigging should be adjusted and clamped so
that the brushes are positioned directly over the marked armature
bars. |
|
C |
The current
at which a magnetic-type overload relay tends to trip may be decreased
by raising the plunger further into the magnetic circuit of the relay.
What effect does this action have? |
increases
magnetic pull on the plunger and requires more current to trip the
relay |
reduces
magnetic pull on the plunger and requires less current to trip the
relay |
increases
magnetic pull on the plunger and requires less current to trip the
relay |
reduces
magnetic pull on the plunger and requires more current to trip the
relay |
|
D |
Which of the
following methods should be used to dress the face of silver-plated
contacts? |
Knurling
with a knurling tool |
Filing with
a mill file |
Burnishing
with a burnishing tool |
Sanding with
0000 sandpaper |
|
C |
High
pressure compressed air should not be used to clean electric motors or
controller equipment. Why not? |
the air
blast dries out insulation quickly |
a mask and
respirator would be required |
it may embed
metallic particles into coil insulation |
the
surrounding area may need additional cleaning |
|
D |
Why are
electric strip heaters used in motor controllers? |
keep the
components at their design ambient temperature |
minimize
resistance in internal circuits |
prevent
freezing of movable contacts |
prevent
condensation of moisture |
|
B |
Before
working on an electric cargo winch master switch or controller, what
should be done? |
heat the
switch box to remove any moisture |
open the
circuit breaker in the power supply and tag-out |
drain
condensate from the box |
spray the
gasket surface with a solvent |
|
A |
Which of the
listed pairs of materials make the best insulators? |
paper and
mica |
dry air and
a vacuum |
salt water
and moist earth |
doped
silicon and germanium |
|
D |
What device
can be used to check the calibration of a circuit breaker? |
500 volt
megohmmeter |
standard
digital multimeter |
500 volt
megohmmeter |
portable low voltage high current testing unit
(e) clamp-on voltmeter |
|
D |
As shown in
figure "A" of the illustration, what phenomenon is illustrated with
respect to electrical cables and ground? Illustration EL-0126 |
associative
capacitance |
associative
inductance |
distributive
inductance |
distributive
capacitance |
|
B |
When a
megohmmeter is used to test insulation, what condition causes the
gradual rise of the pointer reading as a result of continued cranking? |
the leakage
of current along the surface of dirty insulation |
the
dielectric-absorption effect of the insulation |
good
conductor resistance |
the
inductive reactance of the windings |
|
C |
When a
fluorescent lamp has reached the end of its useful life, it should be
replaced immediately. If not, what condition could the resultant
flashing cause? |
tripping of
the lamp's circuit breaker |
exploding of
the lamp, causing glass to fly in all directions |
damaging the
lamps starter and ballast circuit |
short
circuiting of adjacent lighting circuits |
|
D |
As part of a
routine maintenance program for deck machinery motor controllers, what
should be done? |
check drum
switch contact pressure every three months |
remove motor
covers and ventilate as weather permits |
remove
covers exposed to the weather and drain water each week |
inspect
electrical wiring for evidence of corrosion or discoloration at
connections |
|
A |
If deck
machinery is expected to be idle for an extended period of time, what
should be done? |
energize
space heaters to prevent the condensation of moisture |
have
electrical safety gloves available in case of electrical shock before
running |
perform a
'high pot' test to determine the condition of the insulation |
water wash
the motor and controller to remove any salt that may interfere with
smooth operation |
|
B |
If a
spring-set electric solenoid-released brake on a winch fails to hold a
load properly when the solenoid is de-energized, what must be done? |
The solenoid
coil must be replaced as it is faulty. |
The brakes
linings must be checked for wear and adjusted or replaced accordingly. |
The spring
must be replaced as it has lost its compression force. |
The brake
drum must be checked for wear and replaced as needed. |
|
D |
An AC winch
hoist controller such as shown in the illustration has welded contacts
on the hoist contactor, and the contacts must be replaced. Before
replacing the contacts, the cause for the welding of the contacts must
be determined. What statement represents possible causes? (EL0102) |
The welding
of contacts may be caused by low applied voltage to the operating coil
(less than 85% of rated voltage) or by excessively strong springs. |
The welding
of contacts may be caused by excessively applied voltage to the
operating coil (more than 110% of rated voltage) or by excessively
strong springs. |
The welding
of contacts may be caused by excessively applied voltage to the
operating coil (more than 110% of rated voltage) or by weak springs. |
The welding
of contacts may be caused by low applied voltage to the operating coil
(less than 85% of rated voltage) or by weak springs. |
|
C |
An AC winch
hoist controller such as shown in the illustration has a burned out
hoist contactor coil, and the coil must be replaced. Before replacing
the coil, the cause for the burn-out must be determined. What
statement represents possible causes? Illustration EL-0102 |
The coil
burnout may be caused by insufficient voltage applied to the coil
(below 85% of rated voltage); however, excessive voltage applied to
the coil (above 110% of rated voltage) will not cause a burnout. |
The coil
burnout may be caused by excessive voltage applied to the coil (above
110% of rated voltage); however, insufficient voltage applied to the
coil (below 85% of rated voltage) will not cause a burnout. |
The coil
burnout may occur with a normal voltage applied to the coil (between
85% and 110% of rated voltage) if accumulated dirt prevents proper
seating of the armature to the magnet. |
The coil
burnout may occur with a normal voltage applied to the coil (between
85% and 110% of rated voltage) if the armature is allowed to seat
against the magnet with no air gap. |
|
A |
Why are
space heaters provided on larger generators? |
maintain
rotor and stator winding temperatures above the dew point to prevent
the formation of condensation |
prevent
condensation in the lube oil |
prevent
electrolysis due to condensation in the bearings |
keep the
machine at ambient temperature of the machinery space |
|
C |
Which of the
following statements is true concerning all rotating-field three-phase
alternators? |
Each has
three separate but identical, interconnected stator windings (one for
each phase) acted on by three separate but identical, interconnected
systems of rotating magnets (one for each phase). |
Each has one
stator winding acted on by three separate but identical,
interconnected systems of rotating magnets (one for each phase). |
Each has
three separate but identical, interconnected stator windings (one for
each phase) acted on by one system of rotating magnets. |
Each has one
stator winding acted on by one system of rotating magnets. |
|
B |
What is the
most common type of AC service generator found aboard ship in terms of
armature and field types? |
stationary
electromagnetic field, oscillatory armature type |
stationary
armature, rotating electromagnetic field type |
stationary
armature, oscillatory electromagnet field type |
stationary
electromagnetic field, rotating armature type |
|
C |
By what
means is voltage and current generated by modern revolving field AC
generators brought out from the alternator enclosure to the connected
switch board? |
brushes on
collector rings |
brushes on
slip rings |
direct
connections from the stator |
brushes on a
commutator |
|
D |
Of the
listed factors that influence the amount of RMS voltage induced in the
windings of an AC generator operating at a constant 60 Hz frequency,
which factor is variable during generator operation? |
the number
of armature coil turns in series per winding |
the number
of field coil turns in series per winding |
the
rotational speed at which the magnetic field passes across the stator
winding |
the strength
of the rotating magnetic field |
|
C |
Compared to
conventional alternators, brushless alternators are designed to
operate without the use of what? |
voltage
regulators |
rectifiers |
slip rings
and commutators |
exciters |
|
C |
In a
conventional AC generator utilizing brushes, direct current from the
exciter output is passed through the windings of the main field rotor
by what means? |
by means of
a commutator |
by means of
rotating bar magnet |
by means of
slip rings |
to minimize
the danger of arc over |
|
D |
As shown in
the illustration, which brush holder would be appropriate to use in a
bidirectional motor? Illustration EL-0029 |
trailing
mount only |
both leading
and trailing mount |
leading
mount only |
radial mount |
|
A |
A DC
generator which is used to supply direct current in order to provide
magnetizing current to an AC generator field is commonly known as
what? |
exciter |
rotor |
stator |
armature |
|
C |
By what
means is a diesel driven emergency generator prevented from being
paralleled with the ship's service generators? |
the reverse
current relay |
the
synchronizing oscilloscope |
an
electrical interlock system |
an automatic
paralleling trip switch |
|
A |
What does
the amount of voltage induced in the stator windings of a modern AC
generator mainly dependent upon? |
the strength
of the rotating magnetic field |
the number
of field poles energized |
the
cross-sectional area of the stator windings |
the number
of brushes associated with the commutator |
|
B |
When would
be the safest time to close the ship's main switchboard "shore power"
circuit breaker? |
at any time
in a shipyard |
when the
ship's generators have been disconnected from the main bus |
only after
the ship's generators have been directly paralleled to those on shore |
if a quick
disconnect coupling is used |
|
D |
When shore
power is being connected to a ship in dry dock, what must be ensured,
assuming that the ship's generators are rated at 450 VAC, 60Hz with a
total capacity of 5000 kW? |
exactly 60
Hz must be supplied from shore, as no tolerance is permitted |
shore power
must be capable of delivering a total of 5000 kW |
exactly 450
volts must be supplied from shore, as no tolerance is permitted |
shore power
phase sequence must agree with that of the ship |
|
A |
What is the
main purpose of an electric space heater installed in a large AC
generator? |
prevent
moisture from condensing in the windings during shutdown |
prevent
acidic pitting of the slip rings |
keep the
lube oil warm for quick starting |
prevent the
windings from becoming brittle |
|
D |
In which
figure shown in the illustration will the highest voltage be induced?
Illustration EL-0028 |
figure "A"
only |
figure "B"
only |
both figures
"A" and "C" |
both figures
"B" and "D" |
|
C |
How are AC
and DC generators are similar? |
They both
rectify the voltage before delivery. |
They both
supply three-phase power. |
They both
internally generate alternating current voltages. |
They both
operate at 60 cycles. |
|
A |
With what
device is the RPM of an AC generator indirectly measured on a
switchboard when operating singly (no other generator connected to the
bus)? |
frequency
meter |
voltmeter |
synchroscope |
synchronizing lamps |
|
C |
Upon failure
of the ships normal electrical power supply, by means of what device
does the emergency generator supply power to the emergency
switchboard, but not the main switchboard? |
power
failure alarm bus |
main
lighting transformer |
automatic
bus transfer switch |
main
switchboard bus |
|
C |
Which of the
methods listed below is used to provide the rotational torque to cause
an AC generator to turn? |
Providing
current to the field from an external source. |
Residual
magnetism remaining in the armature. |
Starting of
the prime mover. |
Residual
magnetism remaining in the field. |
|
D |
Prior to
manually starting an AC generator prime mover and paralleling in the
manual control mode, what should be the position of the voltage
regulator selector switch? |
transfer
position |
automatic
position |
bus neutral
position |
manual
position |
|
C |
Regarding an
AC generator connected to the main electrical bus; as the electric
load and power factor vary, a corresponding change is reflected in the
generator armature reaction. How are these changes in armature
reaction compensated for? |
phase-balance relay |
governor
speed droop setting |
voltage
regulator |
balance coil |
|
A |
How is the
power factor of an AC generator operating singularly determined? |
the
connected load |
the prime
mover speed |
the
generator's rated voltage |
the ground
current |
|
D |
When
securing an AC generator, what should be your FIRST action in
accomplishing the procedural steps? |
decrease the
field excitation to minimum |
open the
generator circuit breaker |
switch the
voltage regulator to 'manual' |
reduce the
load on the unit |
|
C |
The governor
control switch of an alternator is moved to the 'raise' position. What
will be the effect of this action? |
raise the
percentage of speed droop |
lower the
no-load speed setting of the governor |
raise the
no-load speed setting of the governor |
lower the
percentage of speed droop |
|
C |
How will the
value of the output frequency change if the load is removed from a
turbo generator having a governor speed droop setting of 3%? |
It will
decrease by approximately 3%. |
It will
remain unchanged. |
It will
increase. |
It will
become variable. |
|
A |
How are the
number of cycles per second developed by the alternator aboard your
vessel determined? |
the speed of
the engine driving the alternator |
the
resistance applied to the field rheostat |
the
adjustments made to the voltage regulator |
the
synchronous speed of induction |
|
A |
How is the
frequency of an alternator at a given RPM determined? |
by the
number of magnetic poles |
by the
number of turns of wire in the armature coil |
by the
strength of the magnets used |
by the
output voltage |
|
B |
What is the
most practical way to control the voltage output of an AC generator? |
varying the
speed of the rotating field |
varying the
strength of the rotating magnetic field |
varying the
number of windings |
varying the
power factor of the load |
|
D |
A main
switchboard synchronizing panel is fitted with two synchronizing lamps
and a synchroscope. When paralleling, if the synchroscope pointer is
at the noon position and one synchronizing light is bright while the
other remains dark, what does this indicate? |
the incoming
generator voltage is too low |
the
generator breaker may be closed |
the
generators are in phase sequence but one lamp is burned out |
the
generators are out of phase sequence and one lamp is burned out |
|
D |
You are
paralleling two alternators. The synchronizing lamps grow dim and are
totally darkened as the synchroscope pointer approaches the 0°
position. What does this indicate? |
the
alternator voltages are 180° apart |
the incoming
alternator is running too slowly |
the
synchroscope is defective or broken |
the circuit
breaker can be closed |
|
B |
If the
excitation of an alternator operating in parallel is decreased below
normal and the other above normal, what will be the result on the
alternator with the excitation decreased below normal? |
ampere load
will be greatly increased |
power factor
will change in the leading direction |
kilowatt
load will be greatly decreased |
power factor
will change in the lagging direction |
|
A |
What device
is used so that the kilowatt load sharing can be adjusted on
paralleled generators? |
governor
control |
hand
tachometer |
automatic
voltage regulators |
field
rheostat |
|
A |
Two AC
generators of the same capacity are operating in parallel. One with a
zero speed droop setting and the other with a 5% speed droop. If its
capacity is not exceeded, what will be the characteristic of the unit
whose governor has the zero speed droop setting? |
it will
maintain the frequency of the system |
it will have
poor sensitivity characteristics |
it will have
poor power response |
it will
assume the smaller share of the load |
|
C |
When
paralleling two alternators using three synchronizing lamps, the
flickering of all three lamps becomes progressively slower and slower.
What does this mean? |
The phase
rotation of the incoming alternators is opposite to that of the bus. |
The
frequency of the incoming alternator is significantly less than that
of the bus. |
The
frequency of the incoming generator is approaching that of the bus. |
The terminal
voltage of the incoming alternator is approaching that of the bus. |
|
C |
Which of the
following statements is true concerning the operation of two
alternators in parallel? |
Both
alternator governors must be set with the same amount of speed droop. |
The number
of field poles must be the same on each alternator. |
The cycles
per second of each alternator are the same. |
The load
must always be divided equally between alternators. |
|
D |
You are
attempting to parallel two AC generators and the synchroscope pointer
is revolving in the fast direction. What is the frequency of the
oncoming generator relative to the bus frequency? |
the same as
the bus frequency and the circuit breaker may be closed at any pointer
position |
lower than
the bus frequency |
the same as
the bus frequency but out of phase with it |
higher than
the bus frequency |
|
D |
Attempting
to parallel an AC generator which is out of phase with the bus will
result in which of the following conditions? |
The power
factor will be unitized |
The
synchronizing lamps will burn out. |
The kVA will
decrease. |
The
alternator breaker should trip. |
|
A |
What devices
maintains equal power factors on paralleled AC generators
automatically? |
voltage
regulators |
reverse
current relays |
reverse
power relays |
governor
speed control switches |
|
C |
With regard
to the maintenance of electrical generating machines with insulated
pedestal bearings, what practice should be avoided? |
cleaning and
removing grease from the insulated area |
using a
megohm meter with the machine disassembled to determine insulation
values |
painting or
allowing grease build up on the insulated area |
touching the
bearing shell while the machine running |
|
B |
Rotor-to-stator air gap readings should be periodically taken for
electrical generation equipment. What is the best tool to use to take
these measurements? |
cloth
(non-metallic) tape measure |
tapered,
long blade, feeler gage |
dial
indicator |
inside
micrometer |
|
B |
If
rotor-to-stator air gap readings for an electrical generating machine
have changed significantly from the last reading, what should be
checked? |
the field
coil bolts for the proper torque values |
the
generator bearings for wear |
the prime
mover thrust bearing for wear |
insulation
readings and machine cleanliness |
|
C |
In
performing routine maintenance of a ship's service alternator, what
should be included? |
lubricating
exciter slip rings |
megger
testing of all rectifying diodes |
periodic
cleaning of the air filters or screens |
changing the
pedestal bearing insulation yearly |
|
D |
Which of the
following statements, concerning the cleaning maintenance of a
brushless generator, is correct? |
High
pressure air should be used to blow out dust and grime from the
windings. |
Hot soapy
water should be used to remove dust and grime from windings. |
Cleaning of
windings should be performed on a periodic basis regardless of the
state of cleanliness. |
Cleaning of
windings should be performed on a conditional basis using a vacuum or
using a clean, dry, lint-free rag. |
|
D |
How may
chattering of the collector/slip ring brushes on a generator be
remedied? |
increasing
length of pigtail |
reinsulating
the brushes |
lubricating
brush holders |
cleaning the
collector rings with a canvas wiper |
|
D |
Which of the
following materials is recommended for burnishing the slip rings of an
alternator after grinding or turning? |
canvas wiper |
smooth file |
grade 00
sandpaper |
hardwood
block |
|
D |
When an
alternator is to remain idle for even a few days, what should be done? |
lift the
brushes and disconnect the pigtails |
open the
equalizing bus disconnect switch |
insulate the
collector rings with strips of cardboard |
energize the
space heater circuit |
|
D |
How can the
loss of residual magnetism in an alternator or generator be corrected? |
running the
generator at normal speed with the field rheostat fully
counterclockwise |
allowing the
generator to run at 10% of normal speed for 5 minutes |
running the
rotor in the opposite direction for 5 minutes |
using a
storage battery or battery charger to 'flash' the field |
|
C |
An open
occurring within the field rheostat of an AC generator can be detected
by short circuiting its terminals and making specific observations.
What should be checked for? |
negative
deflection of the wattmeter pointer |
positive
deflection of the wattmeter pointer |
buildup of
alternator voltage |
low, but
constant alternator voltage |
|
B |
What may be
the cause of an AC generator to fail to produce a voltage? |
high mica
segments on the stator bus bar |
an open in
the rotor field circuit |
short
circuit in the stator coils |
a tripped
bus circuit breaker |
|
D |
If a
shipboard AC generator experiences a failure to produce a voltage,
what may be the cause? |
a rotating
slip ring |
the brushes
shifting out of the neutral plane |
excessive
locked-rotor current |
an open in
the rotor field circuit |
|
A |
Which of the
following statements about a three-phase wye connected alternator is
correct? |
The line
voltage is 1.73 times the phase voltage. |
The phase
current is 1.73 times the line current. |
The phase
voltage is 1.73 times the line voltage. |
The line
current is 1.73 times the phase current. |
|
B |
Of the
listed factors that influence the amount of RMS voltage induced in the
windings of an AC generator operating at a constant 60 Hz frequency,
which factor is variable during generator operation? |
the number
of armature coil turns in series per winding |
the strength
of the rotating magnetic field |
the
rotational speed at which the magnetic field passes across the stator
winding |
the number
of field coil turns in series per winding |
|
A |
If the
driving torque, such as that produced by a diesel engine, creates
pulsations when coupled with a synchronous generator operating in
parallel, the generator rotor may be periodically pulled ahead or
behind its normal position as it rotates. How can this condition
called hunting be reduced? |
by the use
of amortisseur windings |
by
decreasing governor speed droop |
by direct
coupling |
by
increasing governor speed droop |
|
D |
How are AC
and DC generators are similar? |
They both
internally produce three-phase power. |
They both
rectify the current before delivery. |
They are
both constructed at the same physical size for the same kilowatt
rating |
They both
internally generate alternating current voltages. |
|
B |
A DC
generator which is used to supply direct current in order to provide
magnetizing current to an AC generator field is commonly known as
what? |
armature |
exciter |
stator |
rotor |
|
B |
From the
information given in the illustration, what would be the maximum
output amperage available from the emergency generator if it operated
with a power factor of 0.9? Illustration EL-0106 |
937 amps |
669 amps |
541 amps |
1156 amps |
|
B |
Which of the
methods listed below is used to provide the rotational torque to cause
an AC generator to turn? |
Residual
magnetism remaining in the field. |
Starting of
the prime mover. |
Providing
current to the field from an external source. |
Residual
magnetism remaining in the armature. |
|
A |
From the
information given in the illustration, which of the following
statements is correct? Illustration EL-0106 |
It is
normally the case where the main-emergency bus-tie circuit breaker and
any on-line ship's service generator circuit breakers be
simultaneously closed. |
It is
possible for the main-emergency bus-tie circuit breaker and the
emergency generator circuit breaker to be simultaneously closed. |
The
emergency generator is capable of being connected directly to the main
480 VAC bus. |
Shore power,
in port, is only capable of feeding emergency loads. |
|
C |
Two AC
generators are operating in parallel and both are equipped with
automatic voltage regulators. While standing watch, one generator is
noted as having a greater lagging kvar value. In order to equalize the
kvars between the generators manually, what should be done? |
increase the
voltage of the generator with the largest kvar while decreasing the
other generator voltage |
increase the
speed of the generator with the largest kvar while decreasing the
other generator speed |
decrease the
voltage of the generator with the largest kvar while increasing the
other generator voltage |
decrease the
speed of the generator with the largest kvar while increasing the
other generator speed |
|
B |
When
paralleling two alternators the synchronizing lamps grow dim and are
totally darkened as the synchroscope pointer approaches the 0°
position. What does this indicate? |
the
alternator voltages are 180° apart |
the incoming
alternator is in synchronism with the bus |
the incoming
alternator is running too fast |
the
synchroscope pointer is defective or broken |
|
A |
While
paralleling two (2) AC generators using synchronizing lamps only, when
will both lamps will go dark? |
when the
generators are in synchronism |
when the
generators are running at the same speed |
when the
generators are out of synchronism |
when the
generators are running at different speeds |
|
A |
Diesel
generators #1 and #2 are operating in parallel at near full load
capacity. Diesel generator #1 suddenly trips out mechanically due to
low lube oil pressure. The reverse power relay functions properly and
trips generator #1 electrically off the board. Which of the following
actions should you carry out FIRST? |
Strip the
board of all nonvital circuits. |
Secure
alarms, reset reverse power relay, and restart #1 engine. |
Ascertain
cause of the low lube oil pressure. |
Start the
emergency generator. |
|
C |
When shore
power is being connected to a ship in dry dock, what must be ensured,
assuming that the ship's generators are rated at 450 VAC, 60Hz with a
total capacity of 5000 kW? |
shore power
must be capable of delivering a total of 5000 kW |
exactly 60
Hz must be supplied from shore, as no tolerance is permitted |
shore power
phase sequence must agree with that of the ship |
exactly 450
volts must be supplied from shore, as no tolerance is permitted |
|
D |
Upon failure
of the normal power supply, by what means is the emergency generator
placed on the line and connected to the emergency bus? |
bus tie
feeder |
line
connection feeder |
power
failure alarm bus |
automatic
bus transfer device |
|
B |
By what
means is an AC generator prevented from becoming motorized? |
over speed
trip |
reverse
power relay |
governor
controls |
back
pressure trip |
|
B |
How will the
value of the output frequency change if the load is removed from a
turbo generator having a governor speed droop setting of 3%? |
It will
become variable. |
It will
increase. |
It will
decrease by approximately 3%. |
It will
remain unchanged. |
|
B |
How are the
field windings of a DC shunt generator connected? |
in series
with the series windings |
in parallel
with the armature windings |
in series
with the armature windings |
in parallel
with the field rheostat |
|
C |
What is the
purpose of the commutator and brushes on a DC generator? |
provide a
sliding contact method to excite the field |
transfer
generated direct current voltage from the armature to the line |
convert the
alternating current voltage generated within the armature to a direct
current voltage |
reduce
sparking between the armature and the carbon brushes |
|
C |
Why are
armature cores in a DC generator made of laminated steel sheets? |
allow for
easy assembly |
increase the
hysteresis effect |
reduce eddy
current losses |
fit the
curvature of the frame |
|
B |
As shown in
the illustration of a DC machine which is configured as a generator,
what is the polarity of the interpoles as compared to the main field
poles? Illustration EL-0052 |
in the
direction of rotation, the following interpole should have the same
polarity as the preceding main pole |
in the
direction of rotation, the preceding interpole should have the same
polarity as the following main pole |
the
polarities of the interpoles 180 degrees opposite one another should
be the same, the actual polarities compared to that of the main poles
does not matter |
in the
direction of rotation, the preceding interpole should have the
opposite polarity as the following main pole |
|
C |
In referring
to the illustration of the elementary DC generator, what statement is
true? Illustration EL-0028 |
In a
complete revolution of the armature, the current flow direction within
the armature winding does not reverse, and the current flow direction
in the external load also does not reverse. |
In a
complete revolution of the armature, the current flow direction within
the armature winding does not reverse, whereas the current flow
direction in the external load does reverse. |
In a
complete revolution of the armature, the current flow direction within
the armature winding does reverse, whereas the current flow direction
in the external load does not reverse. |
In a
complete revolution of the armature, the current flow direction within
the armature winding does reverse, and the current flow direction in
the external load also does reverse. |
|
D |
In referring
to the illustration of the Ward-Leonard drive system, what type of DC
generator is used? Illustration EL-0153 |
Self-excited
shunt wound generator. |
Permanent
magnet generator. |
Self-excited
series wound generator. |
Separately
excited generator. |
|
A |
What two
factors determine the magnitude of the generated voltage of a DC
generator? |
The
rotational speed of the armature and the magnetic strength of the
field flux. |
The armature
current draw and the magnetic strength of the field flux. |
The
rotational speed of the field and the magnetic strength of the
armature flux. |
The
rotational speed of the armature and the armature current draw. |
|
B |
For the
purposes of generating a DC voltage, which of the following factors is
subject to vary for a particular generator installation while in
operation? |
The number
of field poles. |
The magnetic
strength of the field flux. |
The
arrangement of the armature windings. |
The number
of armature coils. |
|
D |
What
statement is true concerning the use of commutating poles (also known
as interpoles) in DC generators? |
These large
poles are placed in the magnetic neutral plane between the main field
poles and are designed to eliminate or reduce sparking caused by
inductance of the field coils. |
These
windings are wound on the main field poles and are designed to
eliminate or reduce sparking caused by inductance of the field coils. |
These
windings are wound on the main field poles and are designed to
eliminate or reduce sparking caused by inductance of the armature
coils. |
These narrow
poles are placed in the magnetic neutral plane between the main field
poles and are designed to eliminate or reduce sparking caused by
inductance of the armature coils. |
|
B |
What
statement is true concerning the use of compensating windings in DC
generators?
o |
These
windings are wound on the main field pole pieces and are designed to
eliminate or reduce sparking caused by inductance of the armature
coils. |
These
windings are wound on the main field pole pieces and are designed to
counteract armature reaction associated with heavy loads and minimize
field distortion. |
These narrow
poles are placed in the magnetic neutral plane between the main field
poles and are designed to eliminate or reduce sparking caused by
inductance of the armature coils. |
These narrow
poles are placed in the magnetic neutral plane between the main field
poles and are designed to counteract armature reaction associated with
heavy loads and minimize field distortion. |
|
B |
What is the
purpose of the series field used in a stabilized shunt DC generator? |
The series
field eliminates the need for commutating poles (also known as
interpoles). |
The series
field improves inherent voltage regulation beyond that of a shunt
wound generator. |
The series
field improves inherent speed regulation beyond that of a shunt wound
generator. |
The series
field eliminates the need for compensating windings. |
|
B |
With what
device is the simplest method of controlling the terminal voltage of
compound-wound DC generator? |
carbon pile
regulator in series with the load |
hand-operated field rheostat connected in series with the shunt field
circuit |
balance coil
diverting neutral current through the shunt field |
separate
exciter in a series with the shunt field |
|
B |
Prior to
closing the circuit breaker when paralleling two DC generators, what
must you be certain of? |
current from
the incoming machine is the same as the bus current |
voltage of
the incoming machine is at or slightly above the bus voltage |
synchroscope
needle is revolving slowly in the 'fast' direction |
frequency of
the incoming machine is slightly higher than the bus frequency |
|
D |
Which of the
methods listed is used to maintain equal load sharing between two
compound wound DC generators operating in parallel? |
The shunt
field rheostats are interconnected. |
The shunt
fields are interconnected. |
The series
fields of both generators are connected in series. |
The series
fields of both generators are connected in parallel. |
|
A |
By what
means is a DC generator prevented from becoming motorized if
paralleling is accomplished without an equalizer? |
reverse
current relay |
over speed
trip |
back
pressure trip |
governor
controls |
|
A |
For the
purposes of high voltage marine practice, what is the threshold
voltage where all voltages below this value are considered low
voltage? |
1.0 kV |
3.3 kV |
6.6 kV |
11 kV |
|
C |
What is a
disadvantage to the use of high voltage systems onboard ship? |
Reduced
overall size of electrical power equipment |
Less current
draw than with low voltage systems |
Necessary
adherence to stringent safety procedures |
Reduced
overall weight of electrical power equipment |
|
A |
What is the
most common and reliable type of circuit breaker used for high voltage
practice aboard ship? |
vacuum-break |
gas-break |
oil-break |
air-break |
|
D |
Some
shipboard high voltage systems have the neutral point of the
generators bonded to the ship's hull with a neutral grounding
resistor. What is the purpose of this resistor? |
To
completely eliminate ground fault current |
To maximize
the magnitude of the ground fault current |
To prevent
nuisance ground fault trips |
To minimize
the magnitude of the ground fault current |
|
D |
Suppose it
is desired to determine the integrity of the insulation of a 4160 VAC
motor. What type of insulation resistance tester (megger) would be
suitable? |
500 V megger |
1000 V
megger |
2500 V
megger |
5000 V
megger |
|
D |
Before work
may safely commence on a high voltage system, what must first be done
after disconnection and isolation? |
The circuit
must be grounded first, then tested and proved dead with a live-line
tester. |
The circuit
must be grounded first, then tested and proved dead with an off-line
tester. |
The circuit
must be tested and proved dead first with an off-line tester, then
grounded. |
The circuit
must be tested and proved dead first with a live-line tester, then
grounded. |
|
B |
In order for
a live-line tester to be used to test and prove dead a high voltage
circuit, what must be done to verify the ability of the tester to
detect a voltage?
o |
The
live-line tester need not be checked prior to testing the circuit to
be worked upon as long as it has not been declared inoperative. |
The
live-line tester should be checked by connecting to a known high
voltage source before and after the circuit to be worked upon is
tested. |
The
live-line tester should be checked by connecting to a known high
voltage source only before testing the circuit to be worked upon. |
The
live-line tester should be checked by connecting to a known high
voltage source only after testing the circuit to be worked upon. |
|
C |
In addition
to high voltage circuit grounding with ground-connecting switching
devices, for additional operator safety and confidence, portable
grounding straps may be used. What is the proper procedure for
connecting these portable grounding straps? |
The common
to hull ground connection and the phase connections to common can be
made in any sequence. |
The common
to hull ground connection and the phase connections to common should
all be made simultaneously. |
Connect the
common connection to hull ground first, then connect the phase
connections to common. |
Connect the
phase connections to common first, then connect the common connection
to hull ground. |
|
C |
When
completing repairs on a high voltage circuit where portable grounding
straps were used for increased operator safety and confidence, what is
the proper procedure for disconnecting these grounding straps? |
Disconnect
the common connection to hull ground first, then disconnect the phase
connections to common. |
The common
to hull ground and the phase connections to common should all be
disconnected simultaneously. |
Disconnect
the phase connections to common first, then disconnect the common
connection to hull ground. |
The common
to hull ground connection and the phase connections to common can all
be disconnected in any sequence. |
|
A |
For a motor
rated at 3.3 kV, what would be a minimum accepted insulation
resistance to hull ground as tested by an appropriate megger
(insulation tester)? |
4.3 megohms |
2.3 megohms |
3.3 megohms |
6.6 megohms |
|
A |
What is the
most common and reliable type of circuit breaker used for high voltage
practice aboard ship? |
vacuum-break |
gas-break |
oil-break |
air-break |
|
B |
Some
shipboard high voltage systems have the neutral point of the
generators bonded to the ship's hull with a neutral grounding
resistor? What is the purpose of this resistor? |
To prevent
nuisance ground fault trips |
To minimize
the magnitude of the ground fault current |
To
completely eliminate ground fault current |
To maximize
the magnitude of the ground fault current |
|
D |
Suppose it
is desired to determine the integrity of the insulation of a 4160 VAC
motor. What type of insulation resistance tester (megger) would be
suitable? |
500 V megger |
1000 V
megger |
2500 V
megger |
5000 V
megger |
|
C |
Before work
may safely commence on a high voltage system, what must first be done
after disconnection and isolation? |
The circuit
must be grounded first, then tested and proved dead with an off-line
tester. |
The circuit
must be grounded first, then tested and proved dead with a live-line
tester. |
The circuit
must be tested and proved dead first with a live-line tester, then
grounded. |
The circuit
must be tested and proved dead first with an off-line tester, then
grounded. |
|
C |
In order for
a live-line tester to be used to test and prove dead a high voltage
circuit, what must be done to verify the ability of the tester to
detect a voltage? |
The
live-line tester should be checked by connecting to a known high
voltage source only before testing the circuit to be worked upon. |
The
live-line tester need not be checked prior to testing the circuit to
be worked upon as long as it has not been declared inoperative. |
The
live-line tester should be checked by connecting to a known high
voltage source before and after the circuit to be worked upon is
tested. |
The
live-line tester should be checked by connecting to a known high
voltage source only after testing the circuit to be worked upon. |
|
A |
In addition
to high voltage circuit grounding with ground-connecting switching
devices, for additional operator safety and confidence, portable
grounding straps may be used. What is the proper procedure for
connecting these portable grounding straps? |
Connect the
common connection to hull ground first, then connect the phase
connections to common. |
The common
to hull ground connection and the phase connections to common can be
made in any sequence. |
The common
to hull ground connection and the phase connections to common should
all be made simultaneously. |
Connect the
phase connections to common first, then connect the common connection
to hull ground. |
|
B |
When
completing repairs on a high voltage circuit where portable grounding
straps were used for increased operator safety and confidence, what is
the proper procedure for disconnecting these grounding straps?
o |
The common
to hull ground connection and the phase connections to common can all
be disconnected in any sequence. |
Disconnect
the phase connections to common first, then disconnect the common
connection to hull ground. |
The common
to hull ground and the phase connections to common should all be
disconnected simultaneously. |
Disconnect
the common connection to hull ground first, then disconnect the phase
connections to common. |
|
C |
For a motor
rated at 3.3 kV, what would be a minimum accepted insulation
resistance to hull ground as tested by an appropriate megger
(insulation tester)? |
2.3 megohms |
3.3 megohms |
4.3 megohms |
6.6 megohms |
|
C |
When an high
voltage system insulation test value is suspect or recorded during an
annual survey, a polarization index test is performed. What is the
polarization index? |
The
polarization index is the ratio of the insulation resistance taken at
one minute to the insulation resistance taken at ten minutes. |
The
polarization index is the ratio of the insulation resistance taken at
thirty minutes to the insulation resistance taken at one minute. |
The
polarization index is the ratio of the insulation resistance taken at
ten minutes to the insulation resistance taken at one minute. |
The
polarization index is the insulation resistance taken at ten minutes. |
|
B |
What is the
item referred to as a pigtail on a DC motor brush rigging? |
brush holder |
uninsulated
wire |
flexible
spring adjuster |
feather
spring |
|
C |
What is the
function of the interpoles installed in DC motors? |
To provide
greater torque by strengthening the main field. |
To limit the
production of counter-electromotive force. |
To provide
sparkless commutation without having to shift the brushes. |
To limit the
starting surge current. |
|
D |
What is the
function of the commutator associated with a DC motor? |
shift the
neutral running plane of the brushes to prevent sparking |
reduce the
reluctance of the magnetic path through the motor |
reverse the
flow of current in the field poles |
allow
current flow in the armature windings under a given pole to be in the
same direction at all times |
|
C |
What is the
characteristic of the mica used in the commutators of DC machinery? |
it is the
same hardness as the copper |
it is softer
than copper |
it is harder
than copper |
it is softer
than copper but wears away at a slower rate |
|
B |
In D.C.
motor construction, where are the commutating windings wound? |
opposite
main poles |
interpoles |
adjacent
main poles |
the rotor
core |
|
B |
In D.C.
motor construction, with regard to the individual armature coils'
ends, which statement is true? |
The coil
ends are crimped together with brush pigtails. |
The coil
ends are connected to the commutator bars. |
The coil
ends are imbedded into core slots. |
The coil
ends are spliced with the field windings |
|
D |
The counter
EMF of a DC motor is maximum when the __________. |
armature is
not turning |
motor is
almost up to rated speed |
armature has
just begun to turn |
motor is at
rated speed |
|
D |
In terms of
voltage potential and current sources, how are shunt wound, series
wound, and compound wound DC motors designed to operate? |
variable
potential, constant current DC sources |
constant
potential, constant current DC sources |
variable
potential, variable current DC sources |
constant
potential, variable current DC sources |
|
C |
If
overloading an electric motor becomes necessary in an emergency
situation, what should be done to prevent damage to the motor while
allowing sustained operation? |
hold thermal
overload relays open with blocks of wood |
increase the
residual magnetism value of windings to reduce eddy currents |
cool the
motor with portable blowers and fans |
inject small
amounts of CO2 into the windings for cooling |
|
C |
What is the
name of the DC motor speed control method utilized as shown in figure
"B" of the illustration? Illustration EL-0101 |
Burmeister-Wain |
Atlas-Copco |
Ward-Leonard |
Sperry-Rand |
|
A |
Which of the
following types of DC motors is considered to produce the highest
starting torque? |
series wound |
differential-compound wound |
cumulative-compound wound |
shunt wound |
|
D |
In a series
wound motor, the current passing through the field windings also
passes through what component? |
reactance
comparator |
shunt field |
laminations |
armature |
|
C |
How is the
speed of a series wound winch motor controlled? |
over current
protection devices in the motor |
the weight
of the load on the cargo boom |
varying the
voltage applied to the motor |
a hydraulic
speed-limiting governor |
|
A |
What type of
DC motor is never connected to a belt driven load? |
series wound |
shunt wound |
compound
wound |
permanent
magnet |
|
D |
Which of the
following types of DC motors has its field connected in parallel with
its armature? |
Universal |
Series wound |
Salient pole |
Shunt wound |
|
D |
As load is
added to a DC shunt motor, how will the motor respond? |
stop |
speed up |
maintain the
same speed |
slow down
slightly |
|
D |
If an
unloaded DC compound motor's shunt field were weakened by excessive
rheostat resistance or by an open circuit, how would the motor
respond? |
continue to
run at base speed |
stop because
of low flux |
slow down
and overheat |
over speed
due to reduced CEMF |
|
C |
In a
short-shunt cumulatively compound-wound DC motor, how is the shunt
field connected? |
in series
with the armature |
in series
with the amature and series field |
in parallel
with the armature |
in parallel
with the armature and series field |
|
D |
What is the
recommended method used to resurface an eccentric DC motor commutator? |
burnish it
with commutator stones |
use a hard
canvas wipe |
use a hand
stone |
turn it down
in the ship's lathe |
|
B |
Which of the
listed faults can only be eliminated by turning or grinding the face
of a commutator with a rigidly supported tool? |
Sparking
brushes |
Eccentricity |
Incorrect
brush angle |
High mica |
|
B |
For routine
cleaning of a commutator, what should be applied? |
a fine tooth
file to the commutator while running |
a canvas
wiper on the commutator while running |
an emery
cloth parallel to the axis of the commutator |
course
sandpaper in a slow back and forth motion across the commutator slots |
|
C |
What is an
important factor in minimizing D.C. motor commutator wear? |
ensuring a
very low brush current density |
keeping the
ambient humidity as low as possible |
establishing
the copper oxide surface film |
insuring
that brush pressure is excessive |
|
D |
In general,
what can cause D.C. propulsion motor brush sparking to be excessive? |
a dark
chocolate colored commutator |
brushes
positioned in the neutral plane |
a concentric
commutator |
incorrect
brush grade, pressure or position |
|
D |
What should
be included in performing proper maintenance of a D.C. motor's
commutator? |
painting the
face of the commutator with insulating varnish |
baking the
armature in an oven at 350°C for 8 hours annually |
coating the
copper surface with light machine oil for the first four hours of
operation |
side-cutting
the copper segments and undercutting the mica |
|
A |
One method
of testing for a reversed shunt field coil in a DC motor is by
connecting the coil to a low voltage source, and testing for polarity.
How is this done? |
placing a
magnetic compass near each field |
connecting a
copper jumper across the interpole connections |
placing an
iron bar across each field |
connecting a
test lamp across adjacent fields |
|
A |
In addition
to improper brush pressure or seating, what can result in excessive
sparking at the brushes of a DC propulsion motor? |
improper
positioning of brush rigging outside the neutral plane |
operating at
continuously varying loads such as during maneuvering |
reversed
main field polarity with respect to the armature |
reversed
armature polarity with respect to the field |
|
D |
How may
temporary repairs to an open DC propulsion armature coil be made,
allowing continued operation until permanent repairs can be made? |
connecting
the coil ends directly to a pair of negative brushes |
removing the
sparking brushes |
grounding
the coil ends and short circuiting the commutator bar |
disconnecting coil ends, insulating each, and short circuiting the two
commutator bars |
|
D |
What would
excessive sparking at the brushes of a running DC motor be an
indication of? |
water vapor
absorption |
increased
brush capacity |
normal
operation |
a dirty
commutator |
|
B |
Besides a
condition of overload, what could be a cause of an open armature
connection in a DC propulsion motor? |
excessive
starting resistance |
clogged
ventilation ducts |
tripped
circuit breaker |
low-load
operation |
|
C |
Which of the
listed conditions could cause a recently overhauled DC motor to have
excessively hot windings and sparking at the brushes? |
Low series
field current |
Excessive
humidity |
Reversed
interpole polarity |
High shunt
field current |
|
D |
An open in
the armature of a DC motor is suspected, but is not found by visual
inspection of the commutator. What would be the next step in
troubleshooting this problem? |
conduct an
insulation resistance test of the armature |
visually
inspect the armature windings |
test the
commutator for a ground |
conduct a
bar to bar test of the armature |
|
B |
If a DC
motor runs faster than designed, with all other conditions being
normal, what could be the possible cause? |
reversed
commutating pole |
open shunt
field coil |
overload |
open
armature coil |
|
D |
Besides for
checking for circuit continuity, what can an ohmmeter be used for in
diagnosing a DC motor? |
synchronous
speed |
undercut
mica |
reversed
polarity |
an open
field coil |
|
C |
How can a
shorted armature coil in a DC motor be detected? |
undercut
mica |
shiny
armature coil |
sparking at
the brushes |
worn grooves
in the armature |
|
A |
An internal
resistance is placed in series with the meter movement of which of the
following instruments? |
DC voltmeter |
AC ammeter |
AC frequency
meter |
DC ammeter |
|
A |
Which of the
listed meters uses a shunt connected in series with the load, but
parallel with the meter movement? |
Ammeter |
Power factor
meter |
Voltmeter |
Wattmeter |
|
B |
Why are
external shunts sometimes used with ammeters? |
to reduce
reactive power factor error |
to prevent
damage to the meter movement from heat generated by the internal shunt |
to increase
meter sensitivity |
to permit
shunts with larger resistances to be utilized |
|
C |
When a
resistor is used as a shunt and is connected in parallel with a meter
movement coil, what capability does this provide? |
a
measurement of circuit resistance |
an increased
accuracy of approximately 1.5 percent |
an extended
meter range |
this is
never done |
|
D |
What is the
instrument called a galvanometer used to measure? |
thickness of
galvanized metal |
resistance
of electrical wiring insulation |
quantity of
galvans in an electric circuit |
very small
amounts of current |
|
A |
Which of the
following would best describe a standard electric meter movement that
uses the principles of electromagnetism to measure current? |
moving coil
meter movement |
digital
movement |
hot-wire
movement |
rectifier
movement |
|
A |
To limit the
current flow through a DC voltmeter to as low a value as possible,
what is the moving coil circuit provided with? |
high series
resistance |
high
parallel resistance |
series
inductor |
external
shunt |
|
D |
A digital
multimeter, set up as a milliammeter on the 100 milliamp scale, is
known to have an accuracy of plus or minus 2%. A meter reading of 5.0
milliamps would indicate an actual line current between what two
values? |
4.5 and 5.5
milliamperes |
4.8 and 5.2
milliamperes |
4.0 and 6.0
milliamperes |
4.9 and 5.1
milliamperes |
|
D |
What is an
ammeter used to measure? |
total or
partial circuit resistance |
circuit
continuity |
the voltage
between two points in a circuit |
current flow
in a circuit |
|
D |
The clamp-on
AC ammeter consists essentially of a split-core and a rectifier-type
instrument connected to the secondary winding of a particular type of
transformer. Which type is used? |
control
transformer |
reactance
transformer |
potential
transformer |
current
transformer |
|
A |
In order to
take a current reading with a 'clamp-on' ammeter, what should be the
status of the jaws of the instrument? |
must be
fully closed so as to complete the magnetic circuit |
must be held
so as to not touch an adjacent conductor |
should
remain open while conducting measurements |
must be
clamped around all of the conductors of a cable |
|
D |
Whether
analog or digital, what are most AC voltmeters calibrated to measure? |
peak-to-peak
voltage |
average
voltage |
peak voltage
only |
root-mean-square voltage |
|
B |
A digital
multimeter is set up as an ohmmeter on the 1 kohm scale. What does a
display reading of 'OL' ohms as read across the ends of a wire
conductor indicate? |
a partial
short |
open circuit |
continuity |
a partial
ground |
|
C |
Which of the
listed statements is correct when using a digital multimeter set up as
an ohmmeter? |
It is
usually not possible for a digital multimeter to be set up as an
ohmmeter. |
With the
test leads shorted together, a reading of 'OL' ohms will be displayed. |
With the
test leads shorted together, a reading of 'zero' ohms will be
displayed. |
With the
test leads apart insulated from each other, a reading of 'zero' ohms
will be displayed. |
|
B |
Which of the
following conditions indicates a short circuited capacitor when
checking its condition with a digital multimeter set up as an
ohmmeter? |
The screen
immediately displays 'zero' ohms, but gradually climbs to 'OL' ohms. |
The screen
immediately displays 'zero' ohms and remains at this value. |
The screen
immediately displays 'OL' ohms, but gradually drops to 'zero' ohms. |
The screen
immediately displays 'OL' ohms and remains at this value. |
|
D |
Before
measuring an unknown resistance with an analog multimeter set up as an
ohmmeter, what should you do? |
change the
meter's batteries |
adjust the
meter's pointer to mid-scale |
center the
meter's pointer at infinity |
short the
test leads and calibrate the meter reading to 'zero' |
|
D |
What is an
ohmmeter used to measure? |
the amount
of current flow in a circuit |
voltage
between two points in a circuit |
circuit
power |
circuit
resistance |
|
A |
As shown in
figures "B" and "C" of the illustration, what should be the switch
position and which test lead terminal jacks should be used if your
intent is to measure DC currents anticipated as high as 200 milliamps?
Illustration EL-0047 |
switch
position "6" and terminal jacks "1 and 4" |
switch
position "6" and terminal jacks "2 and 4" |
switch
position "7" and terminal jacks "1 and 4" |
switch
position "7" and terminal jacks "2 and 4" |
|
B |
Circuit
resistance is usually measured off-line (de-energized) with an
ohmmeter. In the absence of an ohmmeter, however, resistance may be
INDIRECTLY measured on-line (energized) using what meter (or meters)? |
frequency
meter |
voltmeter
and an ammeter |
voltmeter
only |
ammeter only |
|
C |
What
practice could potentially damage a multimeter? |
placing the
test leads across a de-energized and isolated resistance to measure
resistance while in the voltmeter mode |
placing the
test leads across a de-energized and isolated resistance to measure
resistance while in the ammeter mode |
placing the
test leads across a voltage source to measure voltage while in the
resistance mode |
placing the
test leads in series with the load of a circuit to measure current
while in the voltmeter mode |
|
C |
As shown in
figure "A" of the illustrated digital multimeter screen, what would be
the significance of the symbol indicated by "2" being illuminated?
Illustration EL-0047 |
the selector
switch is in the resistance position and the meter leads are connected
across a PN junction of a transistor |
the selector
switch is in the continuity/diode test position and the secondary
function pushbutton is toggled for continuity |
the selector
switch is in the continuity/diode test position and the secondary
function pushbutton is toggled for diode |
the selector
switch is in the resistance position and the meter leads are connected
across a diode |
|
C |
If the
pointer fails to return to zero when a hand-cranked megger is
disconnected, what does this indicate? |
hair springs
are burned out |
megger is
out of calibration |
megger is
operating normally |
pointer is
stuck |
|
D |
Under what
circumstance would a hand-held portable phase sequence indicator be
used should the main switchboard mounted fixed phase sequence
indicator be inoperative? |
paralleling
alternators |
installing a
new synchroscope |
replacing a
defective solenoid |
preparing to
make the shore power connection |
|
C |
As shown in
the illustrated devices and symbols, which of the devices represents
an open general purpose relay? Illustration EL-0005 |
D |
C |
A |
B |
|
B |
Which of the
following illustrated manual motor starters represents the wiring
diagram illustrated in figure "A"? Illustration EL-0023 |
2 |
1 |
4 |
3 |
|
B |
An
across-the-line starter is typically used for which of the following
applications? |
Reduced-current starting of large motors |
Full-voltage
starting of motors |
Low torque
starting of small motors |
Low
resistance starting of DC motors |
|
A |
What is the
functional name of an electrical device which prevents simultaneous
energization of loads thereby preventing damage or injury. |
electrical
interlock device |
monitoring
device |
modulating
device |
mechanical
limit device |
|
B |
Which of the
following statements represents the main difference between a relay
and a contactor? |
Contactors
are made from silver and relays are made from copper. |
Contactors
contacts can handle heavier loads than relay contacts. |
Contactors
control current and relays control voltage. |
A relay is
series connected and a contactor is parallel connected. |
|
C |
Which of the
motors for the devices listed below is fitted with an instantaneous
overload relay? |
Machine tool |
Pump |
Winch |
Fan |
|
C |
What
functionality does a low-voltage protection circuit as used in
electric motor starting equipment provide? |
allow the
motor to restart automatically on restoration of voltage without
manually resetting |
trip out the
motor when the motor over speeds due to low voltage |
prevent the
motor from restarting automatically on restoration of voltage |
trip out the
motor when the motor develops a short circuit due to low voltage |
|
D |
Which of the
listed items will stop a motor due to a reduction in voltage and
automatically restart it when the voltage is restored to normal? |
Renewable
link fuse |
Non-renewable link fuse |
Low voltage
protection circuit |
Low voltage
release circuit |
|
A |
What is the
name of the type of motor control circuit that will not permit
automatic restarting after power is restored, following a power
failure? |
low voltage
protection |
low voltage
release |
overload
lockout |
reduced
voltage restart |
|
C |
Which of the
following statements is true concerning the motor controller circuit
shown in the illustration? Illustration EL-0004 |
The
controller is configured for reduced voltage starting. |
The
controller is configured for use with a three phase reversible
squirrel-cage induction motor. |
The
controller is configured for use with a three phase non-reversible
squirrel-cage induction motor. |
The
controller is configured for low voltage release. . |
|
D |
In the
illustration shown, what type of protection is provided the potable
pump drive motor? Illustration EL-0043 |
magnetic
overload protection and low voltage protection |
thermal
overload protection and low voltage protection |
magnetic
overload protection and low voltage release |
thermal
overload protection and low voltage release |
|
B |
A
three-phase, induction-type motor experiences an open in one phase.
Which of the listed automatic protective devices will prevent the
motor from being damaged? |
Over speed
trip |
Thermal
overload relay |
Three-pole
safety switch |
Magnetic
blowout coil |
|
C |
If the
circuit shown in the illustration were energized and operating
properly, which of the devices listed would be open? Illustration
EL-0007 |
Contact 'OL' |
The stop
push-button |
The start
push-button |
Auxiliary
contact 'M' |
|
D |
When a motor
is started by the controller shown in figure "C" of the illustration,
what circuit components are in the holding current flow path through
the control circuit while the motor is in operation? Illustration
EL-0010 |
the stop
button contacts, the "B2" contacts, the "M" contacts, the "M" coil and
the "OL" contacts |
the stop
button contacts, the "A2" contacts, the "M" coil and the "OL" contacts |
the stop
button contacts, the "A1" contacts, the "M" coil and the "OL" contacts |
the stop
button contacts, the "B1" contacts, the "M" contacts, the "M" coil and
the "OL" contacts |
|
B |
In the
illustrated motor controller, what do the contacts across terminals
"3" and "4" of the control circuit represent? Illustration EL-0017 |
thermal
overload heater |
normally-closed overload relay contact |
magnetic
overload coil |
normally-open overload relay contact |
|
C |
As shown in
the illustration, which of the following conditions will occur as a
result of a momentary loss of power? Illustration EL-0017 |
the
"off-run" selector switch will re-open, necessitating a manual
restarting of the motor. |
The normally-closed OL relay contacts will open requiring a manual
reset, necessitating a
manual
restarting of the motor. |
The motor
will automatically restart when power is restored. |
The
disconnect switch (DS) will re-open, necessitating a manual restarting
of the motor. |
|
A |
As shown in
the illustration, what type of starter is illustrated? Illustration
EL-0104 |
reduced
voltage primary resistance starter |
across-the-line starter |
reduced
voltage autotransformer starter |
reduced
voltage secondary resistance starter |
|
A |
In the
illustration shown, what would be the functional name for the coil
represented as '1S'? Illustration EL-0012 |
neutral
contactor coil (for autotransformer wye connection) |
0% contactor
coil |
1st speed
contactor coil |
start
contactor coil (for autotransformer connection to line) |
|
C |
As shown in
the illustration, assuming power is available at the control circuit,
which listed action will occur FIRST when the "off-run" switch is
placed in the "run" position? Illustration EL-0017 |
The
disconnect switch (DS) contacts close. |
The "OL"
relay contacts close. |
The
contactor coil "M" energizes. |
The main
contacts (3) "M" close, connecting the motor to line.. |
|
B |
As shown in
the illustrated electrically operated watertight door controller, how
is the rotation direction of the door motor reversed? Illustration
EL-0115 |
reversing
the direct current direction through the motor series field and
maintaining the same direct current direction through the motor
armature. |
reversing
the direct current direction through the motor armature and
maintaining the same direct current direction through the motor series
field |
reversing
the direct current direction through the motor series field and the
motor armature |
reversing
the direct current direction through the motor armature and
maintaining the same direct current direction through the motor shunt
field. |
|
C |
By what
means is the burning of controller contacts due to arcing, when
opening, prevented? |
coating the
contact surfaces lightly with petroleum jelly |
an
overvoltage release |
magnetic
blowout coils |
an over
current release |
|
B |
When rolling
over a DC main propulsion motor in local emergency mode or throttle
bypass mode, what must be done with the variable rheostat in terms of
turning the handle? |
turn quickly
to the fast position |
turn a
sufficient amount to assure armature rotation |
turn to the
fast position until the armature begins to rotate and then turned back
to slow |
turn quickly
to the mid position to energize the field |
|
C |
Which of the
following statements is true concerning the operation of modern marine
electric drive DC propulsion motors? |
The rotor
follows the frequency and phase sequence rotation of voltage applied
to the motor until it reaches the desired speed. |
The
cycloconverter is used to increase the voltage applied to the motor
until it reaches the desired speed. |
The
silicon-controlled rectifiers in the power converter are used to
control the voltage and current applied to the motor armature. |
The source
and load converters respond to a small reference voltage increasing
the frequency applied to the motor until it reaches the desired speed. |
|
B |
As shown in
figure "B" of the illustration, when the DC motor in figure "A" is
operating at minimum speed what are the armature and field
characteristics? Illustration EL-0153 |
The motor is
operating at maximum armature voltage and minimum field current. |
The motor is
operating at minimum armature voltage and maximum field current. |
The motor is
operating at maximum armature voltage and maximum field current. |
The motor is
operating at minimum armature voltage and minimum field current. |
|
A |
Before
working on an electric cargo winch master switch or controller, what
should be done? |
open the
circuit breaker in the power supply and tag-out |
heat the
switch box to remove any moisture |
spray the
gasket surface with a solvent |
drain
condensate from the box |
|
A |
Which of the
following represents the accepted method of cleaning dust and foreign
particles from electrical equipment while limiting damage to electric
components? |
Using a
vacuum cleaner to remove debris from the components. |
Carefully
using a soft copper bristle brush. |
Blowing a
high velocity stream of compressed air rapidly across the components. |
Using carbon
tetrachloride as a cleaning solvent to clean the components. |
|
A |
Moisture
damage, as a result of condensation occurring inside of the cargo
winch master switches, can be reduced by the use of what installed
equipment? |
using strip
heaters inside the switch box |
installing a
light bulb in the pedestal stand |
venting the
switch box regularly |
coating the
switch box internals with epoxy sealer |
|
D |
What damage
may occur to the components of a winch master control switch, if the
cover gasket becomes deteriorated? |
Sparking at
the winch motor brushes. |
Contamination of lube oil. |
Overheating
of the winch motor. |
Rapid
corrosion of switch components. |
|
B |
The set
point current at which a magnetic-type overload relay tends to trip
may be increased by turning the dashpot in the 'lower' direction. What
effect will this action have? |
increases
magnetic force on the plunger and requires more current to trip the
relay |
reduces
magnetic force on the plunger and requires more current to trip the
relay |
increases
magnetic force on the plunger and requires less current to trip the
relay |
reduces
magnetic force on the plunger and requires less current to trip the
relay |
|
C |
Which of the
following methods should be used to dress the face of silver-plated
contacts? |
Burnishing
with a burnishing tool |
Filing with
a mill file |
Sanding with
0000 sandpaper |
Knurling
with a knurling tool |
|
C |
Grease
coatings on electrical contact surfaces increase contact resistance.
How should grease accumulations be removed? |
10% solution
carbon tetrachloride solvent and water |
small wire
brush |
clean dry
cloth |
compressed
air jet |
|
C |
Which of the
following statements is true concerning the cleaning of electrical
contacts? |
Compressed
air should be used to blow out metallic dust. |
The contact
surfaces should be greased to increase contact resistance. |
Delicate
parts should be cleaned with a brush and an approved safety solvent. |
Magnetic
brushes should be used to remove metallic dust. |
|
C |
What item
(or items) constitute routine AC motor controller maintenance? |
blowing out
with high pressure compressed air |
cleaning
with soap and water |
performing a
visual inspection and tightening connections |
cleaning
with carbon tetrachloride |
|
B |
Using the
illustrated catalog number selection chart, determine the correct
catalog number for a motor starter that meets the following selection
criteria: a 3-pole, vertically mounted, NEMA non-reversing starter
with an open enclosure rated at 90 continuous amperes, fitted with an
electronic overload relay with a standard feature set and an operating
coil rated at 120 VAC/60Hz. Illustration EL-0180 |
AE19GNVB5G100 |
AN19KNVA5E100 |
AN19AN0A5E005 |
AN59GNVT5G100 |
|
B |
Which device
will stop the motor shown in the illustration in case of a
short-circuit (high current) motor fault? Illustration EL-0080 |
transformer
primary fuses FU4 and FU5 |
disconnect
switch fuses FU1, FU2, and FU3 |
transformer
secondary fuses FU6 and FU7 |
overload
relay heaters and overload relay NC contacts (OL) |
|
B |
If you hear
a loud buzzing noise coming from a magnetic motor controller, what
should you do? |
assume that
the motor is operating at a full load |
notify the
electrician or watch engineer of the problem |
assume that
the controller is operating normally |
feel the
outside of the casing with your hand to see if it is hot |
|
D |
The motor
fails to start on an attempted startup. With the start button
depressed, a voltmeter reading between 1 and 5, as illustrated in
figure "A", indicates line voltage available to the control circuit,
what should be your next step in the troubleshooting process?
Illustration EL-0007 |
insure that
the disconnect switch (DS) is closed |
test the
contactor coil "M" for continuity and replace if necessary |
test the
stop button for continuity and replace if necessary |
attempt to
reset the overload relay and determine the cause of the overload if
applicable |
|
A |
Why are
motor controllers seldom troubled by grounds? |
contactors
and relays are mounted on non-conducting panels |
shock mounts
on controller panels greatly reduce vibration |
special
insulation is used on wire for vital circuits |
cabinet
heaters always keep internal components dry |
|
A |
The motor
starts when the start button in the illustration is pushed, but stops
when the button is released. What is most likely the trouble?
Illustration EL-0007 |
an open
auxiliary "M" contact |
a corroded
contact on the disconnect switch (DS) at 'L3' |
an open "M"
contactor coil |
an open in
the stop button contact |
|
B |
What can be
the cause of excessive heat or burning contacts in an operating motor
controller? |
burned out
operating coil |
loose
connections or low contact pressure |
low motor
starting torque |
high ambient
temperature |
|
B |
The
illustrated motor fails to start and gives a loud hum when the start
button is depressed, what should then be your first action?
Illustration EL-0007 |
disassemble
the motor to fix the centrifugal switch so the start windings will be
energized |
push the
stop button to deenergize the "M" coil |
reset the
thermal overload |
hold the "M"
contactor closed by hand while wearing electrical safety gloves to get
motor started |
|
B |
In the
illustrated motor controller, the motor fails to start. A voltmeter
reading between 1 and 5 reads line voltage, while the voltmeter
reading between 2 and 5 reads 0 VAC. What is most likely the problem?
Illustration EL-0007 |
an open
start switch contact (when pushed in) |
an open stop
switch contact (when not pushed in) |
an open main
contactor "M" coil |
an overload
"OL" relay contact |
|
B |
If the motor
shown in the illustration will not start when the "off-run" switch is
placed in the run position, which of the listed components should be
checked FIRST? Illustration EL-0017 |
check the
overload relay (OL) heaters for continuity, replace as necessary |
check the
overload relay for tripped condition, reset as necessary |
check the
disconnect switch open, open as necessary |
check the
main contactor coil for continuity, replace as necessary |
|
D |
When
troubleshooting a motor controller, all indications are that a relay
coil should be energized. If there was no magnetic pull, with rated
voltage measured across the coil, what would be the most probable
cause? |
control fuse
is open |
auxiliary
contact in series with the coil is defective |
relay
armature is stuck |
coil is open |
|
C |
When
troubleshooting a magnetic controller, it is found that the contacts
are welded together. What is the most probable cause? |
high voltage
on the operating coil |
high ambient
temperature |
low voltage
on the operating coil |
excessive
operation at low load |
|
D |
As shown in
figure "A" and "B" of the illustration, the potable water pump is
short cycling by the action of the pressure switch as a result of an
unusually high level in the potable water hydro pneumatic header tank.
What is most likely the cause? Illustration EL-0043 |
The pressure
switch differential setting is set excessively high and the
differential must be decreased. |
The pressure
switch range adjustment is set too low and must be set higher. |
The potable
water hydro-pneumatic header tank has too much compressed air and some
must be bled off. |
The potable
water hydro-pneumatic header tank is in need of recharging with
compressed air due to absorption of air into the water over time. |
|
A |
If a
magnetic controller relay fails to drop out when the coil voltage is
removed from the relay, what is the probable cause? |
welded
contacts |
excessive
current |
excessive
spring tension |
overvoltage |
|
D |
A loud
buzzing noise coming from the contacts in a magnetic controller can be
caused by what condition? |
excessive
current |
bouncing of
contacts |
excessive
magnet gap |
dirt on
magnet faces |
|
C |
As shown in
figure "A" of the illustration, if in troubleshooting the control
circuit using on-line techniques with a voltmeter with the start
button depressed and the following readings are taken, what is the
problem? "X1" to "X2" reads 115 VAC; "1" to "X2" reads 115 VAC; "2" to
"X2" reads 0 VAC; and "3" to "X2" reads 0 VAC. Illustration EL-0123 |
the
secondary winding of the control transformer is open-circuited |
the start
button is open-circuited |
the stop
button is open-circuited |
the fuse is
blown |
|
D |
If a digital
multimeter is set up as shown in figure "A" of the illustration to
test an AC contactor coil, what would the display read if the coil is
open-circuited? Illustration EL-0214 |
110 V |
0.03 ohms |
22 ohms |
OL ohms |
|
A |
What can
cause the pitting or welding of controller contacts? |
insufficient
contact pressure |
low ambient
temperature |
excessive
spring pressure |
high ambient
temperature |
|
A |
If many
turns of an alternating current coil for a contactor become short
circuited, what will happen to the coil? |
it will
probably burn out immediately |
it will
operate on reduced current |
it will
experience a temperature will drop |
it will have
a higher resistance value |
|
A |
Which of the
following illustrated manual motor starters represents the wiring
diagram illustrated in figure "A"? Illustration EL-0023 |
1 |
2 |
3 |
4 |
|
B |
What is the
functional name of an electrical device which prevents simultaneous
energization of loads thereby preventing damage or injury? |
monitoring
device |
electrical
interlock device |
modulating
device |
mechanical
limit device |
|
B |
What is one
function of the movable cams in a drum-type winch motor controller? |
limit the
amount of load put on the motor |
regulate the
speed of the motor |
maintain
resistance contacts in clean condition |
insulate the
operating handle |
|
A |
Which of the
following statements represents the main difference between a relay
and a contactor? |
Contactors
contacts can handle heavier loads than relay contacts. . |
Contactors
are made from silver and relays are made from copper. |
A relay is
series connected and a contactor is parallel connected. |
Contactors
control current and relays control voltage. |
|
C |
What is the
purpose of an electro-magnetic relay? |
provide over
current protection during starting |
relay
voltages at increased power |
remotely
open and close contacts by action of a coil |
open a
circuit only in the event of overload |
|
A |
What is the
name of the type of motor control circuit that will not permit
automatic restarting after power is restored, following a power
failure? |
low voltage
protection |
overload
lockout |
reduced
voltage restart |
low voltage
release |
|
D |
As shown in
the illustration, by what means are all the 'MS' contacts are opened
and closed? Illustration EL-0073 |
operating
coils |
magnets |
solenoid
switches |
manual
operation of the master switches |
|
A |
Assuming the
ladder diagram of figure "A" and the corresponding input/output
diagram of figure "B" represents a simple PLC motor controller, what
statement is true? Illustration EL-0232 |
The input
switch is a maintained contact on-off selector switch, output "A" is
the motor contactor coil, and output "B" is a motor run status lamp
for the running condition. |
The input
switch is a maintained contact on-off selector switch, output "A" is
the motor contactor coil, and output "B" is a motor run status lamp
for the stopped condition. |
The input
switch is a momentary contact start button, output "A" is the motor
contactor coil, and output "B" is a motor run status lamp for the
stopped condition. |
The input
switch is a momentary contact start button, output "A" is the motor
contactor coil, and output "B" is a motor run status lamp for the
running condition. |
|
C |
If a
three-phase motor controlled by the control circuit illustrated in
figure "B" of the illustration, is running in the forward direction,
which of the following sequences must occur before the motor will
reverse rotation? Illustration EL-0011 |
First, the
motor must be stopped via the stop button, then normally open 'F'
contacts must re-close, and finally the reverse start button must be
depressed. |
First, the
motor must be stopped via the stop button, then normally closed 'F'
contacts must re-open, and finally the reverse start button must be
depressed. |
First, the
motor must be stopped via the stop button, then normally closed 'F'
contacts must re-close, and finally the reverse start button must be
depressed. |
First, the
motor must be stopped via the stop button, then normally open 'F'
contacts must reopen, and finally the reverse start button must be
depressed. |
|
A |
In the
illustrated solid-state "soft" starter for a three phase induction
motor as shown in figure "A", what is the name of the devices that are
controlled by the gate control circuits? Illustration EL-0060 |
thyristors |
varactors |
semiconductor diodes |
zener diodes |
|
A |
With what
kind of starting equipment are most three-phase induction motors of
five horsepower or less started? |
across-the-line starters |
resistor
starters |
autotransformer starters |
reactor
starters |
|
D |
Which of the
following contactors or relays has a timing function for the
transition from start to run? Illustration EL-0080 |
KM1 |
KM2 |
KM3 |
KA1 |
|
B |
Concerning
the illustrated motor controller circuit, where is the location of the
motor "run" indicator light? Illustration EL-0004 |
At the local
control station. |
At the
remote control station. |
There is no
motor "run" light. It is, instead, a motor "stopped" light. |
At the
motor. |
|
B |
As shown in
the illustrated steering hydraulic pump motor controller, what
statement is true? Illustration EL-0119 |
The pump
motor is protected by low voltage release and protected from motor
overload by overload trip |
The pump
motor is protected by low voltage release and protected from motor
overload by visual warning |
The pump
motor is protected by low voltage protection and protected from motor
overload by overload trip |
The pump
motor is protected by low voltage protection and protected from motor
overload by visual warning |
|
B |
As shown in
the illustration, what type of motor and motor starter are featured?
Illustration EL-0136 |
squirrel
cage induction motor with reduced voltage starting |
squirrel
cage induction motor with across-the-line starting |
synchronous
motor with across-the-line starting |
wound rotor
induction motor with across-the-line starting |
|
A |
As shown in
the illustrated feeder disconnect controller, what statement is true?
Illustration EL-0138 |
the feeder
disconnect contactor remains closed on a loss of power |
the feeder
disconnect contactor is electrically latched |
the feeder
disconnect contactor is electrically tripped |
the feeder
disconnect contactor is mechanically closed |
|
C |
As shown in
figure "A" of the illustration, what is the purpose of the "test
button"? Illustration EL-0178 |
The test
button is used to test the actual current trip value of the overload
relay. |
The test button is used to reset the now open normally closed relay
contacts after an overload
trip. |
The test
button is used to mimic an overload to test the trip function of the
overload relay. |
The test
button is used to reset the now closed normally open relay contacts
after an overload trip. |
|
D |
Which of the
following pictures represents a magnetic reversing or two-speed motor
starter? Illustration EL-0179 |
A |
B |
C |
D |
|
C |
By what
means is the burning of controller contacts due to arcing, when
opening, prevented? |
coating the
contact surfaces lightly with petroleum jelly |
an
overvoltage release |
magnetic
blowout coils |
an over
current release |
|
C |
As shown in
the illustration of an electrically operated watertight door
controller, what type of motor is used to open and close the
watertight door? Illustration EL-0115 |
Permanent
magnet DC motor |
Compound
wound DC motor |
Series wound
DC motor |
Shunt wound
DC motor |
|
C |
As shown in
the illustration of an electrically operated watertight door
controller, how is reversal of the direction of motor rotation
achieved? Illustration EL-0115 |
The shunt
field windings are reversed. |
The series
field windings are reversed. |
The armature
windings are reversed. |
Both the
series field and armature windings are reversed. |
|
D |
As shown in
the illustration of an electrically operated watertight door
controller, how is the motor stopped automatically when the door is
wedged closed? Illustration EL-0115 |
Momentarily
depressing open push-button switch. |
Action of
door open limit switch (LSO). |
Action of
motor overload (OL). |
Action of
door closed limit switch (LSC). |
|
C |
As shown in
the illustration of an electrically operated watertight door
controller, how is the motor stopped automatically when the door is
wedged open? Illustration EL-0115 |
Momentarily
depressing close push-button switch. |
Action of
motor overload (OL). |
Action of
door open limit switch (LSO). |
Action of
door closed limit switch (LSC). |
|
A |
Concerning
figure "A" of the illustration, if the illustrated PLC ladder diagram
is for a simple motor controller, what does "Input A" represent?
Illustration EL-0236 |
normally
open, momentary contact start pushbutton switch |
normally
open, maintained contact on-off selector switch |
normally
closed, maintained contact on-off selector switch |
normally
closed, momentary contact stop pushbutton switch |
|
A |
As shown in
figure "B" of the illustration, when the DC motor in figure "A" is
operating at base speed what are the armature and field
characteristics? Illustration EL-0153 |
The motor is
operating at maximum armature voltage and maximum field current. |
The motor is
operating at maximum armature voltage and minimum field current. |
The motor is
operating at minimum armature voltage and maximum field current. |
The motor is
operating at minimum armature voltage and minimum field current. |
|
B |
In the
illustrated motor controller, what do the contacts across terminals
"3" and "4" of the control circuit represent? Illustration EL-0017 |
magnetic
overload coil |
normally-closed overload relay contact |
thermal
overload heater |
normally-open overload relay contact |
|
B |
As shown in
the illustration, what is the purpose of the main contacts of
contactor "1S"? Illustration EL-0012 |
The "1S"
contactor connects the autotransformer in wye configuration during the
run period. |
The "1S"
contactor connects the autotransformer in wye configuration during the
starting/acceleration period. |
The "1S"
contactor connects the autotransformer to the line during the
starting/acceleration period. |
The "1S"
contactor connects the autotransformer in delta configuration during
the starting/acceleration period. |
|
B |
By what
means is the rotation of a three-phase induction motor reversed? |
disconnecting one of the three line leads to the stator |
interchanging any two of the three line leads to the stator |
permanently
disconnecting any two of the three line leads to the stator |
switching
the shunt field coil leads |
|
C |
Which of the
following statements is true concerning the motor controller circuit
shown in the illustration? Illustration EL-0004 |
The
controller is configured for use with a single phase induction motor. |
The control
circuit operates at full line voltage. |
The
controller is configured for across-the-line (direct-on-line)
starting. |
The
controller is configured for reduced voltage starting. |
|
D |
As shown in
the illustration, what type of motor and motor starter are featured?
Illustration EL-0137 |
non-reversing squirrel cage induction motor with reduced voltage
primary reactor starting |
reversing
squirrel cage induction motor with reduced voltage autotransformer
starting |
reversing
squirrel cage induction motor with across-the-line starting |
non-reversing squirrel cage induction motor with reduced voltage
autotransformer starting |
|
C |
A
three-phase, induction-type motor experiences an open in one phase.
Which of the listed automatic protective devices will prevent the
motor from being damaged? |
Over speed
trip |
Three-pole
safety switch |
Thermal
overload relay |
Magnetic
blowout coil |
|
A |
Referring to
figure "B" of the illustrated control circuit schematic diagram, which
of the following statements is true when the motor is running in the
forward direction? Illustration EL-0011 |
The normally
open (NO) "F" contacts are closed. |
The normally
closed (NC) "F" contacts are closed. |
The normally
open (NO) "R" contacts are closed. |
The normally
closed (NC) "R" contacts are open.. |
|
A |
As shown in
the two-speed single winding three phase motor connection diagrams
illustrated in figures "B", "C", and "D", what type of motor is shown
in the motor controller circuit illustrated in figure "A"?
Illustration EL-0118 |
unable to
determine whether the motor is a constant torque or variable torque
motor |
unable to
determine whether the motor is a variable torque or a constant
horsepower motor |
unable to
determine whether the motor is a constant torque or a constant
horsepower motor |
the motor is
a constant horsepower motor |
|
D |
As shown in
the illustration, using the instructions provided and Chart "A" and
Table "24", what size overload relay heater would be the proper
selection for the motor associated with the motor nameplate data shown
assuming the motor operates at sea level and that the motor and its
starter share the same ambient temperature? Illustration EL-0171 |
G30T21 |
G30T22 |
G30T19 |
G30T20 |
|
A |
As shown in
the illustration, by what means are all the 'MS' contacts are opened
and closed? Illustration EL-0073 |
manual
operation of the master switches |
solenoid
switches |
magnets |
operating
coils |
|
D |
With what
kind of starting equipment are most three-phase induction motors of
five horsepower or less started? |
autotransformer starters |
resistor
starters |
reactor
starters |
across-the-line starters |
|
A |
As shown in
the illustration, what type of motor is controlled as depicted in both
figure "A" and in figure "B"? Illustration EL-0144 |
three phase
wound rotor induction motor |
single phase
wound rotor induction motor |
three phase
synchronous motor |
three phase
squirrel cage induction motor |
|
D |
Which of the
following illustrated circuit schematics provides phase failure
protection for a three phase motor using load side current sensing
technology? Illustration EL-0222 |
B |
A |
C |
D |
|
D |
Which of the
following statements is true concerning the cleaning of electrical
contacts? |
Magnetic
brushes should be used to remove metallic dust. |
The contact
surfaces should be greased to increase contact resistance. |
Compressed
air should be used to blow out metallic dust. |
Delicate
parts should be cleaned with a brush and an approved safety solvent. |
|
A |
By what
means should motor controller contacts be routinely cleaned? |
wiping with
a clean dry cloth |
filing with
a bastard file |
blowing with
compressed air |
dressing
with crocus cloth |
|
B |
What item
(or items) constitute routine AC motor controller maintenance? |
cleaning
with carbon tetrachloride |
performing a
visual inspection and tightening connections |
blowing out
with high pressure compressed air |
cleaning
with soap and water |
|
B |
Before
working on an electric cargo winch master switch or controller, what
should be done? |
spray the
gasket surface with a solvent |
open the
circuit breaker in the power supply and tag-out |
heat the
switch box to remove any moisture |
drain
condensate from the box |
|
A |
What damage
may occur to the components of a winch master control switch, if the
cover gasket becomes deteriorated? |
Rapid
corrosion of switch components. |
Contamination of lube oil. |
Sparking at
the winch motor brushes. |
Overheating
of the winch motor. |
|
A |
Using the
illustrated catalog number selection chart, determine the correct
catalog number for a motor starter that meets the following selection
criteria: a 3-pole, vertically mounted, NEMA reversing starter with an
open enclosure rated at 45 continuous amperes, fitted with an
electronic overload relay with a ground fault feature set and an
operating coil rated at 24 VAC/60Hz. Illustration EL-0180 |
AN59GNVT5G045 |
AE19GNVB5G045 |
AN19AN0A5E005 |
CN16GNVT5G045 |
|
B |
As shown in
the illustration, what is the purpose of the Time Delay (TR) coil in
the circuit? Illustration EL-0104 |
Ensures the
motor cannot be started until the overload relays are reset. |
Allows the
motor to come up to speed at reduced voltage before bypassing the
starting resistors. |
Ensures the
motor cannot be started until the accelerating coil is energized. |
Allows the
motor to come up to speed before placing the starting resistors in the
circuit. |
|
D |
How may
temporary repairs to an open DC propulsion armature coil be made,
allowing continued operation until permanent repairs can be made? |
grounding
the coil ends and short circuiting the commutator bar |
removing the
sparking brushes |
connecting
the coil ends directly to a pair of negative brushes |
disconnecting coil ends, insulating each, and short circuiting the two
commutator bars |
|
D |
Which of the
listed conditions might contribute to very rapid wearing of a DC
machine's commutator bars? |
Aligning the
front and rear mica V-rings improperly |
An open
circuit in the armature |
A grounded
commutator bar |
Using
improper grade of carbon brushes |
|
D |
Which of the
listed colors properly describes a DC motor commutator when correct
commutation is taking place? |
Shiny blue |
Burnished
green |
Brick red |
Chocolate
brown |
|
B |
If the
contacts of a motor starter or controller fail to drop out when the
'stop' button is depressed, what could be the cause? |
stop
contacts are carrying insufficient current |
stop
contacts have become welded together |
starter
shading coil is loose |
starter
shading coil is broken |
|
A |
How is a
short in the shunt field of a DC motor best located? |
applying AC
voltage to the shunt field circuit and measuring the voltage drop
across each field coil |
isolating
each coil from the others and using a megohmmeter |
visual
inspection of the commutator |
using a
growler and hacksaw blade |
|
B |
An open in
the armature of a DC motor is suspected, but is not found by visual
inspection of the commutator. What would be the next step in
troubleshooting this problem? |
test the
commutator for a ground |
conduct a
bar to bar test of the armature |
visually
inspect the armature windings |
conduct an
insulation resistance test of the armature |
|
C |
What may
cause magnetic controller contacts to become welded together during
operation? |
an open coil |
excessive
magnetic gap |
low contact
pressure |
excessive
ambient temperature |
|
A |
Besides a
condition of overload, what could be a cause of an open armature
connection in a DC propulsion motor? |
clogged
ventilation ducts |
low-load
operation |
tripped
circuit breaker |
excessive
starting resistance |
|
B |
As shown in
figure "A" of the illustration, if in troubleshooting the control
circuit using on-line techniques with a voltmeter with the start
button depressed and the following readings are taken, what is the
problem? "X1" to "X2" reads 115 VAC; "1" to "X2" reads 0 VAC; "2" to
"X2" reads 0 VAC; and "3" to "X2" reads 0 VAC. Illustration EL-0123 |
the
secondary winding of the control transformer is open-circuited |
the fuse is
blown |
the stop
button is open-circuited |
the start
button is open-circuited |
|
C |
If a short
circuit in the armature of a DC motor occurs what would be the result? |
hum when
energized |
fail to
start |
spark at the
brushes |
run fast |
|
B |
What can
insufficient brush pressure on a DC motor cause? |
excess
residual magnetism |
sparking of
the brushes |
water vapor
absorption |
generator
overload |
|
D |
As shown in
the illustration, what mechanism will disconnect the motor from the
line in case of a sustained motor overload? Illustration EL-0080 |
transformer
secondary fuses FU6 and FU7 |
disconnect
switch fuses FU1, FU2, and FU3 |
transformer
primary fuses FU4 and FU5 |
overload
relay heaters and overload relay NC contacts (OL) |
|
D |
The motor
starts when the start button in the illustration is pushed, but stops
when the button is released. What is most likely the trouble?
Illustration EL-0007 |
an open in
the stop button contact |
an open "M"
contactor coil |
a corroded
contact on the disconnect switch (DS) at 'L3' |
an open
auxiliary "M" contact |
|
A |
In the
illustrated motor controller, the motor fails to start. A voltmeter
reading between 1 and 5 reads line voltage, while the voltmeter
reading between 2 and 5 reads 0 VAC. What is most likely the problem?
Illustration EL-0007 |
an open stop
switch contact (when not pushed in) |
an open main
contactor "M" coil |
an overload
"OL" relay contact |
an open
start switch contact (when pushed in) |
|
A |
If a digital
multimeter is set up as shown in figure "A" of the illustration to
test an AC contactor coil, what would the display read if the coil is
open-circuited? Illustration EL-0214 |
OL ohms |
0.03 ohms |
110 V |
22 ohms |
|
A |
Which of the
illustrated motors has a totally enclosed, fan-cooled (TEFC) motor
enclosure? Illustration EL-0001 |
A |
C |
D |
B |
|
B |
How is the
speed of a squirrel-cage induction motor determined? |
rotor
conducting bars resistance |
number of
stator poles |
diameter of
the stator |
rotor
winding resistance |
|
D |
In a
three-phase, squirrel-cage type, and induction motor, how is the
primary rotating magnetic field established? |
laminated
steel core and aluminum conductors in the rotor |
current
induced in the rotor windings |
interaction of the magnetic field caused by the induced current in the
squirrel-cage bars with
the
magnetic field of the stator |
application
of a three-phase voltage supply to the stator windings |
|
D |
Which of the
following statements is true concerning the operating characteristics
of a basic squirrel-cage induction motor? |
An increase
in motor load results in less slip. |
A decrease
in rotor speed produces a weaker magnetic field. |
A decrease
in rotor speed results in less current draw. |
Rotor slip
is dependent upon the motor load. |
|
C |
One item
listed on the nameplate of a cargo pump motor is 'degrees centigrade
rise.' What does the number stamped for this item represent? |
the minimum
temperature rise from no load to full load |
the normal
temperature rise from cold to hot |
the maximum
temperature rise above an ambient temperature of 40°C |
the maximum
temperature rise from absolute zero |
|
D |
How is the
full-load (rated) torque of an induction motor defined? |
maximum
torque developed by an overloaded motor with rated voltage and
frequency with appreciable drop in speed |
minimum
torque developed by the motor accelerating from rest to the speed at
which breakdown torque occurs |
torque
developed by the motor at the instant voltage is applied to the motor
at startup |
torque
developed by the motor operating at rated horsepower, speed, and
frequency |
|
C |
With respect
to electrical enclosure types, how may an electric motor be designed
and constructed? |
overload
proof |
ground proof |
explosion
proof |
short proof |
|
D |
What will be
the impact of reduced voltage applied to an AC induction motor during
the starting period? |
increase the
starting current and decrease the starting torque |
increase the
starting current and increase the starting torque |
decrease the
starting current and increase the starting torque |
decrease the
starting current and decrease the starting torque |
|
D |
Which of the
pictured motors is a square core shaded pole motor used to drive very
small electrical loads and is non-reversible __________. Illustration
EL-0208 |
C |
D |
A |
B |
|
D |
What type of
motor is illustrated by the schematic of figure "B" of the
illustration and what type of starting relay is used? Illustration
EL-0209 |
resistive
start, induction run (split phase) motor using a hot wire starting
relay |
resistive
start, induction run (split phase) motor using a current starting
relay |
resistive
start, induction run (split phase) motor using a potential starting
relay |
capacitor
start, induction run motor using a potential starting relay |
|
D |
How is the
difference between the synchronous speed of a three phase induction
motor and its operating speed correctly expressed? |
a decimal
fraction of full load speed |
a percent of
full load speed |
deviation |
slip |
|
B |
Assuming
that the 3-phase power source has a phase sequence of A-B-C and that
the motor is connected as shown in figure "A", if the motor has a
counterclockwise (CCW) rotation, what statement is true concerning the
motors connected as shown in the other figures? Illustration EL-0156
|
Motors "B",
"C", and "D" would all have a counterclockwise (CCW) rotation. |
Motors "B"
and "D" would have a clockwise (CW) rotation and motor "C" would have
a counterclockwise (CCW) rotation. |
Motors "B"
and "D" would have a counterclockwise (CCW) rotation and motor "C"
would have a clockwise (CW) rotation. |
Motors "B",
"C", and "D" would all have a clockwise (CW) rotation. |
|
B |
In general,
what type of starter would be used to connect polyphase induction
motors to full line voltage at the instant of start-up? |
auto-transformer starters |
across-the-line starters |
compensator
starters |
primary-resistor starters |
|
D |
Auto-transformer starters, sometimes called starting compensators, are
sometimes used with larger polyphase induction motors. What function
do they perform? |
they allow
the voltage to be either stepped up or down, depending on the
application, to ensure full torque |
they provide
a backup means of voltage regulation for emergency starting |
they
increase the voltage for 'across-the-line starting' |
they reduce
the voltage applied to the motor during the starting period |
|
D |
Which of the
following statements describes what will occur if the motor
torque-speed and current-speed curves shown in the illustration is
required to carry 150% of full load? Illustration EL-0056 |
The slip
value, stator current curve, and torque curve will all coincide. |
The slip
will decrease. |
The torque
will decrease. |
The stator
current will increase. |
|
B |
The
torque-speed and current-speed curves for a three-phase induction
motor with a squirrel-cage rotor are shown in figures "A" and "B" of
the illustration. Which of the following statements is true concerning
the depicted curves? Illustration EL-0056 |
The starting
current is nearly 1.5 times the normal full load current value. |
Starting
current is approximately 4.75 times the normal full load current
value. |
The pull-up
point on the torque curve is about 20% of the normal full load torque
value. |
Rated torque
and rated current occur at approximately 20% slip. |
|
A |
As shown in
the two-speed single winding three phase motor connection diagrams
illustrated in figure "B", what is the connection scheme associated
with low speed operation? Illustration EL-0118 |
series delta |
parallel wye |
parallel
delta |
series wye |
|
D |
According to
the sample sheet of a typical "List of Motors and Controls" as shown
in the illustration, which of the following motor applications
features a means of keeping the motor windings warm and dry when the
motor is idle? Illustration EL-0204 |
Main engine
sea water cooling pump |
Main fuel
oil transfer pump |
Main engine
piston cooling water pump |
Amidship
mooring winch |
|
C |
Universal
motors will operate on AC or DC current. In what application is this
type of motor generally? |
forced draft
fans |
large pump
motors |
portable
tools |
turbo
electric main motors |
|
B |
Of the
following listed single-phase induction motors, which has the highest
starting torque? |
shaded pole
motor |
capacitor
start induction run motor |
permanent
split capacitor motor |
resistive
start induction run motor |
|
B |
Which
statement is true concerning a split-phase induction motor? |
Motor speed
can be readily adjusted from zero to full speed. |
Motor
rotation can be reversed by reversing the leads on the starting
winding. |
Motor
rotation can be reversed without changing the windings or leads. |
The motor
will run as a generator with the proper wiring. |
|
B |
What is the
main purpose of the auxiliary winding on a split-phase, single-phase
motor? |
keep the
motor running in the event the main winding should fail |
provide
starting torque |
increase the
starting current |
limit the
starting voltage |
|
D |
What type of
rotor is used in the split-phase family of single-phase motors? |
Salient pole |
Drum |
Wound-rotor |
Squirrel-cage |
|
A |
A
shaded-pole motor is a specific type of motor included in what class
of motor? |
single-phase
induction motor |
three-phase
induction motor |
DC
compound-wound motor |
polyphase
synchronous motor |
|
C |
What is the
main function in the use of a capacitor for starting a single phase
motor? |
Reduce radio
interference |
Prolong the
life of the starting contacts |
Split the
phase to create greater starting torque |
Reduce the
phase angle |
|
A |
Which of the
pictured motors within the split phase family of single phase
induction motors represents a capacitor start, induction run motor?
Illustration EL-0146 |
A |
B |
D |
C |
|
C |
Within the
split phase family of single phase motors, what are the operational
characteristics of the motor shown in figure "B" of the illustration?
Illustration EL-0207 |
Relatively
low starting torque and relatively high running efficiency |
Relatively
low starting torque and relatively low running efficiency |
Relatively
high starting torque and relatively low running efficiency |
Relatively
high starting torque and relatively high running efficiency |
|
C |
As shown in
figures "A", "B", "C", and "D" of the illustration, what is the usual
means by which the rotation direction of the motor is reversed?
Illustration EL-0207 |
Interchanging leads T4 and T8 |
Interchanging leads L1 and L2 |
Interchanging leads T5 and T8 |
Interchanging leads T1 and T5 |
|
C |
What are the
operational characteristics of the split phase motor shown in figure
"B" of the illustration? Illustration EL-0215 |
The motor is
non-reversible and dual-voltage, configured for high volts. |
The motor is
reversible and dual-voltage, configured for low volts. |
The motor is
reversible and dual-voltage, configured for high volts. |
The motor is
non-reversible and dual-voltage, configured for low volts. |
|
B |
What is the
purpose of the squirrel-cage windings included as part of a
synchronous motor? |
provide more
precise balancing |
provide a
means for starting |
produce a
higher power factor |
eliminate
arcing between the stator and the frame |
|
D |
What is the
function of the squirrel cage windings installed on a synchronous
motor rotor? |
provide
excitation |
eliminate
slippage |
increase
efficiency |
provide
starting torque |
|
A |
What causes
the rotor of a synchronous motor to operate in synchronism with the
rotating field? |
the rotor is
magnetically locked into step with the rotating magnetic field by the
excitation current |
the
amortisseur (damper) windings |
the field
strength varies directly with rotor slip |
the stator
flux rotates in the opposite direction |
|
D |
What is the
most common source of excitation for the rotor of a synchronous motor? |
a step-up
transformer |
an AC power
supply |
a half-wave
rectifier |
a DC power
supply |
|
D |
An increase
in which of the listed conditions will increase the speed of a
synchronous electric motor? |
Inductance |
Voltage |
Armature
current |
Frequency |
|
B |
What is the
characteristic of an wound rotor induction motor with maximum rheostat
resistance inserted in the rotor circuit during starting? |
relatively
high starting torque and high stator current |
relatively
high starting torque and low stator current |
relatively
low starting torque and low stator current |
relatively
low starting torque and high starting current |
|
D |
For what
purpose is the variable resistance placed in the rotor circuit of a
wound-rotor induction motor provided? |
frequency
control |
voltage
control |
torque
control |
speed
control |
|
B |
What is the
characteristic of a wound-rotor induction motor, with a high
resistance inserted in series with the rotor winding at startup? |
relatively
low starting torque and low stator current |
relatively
high starting torque and low stator current |
relatively
high starting torque and high stator current |
relatively
low starting torque and high stator current |
|
C |
As shown in
the illustrated wound-rotor induction motor how is the direction of
rotation of the motor reversed? Illustration EL-0148 |
Any two of
the "M1, M2, and M3" leads are reversed only. |
Any two of the "T1, T2, and T3" leads are reversed and any of the two
"M1, M2, and M3"
leads
must be reversed as well. |
Any two of
the "T1, T2, and T3" leads are reversed only. |
It is not
possible to change the direction of rotation of a wound rotor
induction motor. |
|
C |
When
performing routine AC motor maintenance what should be included? |
inspection
of the motor's internals for loose rotor bars or field poles |
verifying
RPM if a synchronous motor |
temperature
readings at normal loads to detect abnormal temperature rises |
rotor
balance check |
|
A |
What is a
useful instrument for checking 3-phase AC motor performance by
measuring possible unbalanced currents? |
clamp-on
ammeter |
vibrating-reed frequency meter |
D'Arsonval
iron-vane probe |
hand or
battery-operated megger |
|
D |
For what
reason should engine room watchstanders keep a constant check on the
loads carried by electric motors? |
energy is
wasted if full loading is not utilized |
residual
magnetism may increase |
low loads
necessitate frequent insulation cleaning |
exceeding
nameplate currents shortens useful life |
|
D |
Which of the
following statements represents the FIRST step in seating new brushes
on slip rings? |
Press the
brushes against the slip ring with a wood block. |
Apply
seating compound under the brushes and run at no load for 2 hours. |
Increase
brush pressure and run at no load for 3 to 4 hours. |
Lay
sandpaper between the brush and the slip ring and slide the sandpaper
back and forth under the brush. |
|
A |
By
periodically checking the stator-to-rotor air gap clearance in an
induction motor with a feeler gauge, what is prevented? |
rotor
contact with the stator |
electrical
damage to the bearings |
damage to
the motor bearings |
axial
misalignment of the rotor |
|
B |
A digital
multimeter is set up as shown in the illustration to evaluate the
single-circuit stator windings of a squirrel cage induction
three-phase motor. The following readings are taken: From T1 to T2
reads "OL" ohms. From T2 to T3 reads "OL" ohms. From T3 to T1 as shown
reads "1.6" ohms. What condition is indicated? Illustration EL-0219 |
Phase A
(associated with T1) and Phase C (associated with T3) are
short-circuited. Phase B (associated with T2) is undamaged. |
Phase A
(associated with T1) and Phase C (associated with T3) are undamaged.
Phase B (associated with T2) is open-circuited. |
Phase A
(associated with T1) and Phase C (associated with T3) are
open-circuited. Phase B (associated with T2) is undamaged. |
Phase A
(associated with T1) and Phase C (associated with T3) are undamaged.
Phase B (associated with T2) is short-circuited. |
|
B |
What would
be the effect of carrying field excitation excessively high on a
synchronous motor? |
a tendency
for the motor to over speed |
a tendency
for the motor to overheat |
a loss of
motor speed regulation |
a tendency
for the motor to fall out of step |
|
C |
A
single-phase capacitor-start induction motor starts, comes up to about
75% rated speed, slows down to a lower speed, and accelerates again.
Where is the problem most likely to be? |
running
centrifugal switch |
starting
capacitor |
running
winding |
starting
winding |
|
B |
If the
centrifugal switch or relay used for cutting out the starting winding
of a split-phase induction motor fails to open once the motor is in
operation, what will be the result? |
the motor
torque will be above normal at rated speed |
the starting
winding will burn out |
the motor
will immediately stall under load |
the motor
will over speed |
|
D |
The leads
from a ohmmeter are attached to the leads of the opposite ends of an
AC motor stator field coil. If a reading of infinity is obtained, what
does this indicate? |
grounded
field coil |
shorted
field coil |
shunted
field coil |
open field
coil |
|
C |
In testing a
three-phase delta-connected winding for an open circuit using an
ohmmeter, what must be done? |
measure the
voltage across the open connections while testing |
test the
windings as parallel groups to avoid short circuiting |
if possible,
open the delta-connections to avoid shunting the phase being tested |
test each
phase with all connections intact |
|
B |
If a
single-phase capacitor start induction motor fails to start, but
instead hums without starting, what is most likely to be the problem? |
a blown fuse |
an open
start capacitor |
a shorted
centrifugal switch |
a tripped
circuit breaker |
|
C |
If a
three-phase induction motor is operated under a light load and it
develops an open in one of its supply lines, what will be the result? |
the motor
will run cooler due to reduced current flow |
the motor
will stop |
the motor
continue to run, but will vibrate and have reduced torque |
the motor
will speed up due to the reduced number of poles |
|
C |
Which of the
following methods should be used to test for an 'open' stator winding
coil in a wye-connected AC squirrel cage induction motor? |
Use a
growler, listening for noise and vibration to increase when over an
open coil. |
Test with an
ohmmeter, with one test lead on the shaft, and the other test lead to
each of the disconnected motor leads in succession and compare the
resistances |
Test with an
ohmmeter with the test leads across each pair disconnected motor lead
leads in succession and compare resistances. |
Use a
growler, listening for noise and vibration to diminish when over an
open coil. |
|
D |
In using a
portable growler for the purpose of locating a shorted stator coil in
an AC motor as shown in the illustration, what statement is true as
the feeler is moved from slot to slot around the stator? Illustration
EL-0200 |
The feeler
will vibrate in synchronism with the 60 Hz AC power source and produce
a growling noise when the feeler is moved over a slot which does NOT
contain a shorted coil. |
The feeler
will vibrate in synchronism with the 60 Hz AC power source and produce
a growling noise when the feeler is moved over a slot containing an
open coil. |
The feeler
will remain motionless with NO vibration or noise when the feeler is
moved over a slot containing a shorted coil. |
The feeler
will vibrate in synchronism with the 60 Hz AC power source and produce
a growling noise when the feeler is moved over a slot containing a
shorted coil. |
|
C |
When
troubleshooting AC motors, what can a portable growler be used to
locate? |
open field
coils |
grounded
field coils |
shorted
stator coils |
grounded
stator coils |
|
B |
When testing
the rotor of a synchronous motor for short circuits, a low voltage
source is applied across the rotor coils through the collector rings.
What would be the indication of a short-circuited coil? |
high voltage
drop reading, while the other coil readings will have an equal or
lower value |
low or zero
voltage drop reading, while the other coils will have higher readings |
steady
voltmeter reading, while the other coil readings are fluctuating |
fluctuating
voltmeter reading, while the other coil readings are steady |
|
A |
Which of the
listed instruments can be best used to locate a grounded field coil in
a synchronous motor onboard ship? |
Megohmmeter |
Voltmeter |
Frequency
meter |
Multimeter |
|
C |
Which of the
illustrated motors has an open, drip-proof (ODP) motor enclosure?
Illustration EL-0001 |
A |
B |
C |
D |
|
C |
Regarding an
induction motor, what does the power developed by the rotor
automatically adjust itself to? |
speed
required to drive the load |
torque
developed by the rotating field |
power
required to drive the load |
current flow
in the motor stator |
|
B |
Which of the
illustrated motors has an open motor enclosure? Illustration EL-0001 |
A |
B |
C |
D |
|
A |
Which of the
following motors has a frame configuration for solid base mounting
only? Illustration EL-0184 |
A |
B |
C |
D |
|
A |
What is he
most practical method of controlling the RPM of a multi-speed AC motor
operating at a constant frequency? |
change the
number of operating poles |
change the
input voltage |
change the
power factor |
change the
number of brushes |
|
D |
Auto-transformer starters, sometimes called starting compensators, are
sometimes used with larger polyphase induction motors. What function
do they perform? |
they allow
the voltage to be either stepped up or down, depending on the
application, to ensure full torque |
they provide
a backup means of voltage regulation for emergency starting |
they
increase the voltage for 'across-the-line starting' |
they reduce
the voltage applied to the motor during the starting period |
|
D |
What will be
the impact of reduced voltage applied to a motor during the starting
period? |
increase the
starting current and decrease the acceleration time |
decrease the
starting current and decrease the acceleration time |
increase the
starting current and increase the acceleration time |
decrease the
starting current and increase the acceleration time |
|
D |
As shown in
figure A" of the illustrated motor nameplate, how much current could
the motor safely draw on a continuous basis at sea level without
overheating? Illustration EL-0171 |
156 amps |
142 amps |
163 amps |
187 amps |
|
A |
Which type
of AC single-phase motor will also operate on direct current? |
Series-wound |
Repulsion-start |
Shaded-pole |
Split-phase |
|
B |
Which
statement is true concerning a split-phase induction motor? |
Motor speed
can be readily adjusted from zero to full speed. |
Motor
rotation can be reversed by reversing the leads on the starting
winding. |
Motor
rotation can be reversed without changing the windings or leads. |
The motor
will run as a generator with the proper wiring. |
|
A |
What is the
main purpose of the auxiliary winding on a split-phase, single-phase
motor? |
provide
starting torque |
keep the
motor running in the event the main winding should fail |
increase the
starting current |
limit the
starting voltage |
|
B |
What type of
rotor is most commonly used in the split-phase family of single-phase
motors? |
Drum |
Squirrel-cage |
Salient pole |
Wound-rotor |
|
B |
A
shaded-pole motor is a specific type of motor included in what class
of motor? |
polyphase
synchronous motor |
single-phase
induction motor |
DC
compound-wound motor |
three-phase
induction motor |
|
D |
What is the
main function in the use of a capacitor for starting a single phase
motor? |
Prolong the
life of the starting contacts |
Reduce the
phase angle |
Reduce radio
interference |
Split the
phase to create greater starting torque |
|
C |
Which of the
pictured motors within the split phase family of single phase
induction motors represents a split phase, resistive start, induction
run motor? Illustration EL-0146 |
A |
B |
C |
D |
|
D |
Within the
split phase family of single phase motors, what are the operational
characteristics of the motor shown in figure "A" of the illustration?
Illustration EL-0207 |
Relatively
high starting torque and relatively low running efficiency |
Relatively
low starting torque and relatively high running efficiency |
Relatively
high starting torque and relatively high running efficiency |
Relatively
low starting torque and relatively low running efficiency |
|
D |
As shown in
figures "A", "B", "C", and "D" of the illustration, what is the usual
means by which the rotation direction of the motor is reversed?
Illustration EL-0207 |
Interchanging leads T4 and T8 |
Interchanging leads T1 and T5 |
Interchanging leads L1 and L2 |
Interchanging leads T5 and T8 |
|
C |
What are the
operational characteristics of the split phase motor shown in figure
"A" of the illustration? Illustration EL-0215 |
The motor is
reversible and dual-voltage, configured for high volts. |
The motor is
non-reversible and dual-voltage, configured for low volts. |
The motor is
reversible and dual-voltage, configured for low volts. |
The motor is
non-reversible and dual-voltage, configured for high volts. |
|
A |
How is the
difference between the synchronous speed of a three phase induction
motor and its operating speed correctly expressed? |
slip |
a percent of
full load speed |
deviation |
a decimal
fraction of full load speed |
|
B |
Which of the
listed motors will operate at the highest RPM, assuming that each
operates at the same frequency? |
A four-pole
induction motor under no load. |
A four-pole
synchronous motor under normal load. |
A six-pole
induction motor under full load. |
A six-pole
synchronous motor under normal load. |
|
B |
Assuming
that the 3-phase power source has a phase sequence of A-B-C and that
the motor is connected as shown in figure "A", if the motor has a
clockwise (CW) rotation, what statement is true concerning the motors
connected as shown in the other figures? Illustration EL-0156 |
Motors "B",
"C", and "D" would all have a counterclockwise (CCW) rotation. |
Motors "B"
and "D" would have a counterclockwise (CCW) rotation and motor "C"
would have a clockwise (CW) rotation. |
Motors "B"
and "D" would have a clockwise (CW) rotation and motor "C" would have
a counterclockwise (CCW) rotation. |
Motors "B",
"C", and "D" would all have a clockwise (CW) rotation. |
|
A |
In general,
what type of starter would be used to connect polyphase induction
motors to full line voltage at the instant of start-up? |
across-the-line starters |
compensator
starters |
primary-resistor starters |
auto-transformer starters |
|
C |
The
torque-speed and current-speed curves for a three-phase induction
motor with a squirrel-cage rotor are shown in figures "A" and "B" of
the illustration. Which of the following statements is true concerning
the depicted curves? Illustration EL-0056 |
Rated torque
and rated current occur at approximately 20% slip. |
The starting
current is nearly 1.5 times the normal full load current value. |
Starting
current is approximately 4.75 times the normal full load current
value. |
The pull-up
point on the torque curve is about 20% of the normal full load torque
value. |
|
D |
In a
three-phase, squirrel-cage type, induction motor, how is the primary
rotating magnetic field established? |
current
induced in the rotor windings |
laminated
steel core and aluminum conductors in the rotor |
interaction of the magnetic field caused by the induced current in the
squirrel-cage bars with
the
magnetic field of the stator |
application
of a three-phase voltage supply to the stator windings |
|
B |
As shown in
the two-speed single winding three phase motor connection diagrams
illustrated in figure "B", what is the connection scheme associated
with low speed operation? Illustration EL-0118 |
parallel
delta |
series delta |
parallel wye |
series wye |
|
D |
What type of
AC motor would use a rheostat in the rotor circuit to vary the speed
of the motor? |
synchronous
motor |
regenerative
braking motor |
squirrel-cage induction motor |
wound-rotor
induction motor |
|
C |
A degree of
control over the speed of a slip ring induction motor can be obtained
by what means? |
inserting
resistance into the stator circuit |
adjusting
governor linkage |
inserting
resistance into the rotor circuit |
changing the
number of phases to the motor |
|
D |
What is the
characteristic of a wound-rotor induction motor, with a high
resistance inserted in series with the rotor winding at startup? |
relatively
low starting torque and low stator current |
relatively
low starting torque and high stator current |
relatively
high starting torque and high stator current |
relatively
high starting torque and low stator current |
|
A |
Which of the
following physical characteristics does a three-phase wound-rotor
induction motor possess that a squirrel cage induction motor does not? |
Slip rings |
A
centrifugal switch |
Compensating
windings |
A commutator |
|
C |
As shown in
the illustrated wound-rotor induction motor, what statement is true
concerning motor lead connections? Illustration EL-0148 |
The "M1, M2,
and M3" motor leads are directly connected to the rotor windings and
the "T1, T2, and T3" motor leads are connected to the stator windings
via slip rings and brushes. |
The "T1, T2,
and T3" motor leads are connected to the rotor windings via slip rings
and brushes and the "M1, M2, and M3" motor leads are directly
connected to the stator windings. |
The "M1, M2,
and M3" motor leads are connected to the rotor windings via slip rings
and brushes and the "T1, T2, and T3" motor leads are directly
connected to the stator windings. |
The "T1, T2,
and T3" motor leads are directly connected to the rotor windings and
the "M1, M2, and M3" motor leads are connected to the stator windings
via slip rings and brushes. |
|
C |
By what
means is a synchronous motor started and brought nearly to synchronous
speed? |
By the use
of compensating windings, also known as starting windings. |
By the use
of starting capacitors, also known as condensers. |
By the use
of a squirrel-cage induction winding, also called an amortisseur
winding. |
By the use
of interpoles, also known as commutating poles. |
|
D |
Concerning
the operating characteristics of a synchronous motor, what statement
is true? |
The
synchronous motor initially starts as a synchronous motor and when it
approaches synchronous speed, the motor continues to run as a
synchronous motor. |
The
synchronous motor initially starts as a synchronous motor and when it
approaches synchronous speed, the motor then runs as an induction
motor. |
The
synchronous motor initially starts as an induction motor and when it
approaches synchronous speed, the motor continues to run as an
induction motor. |
The
synchronous motor initially starts as an induction motor and when it
approaches synchronous speed, the motor then runs as a synchronous
motor. |
|
C |
Assuming
that a three phase synchronous motor is separately excited, what
statement is true concerning power supplies? |
The rotor
windings via slip rings and brushes are connected to a three phase AC
power source, and the stator winding is directly connected to a DC
power source. |
The rotor
winding via slip rings and brushes is connected to a single phase AC
power source, and the stator winding is directly connected to a three
phase AC power source. |
The rotor
winding via slip rings and brushes is connected to a DC power source,
and the stator windings are directly connected to a three phase AC
power source. |
The rotor
winding via slip rings and brushes is connected to a three phase AC
power source, and the stator winding is directly connected to a single
phase AC power source. |
|
D |
Occasionally
a synchronous motor is configured without an external shaft to drive a
load. In this case, the sole purpose of the synchronous motor is
improving overall power factor of an electrical distribution system.
What is the name of the synchronous motor so constructed? |
Synchronous
compensator |
Motor-generator |
Synchronous
converter |
Synchronous
condenser |
|
C |
Not only can
a synchronous motor drive a load with greater efficiency than an
induction motor, a fringe benefit of the synchronous motor is the
ability for power factor correction. What statement is true? |
If the
overall plant has a lagging power factor, the synchronous motor is
over-excited. |
If the
overall plant has a lagging power factor, the synchronous motor is
normally-excited. |
If the
overall plant has a unity power factor, the synchronous motor is
normally-excited. |
If the
overall plant has a leading power factor, the synchronous motor is
under-excited. |
|
B |
In terms of
voltage potential and current sources, how are shunt wound, series
wound, and compound wound DC motors designed to operate? |
variable
potential, variable current DC sources |
constant
potential, variable current DC sources |
constant
potential, constant current DC sources |
variable
potential, constant current DC sources |
|
B |
How can the
direction of rotation of a DC motor be reversed? |
wiring the
field and armature in series |
reversing
the field or armature connections |
reversing
both the field and the armature connections |
wiring the
field and armature in parallel |
|
D |
What is the
name of the DC motor speed control method utilized as shown in figure
"B" of the illustration? Illustration EL-0101 |
Sperry-Rand |
Atlas-Copco |
Burmeister-Wain |
Ward-Leonard |
|
B |
From the
instant of start-up, through the acceleration period, and until the
motor reaches rated speed, when is the counter EMF produced in the
windings of a DC motor 'zero'? |
motor is at
rated speed |
armature is
not yet turning |
armature has
just begun to turn |
motor is
almost up to rated speed |
|
B |
Which of the
following statements describes what will happen when both the polarity
of the field poles, and the direction of current to the brushes of a
DC motor are reversed? |
The
direction of rotation of the armature will be reversed. |
The
direction of rotation of the armature will remain the same. |
The motor
will not start. |
The field
pole windings will become overheated. |
|
A |
As shown in
figure "B" of the illustration, what does the M-G set's three-phase
drive motor mechanically drive? Illustration EL-0101 |
the DC
generator armature |
the DC
generator field |
the DC motor
armature |
the field
rectifier |
|
D |
If a DC
motor has its armature and field connected across a resistor when the
motor is disconnected from its power supply, what statement is true? |
The motor
has the proper connections for across the line starting. |
The motor
has the proper connections for an automatic strip heater. |
The motor is
set up for a reversing controller circuit. |
The motor
will slow down by the process of dynamic braking. |
|
B |
What is an
advantage of DC motors over AC motors? |
DC motors
can be started across the line whereas AC motors cannot |
DC motors
offer a more effective means of controlling speed than AC motors |
DC motors
require less maintenance than AC motors |
DC motors
are less expensive than AC motors |
|
D |
The torque
produced by a DC motor armature is the multiplication product of two
factors, one being the density of the magnetic flux which is dependent
upon the field current. What is the other multiplication factor? |
armature
resistance |
armature
voltage drop |
armature
conductance |
armature
current |
|
A |
As shown in
the illustration, which brush holder would be appropriate to use in a
bidirectional motor? Illustration EL-0029 |
radial mount |
trailing
mount only |
leading
mount only |
both leading
and trailing mount |
|
B |
As shown in
the illustration, which brush holder is of the reaction type?
Illustration EL-0029 |
2 |
4 |
1 |
3 |
|
B |
Which of the
following types of DC motors is considered to produce the highest
starting torque? |
cumulative-compound wound |
series wound |
shunt wound |
differential-compound wound |
|
B |
In a series
wound motor, the current passing through the field windings also
passes through what component? |
reactance
comparator |
armature |
shunt field |
laminations |
|
C |
How is the
speed of a series wound winch motor controlled? |
over current
protection devices in the motor |
the weight
of the load on the cargo boom |
varying the
voltage applied to the motor |
a hydraulic
speed-limiting governor |
|
D |
What type of
DC motor is never connected to a belt driven load? |
compound
wound |
shunt wound |
permanent
magnet |
series wound |
|
D |
What type of
DC motor has extremely high starting torque, but has poor inherent
speed regulation? |
compound
wound |
permanent
magnet |
shunt wound |
series wound |
|
C |
The wiring
diagram found in figure "C" of the illustration represents what type
of DC motor? Illustration EL-0054 |
shunt wound |
compound
wound with long shunt |
series wound |
compound
wound with short shunt |
|
D |
What type of
DC motor has relatively low starting torque, but has excellent
inherent speed regulation? |
series wound |
compound
wound |
permanent
magnet |
shunt wound |
|
B |
In a shunt
wound DC motor, how is the shunt field connected? __________. |
The shunt
field is wired in series with the armature, but in parallel with the
commutating and compensating windings. |
The shunt
field is wired in parallel with the armature circuit, including
armature, commutating, and compensating windings. |
The shunt
field is wired in series with the armature circuit, including
armature, commutating, and compensating windings. |
The shunt
field is wired in parallel with the armature, but in series with the
commutating and compensating windings. |
|
A |
What are the
characteristics of the field winding of a shunt wound motor? |
The
shunt-field coils are wound with many turns of very fine wire. |
The
shunt-field coils are wound with only a few turns of very fine wire. |
The
shunt-field coils are wound with only a few turns of very heavy wire. |
The
shunt-field coils are wound with many turns of very heavy wire. |
|
D |
The wiring
diagram found in figure "A" of the illustration represents what type
of DC motor? Illustration EL-0054 |
series wound |
compound
wound with long shunt |
compound
wound with short shunt |
shunt wound |
|
C |
What
statement is true concerning speed control of a shunt wound DC motor? |
For armature
rheostat control, the greater the resistance the lower the motor
speed. For field rheostat control, the greater the resistance the
lower the motor speed. |
For armature
rheostat control, the greater the resistance the higher the motor
speed. For field rheostat control, the greater the resistance the
higher the motor speed. |
For armature
rheostat control, the greater the resistance the lower the motor
speed. For field rheostat control, the greater the resistance the
higher the motor speed. |
For armature
rheostat control, the greater the resistance the higher the motor
speed. For field rheostat control, the greater the resistance the
lower the motor speed. |
|
C |
The wiring
diagram found in figure "B" of the illustration represents what type
of DC motor? Illustration EL-0054 |
differentially compounded short-shunt |
cumulatively
compounded short-shunt |
cumulatively
compounded long-shunt |
differentially compounded long-shunt |
|
B |
Which of the
listed DC compound motor connection schemes is the most commonly used? |
differentially compounded long-shunt |
cumulatively
compounded long-shunt |
differentially compounded short-shunt |
cumulatively
compounded short-shunt |
|
D |
When a
compound wound DC motor is cumulatively compounded, what does this
mean? |
The current
flow direction in each series-field coil is in the opposite direction
as the current flow direction in its corresponding shunt-field coil,
in which case the field fluxes are additive. |
The current
flow direction in each series-field coil is in the opposite direction
as the current flow direction in its corresponding shunt-field coil,
in which case the field fluxes are subtractive. |
The current
flow direction in each series-field coil is in the same direction as
the current flow direction in its corresponding shunt-field coil, in
which case the field fluxes are subtractive. |
The current
flow direction in each series-field coil is in the same direction as
the current flow direction in its corresponding shunt-field coil, in
which case the field fluxes are additive. |
|
C |
When a
compound wound DC motor is differentially compounded, what does this
mean? |
The current
flow direction in each series-field coil is in the same direction as
the current flow direction in its corresponding shunt-field coil, in
which case the field fluxes are additive. |
The current
flow direction in each series-field coil is in the same direction as
the current flow direction in its corresponding shunt-field coil, in
which case the field fluxes are subtractive. |
The current
flow direction in each series-field coil is in the opposite direction
as the current flow direction in its corresponding shunt-field coil,
in which case the field fluxes are subtractive. |
The current
flow direction in each series-field coil is in the opposite direction
as the current flow direction in its corresponding shunt-field coil,
in which case the field fluxes are additive. |
|
B |
Assuming
that a cumulatively compounded DC motor is fitted with interpoles and
compensating windings, normally how is the direction of rotation in
such a DC motor reversed? |
By reversing
the armature winding leads. |
By reversing
the armature-interpole-compensating winding leads as a unit. |
By reversing
the series field winding leads. |
By reversing
the shunt field winding leads. |
|
C |
If a motor
is direct-on-line started with the stator winding star connected, it
will only take a fraction of the starting current that it would take
if the windings were delta connected. What is that fraction? |
2/.3 |
1/ˆš3 |
1/3 |
1/2 |
|
C |
What is the
advantage of using a star delta starter? |
It is very
reliable and does not generate any surge current. |
It gives an
acceptable reduction in surge current without undue increase in run-up
time. |
It is the
most cost effective method of reduced voltage starting. |
The voltage
is initially increased and then stepped down to rated voltage
resulting in minimum heating of the coils. |
|
D |
What is the
advantage of using an auto-transformer starter? |
The starter
enables the voltage to be disconnected while changing over to rated
voltage. |
The voltage
is initially increased and then stepped down to rated voltage
resulting in minimum heating of the coils. |
It is
cheaper as compared to other starters. |
It gives an
acceptable reduction in surge current without undue increase in run-up
time. |
|
D |
After a
black out onboard and once ships power has been restored, the engine
room supply fans must be started manually. What characteristic of the
electrical circuit for the supply fans cause this requirement? |
The thermal
overload has tripped and must be reset. |
The circuit
for the supply fan is wired for low voltage release. |
The main breaker for the supply fan on the switchboard has tripped and
must be reset
manually. |
The circuit
for the supply fan is wired for low voltage protection. |
|
C |
You direct
the electrician to take quarterly insulation resistance reading of the
ship's critical motors. What additional directions would you give to
ensure accurate readings are taken that will allow for the logical
comparison of prior and current readings? |
Use a
different megohmmeter from previous tests. |
While using
a hand crank megohmmeter take a reading after 30 seconds of cranking
the handle. |
Correct the
readings to a reference temperature; reference temperature should be
recorded in prior readings history. |
While using
a hand crank megohmmeter take a reading after 3 minutes of cranking
the handle. |
|
A |
The design
Power Factor (PF) of a vessel's electrical system is generally 0.8
-0.9. The system's greatest load is inductive. One notices a slow,
gradual decrease, over time, in the PF, from normal/design. What can
one do on board to maintain the normal, design PF and thus maintain
electrical system's efficiency? |
Determine
that all induction motor driven pumps, fans, compressors, etc. are
operating at their design capacity and design electrical load. |
Add
capacitive load to major inductive power load consumers. |
Add
resistive load to major inductive power load consumers. |
Increase the
entire electrical system's frequency. |
|
B |
The
electrical officer is about to check the insulation resistance. When
advice should you give to him as to what temperature and or when he
should check the motor insulation?
|
Allow the
motor to cool down and check insulation. |
Testing
should be done at or near the motor temperature as the insulation
becomes leaky at high temperatures. . |
Check the
insulation when the motor is live. |
Insulation
resistance need not be tested. |
|
C |
When testing
the rotor of a synchronous motor for short circuits, a low voltage
source is applied across the rotor coils through the collector rings.
What would be the indication of a short-circuited coil? |
fluctuating
voltmeter reading, while the other coil readings are steady |
steady
voltmeter reading, while the other coil readings are fluctuating |
low or zero
voltage drop reading, while the other coils will have higher readings |
high voltage
drop reading, while the other coil readings will have an equal or
lower value |
|
A |
If a
three-phase induction motor malfunctions and drops to a single-phase
(one supply line open), what would be the result? |
the motor
will continue to run if it is not heavily loaded |
the motor
will immediately stop and can only be restarted at no load |
the motor
will immediately stop and not be able to be restarted |
more torque
will be developed |
|
A |
What would
be the most likely fault if a single-phase permanent split capacitor
induction motor fails to start? |
an open
start winding |
an open
centrifugal switch |
an open
start capacitor |
a closed
centrifugal switch |
|
C |
In testing a
three-phase delta-connected winding for an open circuit using an
ohmmeter, what must be done? |
measure the
voltage across the open connections while testing |
test each
phase with all connections intact |
if possible,
open the delta-connections to avoid shunting the phase being tested |
test the
windings as parallel groups to avoid short circuiting |
|
B |
As shown in
figure "A" of the illustration, with a digital multimeter set up as an
ohmmeter, what set of readings would be consistent with an open in
phase "B" of the single circuit, wye-connected stator windings as
shown? Illustration EL-0201 |
T1 to T2:
"OL ohms"; T2 to T3: "1.8 ohms"; T3 to T1: "1.8 ohms" |
T1 to T2:
"OL ohms"; T2 to T3: "OL ohms"; T3 to T1: "1.8 ohms" |
T1 to T2:
"1.8 ohms"; T2 to T3: "OL ohms"; T3 to T1: "OL ohms" |
T1 to T2:
"OL ohms"; T2 to T3: "1.8 ohms"; T3 to T1: "OL ohms" |
|
A |
As shown in
the illustrated diagnostic setup checking for a reversed field pole on
a ten-pole synchronous motor, if a rotor is being checked after
reassembly and the steel bolts repel each other as shown in the
illustration, what condition is indicated? Illustration EL-0205 |
Either coil
3 or coil 4 has a reversed polarity |
An
undetermined coil has reversed polarity |
Both coils 3
and coil 4 have the correct polarity |
All coils
have the correct polarity |
|
C |
What would
happen if the centrifugal switch or relay, for cutting out the
starting winding of a split-phase induction motor, failed to open
while the motor was in operation? |
The motor
would over speed. |
The motor
would run at a reduced speed. |
The winding
would burn out. |
A time delay
would stop the motor. |
|
D |
Ships
requiring rapid maneuvering response with a high degree of main
propeller shaft control are most often what type of drive system? |
Gas turbine
geared drive |
Steam
turbine geared drive |
Direct or
geared diesel drive |
Diesel-electric drive |
|
C |
What is one
major advantage of a diesel electric propulsion plant? |
less
maintenance |
lower fuel
consumption |
excellent
maneuverability |
low cost and
weight |
|
A |
Which of the
following is a disadvantage of electric drive propulsion systems? |
Propulsion
motors are required along with electrical power generation machinery. |
Main
propulsion power may also be directed to ships electrical service
distribution. |
The
propeller speed and direction of rotation are easily controllable. |
Location of
electric power generation machinery is flexible. |
|
A |
Which
statement is TRUE concerning electric propulsion drives? |
The
propeller speed and direction of rotation are easily controllable. |
Lower
transmission losses compared to other types of propulsion drives. |
Inability to
be utilized as a source of ships service power. |
Lack of
flexibility of arrangement between the prime mover and motor. |
|
C |
An electric
propulsion drive system in which the propulsion generator supplies
power to both the propulsion motor and ship service loads is referred
to as what type of system? |
a
multi-purpose system |
a dedicated
system |
an
integrated system |
a composite
system |
|
A |
Which of the
listed temperature measuring devices installed on a large
turbo-electric alternating current propulsion generator would be the
most reliable for monitoring generator temperatures to avoid premature
winding insulation failure? |
Temperature
sensors inserted in the stator slots for measuring stator winding
temperature. |
Temperature
sensors measuring the temperature of the cooling air associated with
the generator air cooler |
Temperature
sensors measuring the temperature of the cooling water associated with
the generator air cooler |
Current
transformers are the most reliable means of monitoring generator
temperatures |
|
D |
How is the
main shaft rotation on an AC diesel-electric propulsion vessel
normally reversed? |
reversing
the prime mover rotation |
decreasing
the generator frequency |
increasing
the generator frequency |
reversing
the phase sequence supplied to the motor |
|
A |
What is the
operating function of a cycloconverter (CCV) as a static power
converter used in electric propulsion motor drives? |
provides
adjustable frequency to power an ac propulsion drive motor |
provides
constant frequency output power to an ac propulsion drive motor |
converts dc
power to ac power in an ac propulsion motor |
converts ac
power to dc power in a dc propulsion drive system |
|
C |
The
propulsion motor most often utilized in an ac drive system operating
in the moderate to high power range is of what type? |
wound rotor
induction type |
squirrel
cage induction type |
synchronous
type with wound field |
split phase
induction type |
|
C |
What type of
electric propulsion system converter is shown in the illustration?
Illustration EL-0155 |
pulse width
modulation converter |
cycloconverter |
synchroconverter |
controlled
rectifier converter |
|
B |
As shown in
figure "A" of the illustration, the load-commutated inverter drive
illustrated has how many pulses? Illustration EL-0159 |
3 |
6 |
9 |
12 |
|
A |
As shown in
figure "B" of the illustration, what statement is true concerning
"regenerating" operation? Illustration EL-0162 |
by applying
torque in the opposite direction of rotation direction, the motor
briefly regenerates power back into the mains, which rapidly slows
down the motor |
by applying
torque in the same direction of rotation direction, the motor briefly
regenerates power back into the mains, which rapidly slows down the
motor |
by applying
torque in the opposite direction of rotation direction, the motor
briefly regenerates power back into the mains, which rapidly speeds up
the motor |
by applying
torque in the same direction of rotation direction, the motor briefly
regenerates power back into the mains, which rapidly speeds up the
motor |
|
C |
As shown in
the illustration, if the port propulsion motor field excitation
circuit experienced a failure, what individual component failure would
allow the use of the standby excitation transformer and standby field
controller to resume normal operation? Illustration EL-0164 |
port rotary
transformer |
port
rotating rectifier |
port field
controller |
port motor
field winding |
|
B |
A shown in
figure "A" of the illustrated propulsion motor variable speed drive,
what statement is true? Illustration EL-0140 |
both the
bridge rectifier and the controller inverter bridge are thyristor
controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
transistor controlled in terms of switching |
both the
bridge rectifier and the controller inverter bridge are transistor
controlled in terms of switching |
the bridge
rectifier is uncontrolled and the controller inverter bridge is
thyristor controlled in terms of switching |
|
B |
By what
common means is the speed of an AC propulsion motor on a
diesel-electric propulsion ship controlled? |
by
decreasing the motor voltage |
by varying
the input frequency of the voltage to the motor |
by
increasing the current to the motor |
by
increasing the motor voltage |
|
A |
While
standing an "at sea watch" onboard an AC diesel-electric drive ship
with a synchronous propulsion motor, you notice that the kwatt load is
at roughly 75% of capacity with a leading power factor less than 1.
Ideally what would be the character of the power factor associated
with the main power distribution including all motors? |
unity |
zero |
leading |
lagging |
|
C |
In a diesel
electric plant, raising the generator's field excitation current will
have what effect on the DC propulsion motor speed? |
affect
generator speed only |
decrease in
speed |
increase in
speed |
affect main
motor speed if done in conjunction with higher generator engine speeds |
|
A |
How is the
main propeller shaft rotation of a rectified DC diesel-electric drive
normally reversed? |
reversing
the field polarity in the DC motor |
reversing
the diesel engine rotation |
reversing
the field polarity in the AC generator |
reversing
the interpoles |
|
D |
What type of
motor is generally used in DC propulsion drive systems? |
series wound |
permanent
magnet |
differentially compounded |
shunt wound |
|
B |
What
equipment for modern SCR rectified DC propulsion drive systems is
usually included in the package? |
propulsion
generators which produce DC power that is converted to AC power for
the propulsion motor |
propulsion
generators which produce AC power that is converted to DC power for
the shunt wound DC propulsion motor |
propulsion
generators which produce AC power that is directly delivered to the
synchronous AC propulsion motor |
propulsion
generators which produce DC power that is directly delivered to the
series wound DC propulsion motor |
|
A |
What
statement is TRUE concerning the Azipod propulsion system? |
It is an
electric drive system where the propulsion motor is installed in a
submerged housing capable of swiveling. |
It is an
electric drive system in which the motor drives a controllable pitch
propeller (CPP). |
It is an
electric drive system using water jets. |
It is an
electric drive system that incorporates a DC motor. |
|
C |
Which of the
following statement is TRUE concerning Azipod propulsion systems? |
The pod
assembly swivels on a horizontal axis. |
The system
requires the need for a separate rudder. |
The system
integrates propulsion and steering into one function. |
The system
requires the use of a controllable pitch propeller. |
|
A |
In an azipod
propulsion system, how is three phase, frequency and voltage
controlled power delivered to the synchronous propulsion motor stator
windings? |
By the use
of slip rings and brushes. |
By rotary
transformer action. |
By direct
connection to the stator windings. |
By the use
of commutator bars and brushes. |
|
C |
In an azipod
propulsion system, how is direct current delivered to the synchronous
propulsion motor rotor for synchronous operation? |
By direct
connection to the rotor windings. |
By magneto
effect. |
By the use
of slip rings and brushes. |
By the use
of commutator bars and brushes. |
|
C |
In an azipod
propulsion system, how is the azipod unit itself rotated for the
purposes of directing the thrust in accordance with steering commands
from the bridge? |
The azipod
drive unit is rotated by means of a pneumatic steering unit. |
The azipod
drive unit is rotated by means of an electro-mechanical steering unit. |
The azipod
drive unit is rotated by means of a hydraulic steering unit. |
The azipod
drive unit is rotated by means of a synchronous transmission system. |
|
B |
It is
desired to add additional 120 VAC, 100 watt lighting fixtures in the
accommodations, port side fed from circuit #1 (1L110) as illustrated
in the lighting panel L110 of the illustration. According to 46 CFR
111.75-5, would be the maximum allowable additional lighting fixtures
that could be installed? Illustration EL-0013 |
1 fixture |
2 fixtures |
3 fixtures |
4 fixtures |
|
B |
According to
CFR 111.75-5, what would be the maximum amperage load on circuit #2
(2L110) of the illustrated lighting panel board L110 of the
illustration? Illustration EL-0013 |
3 amps |
12 amps |
15 amps |
16 amps |
|
D |
According to
46 CFR, Subchapter J (Electrical Engineering), which of the following
statements concerning battery installations is correct? |
Power and
lighting batteries must be of the lead-acid type only. |
When power
ventilation is required, the ventilation may be accomplished by a
ventilation system that serves other spaces. |
When power
ventilation is required, blower blades must be nonsparking and the
system must be interlocked with the battery charger to prevent
simultaneous operation. |
When power
ventilation is required, blower blades must be nonsparking and the
system must be interlocked with the battery charger to prevent charger
operation unless the ventilation fan is running. |
|
B |
You are in
the planning stages of replacing a battery charger, where an exact
duplicate of the charger to be replaced is not available. Obviously
the charger must be suitable for the battery to be charged. According
to 46 CFR, Subchapter J (Electrical Engineering), which of the
following is a true statement concerning battery chargers? |
Battery
chargers incorporating grounded autotransformers must NOT be used, and
if the charging voltage is less than 20% of the battery line voltage,
automatic protection against reversal current must be provided. |
Battery
chargers incorporating grounded autotransformers must NOT be used, and
if the charging voltage exceeds 20% of the battery line voltage,
automatic protection against reversal current must be provided. |
Battery
chargers incorporating grounded autotransformers must be used, and if
the charging voltage is less than 20% of the battery line voltage,
automatic protection against reversal current must be provided. |
Battery
chargers incorporating grounded autotransformers must be used, and if
the charging voltage exceeds 20% of the battery line voltage,
automatic protection against reversal current must be provided. |
|
C |
Suppose a
cargo vessel of 1600 gross tons or more is fitted with emergency
storage batteries for the purpose of supplying emergency lighting and
power. According to 46 CFR, Subchapter J (Electrical Engineering), the
capacity of the storage batteries is such that they should be able to
successfully power the emergency loads for a period of 18 hours.
Beginning with fully charged batteries, what is the minimum allowable
voltage of the batteries after the 18 hour discharge period assuming a
nominal voltage rating of 24 VDC and operating at rated capacity. |
16.0 VDC |
18.8 VDC |
21.1 VDC |
22.8 VDC |
|
B |
In
accordance with 46 CFR Part 112, a storage battery for an emergency
lighting and power system must have the capacity to accomplish which
of the following? |
open and
close all watertight doors in six consecutive cycles within a 20
second period |
close all
watertight doors twice and open them once |
open and
close all watertight doors in six consecutive cycles within a 45
second period |
open all
watertight doors four times and close them twice |
|
C |
Suppose a
cargo vessel of 1600 gross tons or more is fitted with emergency
storage batteries for the purpose of supplying emergency lighting and
power. According to 46 CFR, Subchapter J (Electrical Engineering), the
capacity of the storage batteries is such that they should be able to
successfully power the emergency loads for a period of 18 hours.
Beginning with fully charged batteries, what is the minimum allowable
percentage of the voltage rating of the batteries after the 18 hour
discharge period assuming a nominal voltage rating of 24 VDC and
operating at rated capacity. |
75 (%) |
80 (%) |
88 (%) |
95 (%) |
|
B |
In
accordance with 46 CFR, Subchapter J (Electrical Engineering), each
diesel engine driven generator prime mover must have an over speed
device, independent of the normal operating governor. If in testing
the over speed device, what should be the trip point setting in terms
of rated speed? |
not to
exceed 10% above rated speed |
not to
exceed 15% above rated speed |
not to
exceed 20% above rated speed |
not to
exceed 25% above rated speed |
|
D |
You are in
the planning stages of setting the instantaneous trip of a ship's
service generator circuit breaker. According to 46 CFR, Subchapter J
(Electrical Engineering), what statement is true regarding the
criteria for the instantaneous trip set point, assuming the generator
is capable of being paralleled? |
The trip
point should be set exactly equal to the maximum asymmetrical short
circuit current available. |
The trip
point should be set below but as close as practical to the maximum
asymmetrical short circuit current available. |
The trip
point should be set considerably above the maximum asymmetrical short
circuit current available. |
The trip
point should be set above but as close as practical to the maximum
asymmetrical short circuit current available. |
|
B |
There are
very specific rules that govern the testing of generators found in the
appropriate publication incorporated by reference. According to 46
CFR, Subchapter J (Electrical Engineering), which agency publishes the
rules for the construction and testing of generators __________. |
ASME |
American
Bureau of Shipping |
manufacturer |
Underwriter's Laboratories, Inc. |
|
B |
You are in
the planning stages of setting the longtime over current trip of a
ship's service generator circuit breaker. According to 46 CFR,
Subchapter J (Electrical Engineering), what statement is true
regarding the criteria for the longtime over current trip set point,
assuming the generator is capable of being paralleled?
o |
The trip
point should not be less than 100% of the generator rating for a
continuous rated machine. |
The trip
point should not be larger than 115% of the generator rating for a
continuous rated machine. |
The trip
point should not be larger than 100% of the generator rating for a
continuous rated machine. |
The trip
point should not be less than 115% of the generator rating for a
continuous rated machine. |
|
A |
Assuming
that a ship's service generator is directly coupled to the prime
mover, what condition must cause a prime mover to automatically shut
down? |
Low
generator bearing lubricating oil pressure. |
High
generator cooling air temperature. |
Low
generator output frequency. |
High
generator power factor. |
|
A |
Emergency
generators are required to automatically start upon a loss of normal
supply voltage, according to 46 CFR, Subchapter J (Electrical
Engineering). In conducting a test of the emergency generator
automatic transfer of load function, if the normal system supply
voltage is 450 VAC, to what value would the emergency generator output
voltage have to rise to trigger the automatic transfer of emergency
loads to the emergency generator? |
The voltage
would have to rise to a value between from 382.5 VAC to 427.5 VAC. |
The voltage
would have to rise to 382.5 VAC. |
The voltage
would have to rise to 427.5 VAC. |
The voltage
would have to rise to a value ranging from between 405 VAC to 450 VAC. |
|
B |
Emergency
generators are required to automatically start upon a loss of normal
supply voltage, according to 46 CFR, Subchapter J (Electrical
Engineering). In conducting a test of the emergency generator
automatic transfer of load function, if the normal system supply
voltage is 480 VAC, to what value would the normal source output
voltage have to rise to trigger the automatic transfer of emergency
loads back to the normal power source? |
It would
have to rise to a value between from 440 VAC to 460 VAC. |
It would
have to rise to a value between from 408 VAC to 456 VAC. |
It would
have to rise to 456 VAC. |
It would
have to rise to 408 VAC. |
|
B |
According to
46 CFR, Subchapter J (Electrical Engineering), which of the following
starting aids is the ONLY method allowed to ease the starting of
emergency diesel generator engines? |
Ether
injection systems |
Thermostatically controlled electric jacket water heaters |
Electric,
steam, or hot water heated lube oil heaters |
Electric air
intake heaters |
|
B |
According to
46 CFR, Subchapter J (Electrical Engineering), in response to a loss
of normal power or a simulated test, when will the emergency loads
automatically be transferred to the emergency diesel generator? |
as soon as
it is started |
when the
potential from the emergency generator reaches 85 to 95 percent of its
normal value |
when the
electric potential of the ship's service generators drops to 85 to 95
percent of the normal value |
when the
electric potential of the ship's service generators drops 15 to 40
percent below normal value |
|
B |
According to
46 CFR, Subchapter J (Electrical Engineering), emergency diesel engine
starting systems are required to have sufficient capacity to provide
power for at least how many consecutive starts? |
3 |
6 |
9 |
12 |
|
B |
According to
46 CFR, Subchapter J (Electrical Engineering), when considering
replacement, instrument and control wiring in a switchboard is to be
of what minimum size? |
12 AWG |
14 AWG |
16 AWG |
18 AWG |
|
D |
According to
46 CFR, Subchapter J (Electrical engineering), regulations prohibit
the use of portable electric cord or fixture wire aboard ship if that
wire or cord is smaller than what size? |
12 AWG |
14 AWG |
16 AWG |
18 AWG |
|
C |
According to
46 CFR, Subchapter J (Electrical Engineering), what statement is true
concerning the use of twist-on connectors? |
Twist-on
connectors may be used to facilitate a conductor splice. |
Twist-on
connectors may be used for making joints in cables. |
Twist-on
connectors may be used in enclosures as long as the insulating cap can
be secured to prevent loosening due to vibration. |
Twist-on
connectors may be used to extend the length of a circuit. |
|
A |
According to
CFR, Subchapter J (Electrical Engineering), which of the following
statements is true concerning flexible electric cord and cable used
aboard ship? |
No. 12 AWG
cable or cord may be spliced for repairs if made in compliance with
CFR 111.60
19.
o |
No. 14 AWG
cable or cord may be spliced for repairs if made in compliance with
CFR 111.60
19.
o |
No. 16 AWG
cable or cord may be spliced for repairs if made in compliance with
CFR 111.60
19. |
No. 18 AWG
cable or cord may be spliced for repairs if made in compliance with
CFR 111.60
19. |
|
B |
Electrical
wire in general, when used aboard vessels must meet minimum
requirements. Which of the following statements is/are correct? |
Wire need
not be in an enclosure nor component insulated? |
Wire must be
of the stranded copper type. |
Each wire
must be 14 AWG or larger, regardless of locations and use. |
Wire must be
of the solid copper type. |
|
B |
You are in
the planning stages of making up a portable cable to be used for
transmitting power from a battery charger on a ship to a charging
receptacle on a lifeboat. According to 46 CFR, Subchapter J
(Electrical Engineering), which of the following statements is true
regarding the transmitting of power between receptacles?
o |
The plug on
the end of the cord that may be energized when unplugged from the
receptacle must be male. |
The plug on
the end of the cord that may be energized when unplugged from the
receptacle must be female. |
The plugs on
both ends of the cord must be male. |
Regulations
do not allow transmitting power between receptacles under any
circumstances. |
|
C |
According to
46 CFR, Subchapter J (Electrical Engineering) regulations, receptacle
outlets at or above what voltage are required to have grounding poles? |
24 volts |
48 volts |
100 volts |
220 volts |
|
A |
According to
46 CFR, Subchapter J (Electrical Engineering) regulations, what is the
minimum conductor size associated with a 25 or 30 ampere lighting
branch circuit supplying a non-switched cargo hold light fixture? |
10 gauge |
12 gauge |
14 gauge |
16 gauge |
|
A |
At a minimum
threshold, how many milliamps of current through the body produces a
painful sensation that most people would perceive as an electric
shock? |
3 to 7 mA |
10 to 16 mA |
30 mA |
100 mA for
2.5 sec. |
|
B |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would be unable to let go of the energized
electrical conductor due to involuntary muscular contraction? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
C |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would experience respiratory paralysis and
be unable to breathe while still in contact with the energized
conductor? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
D |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would suffer ventricular fibrillation and
could only be resuscitated with a ventricular defibrillator? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
B |
With all
other factors considered equal (such as voltage, conducting path
through the body and the duration of contact), contact with an
energized electrical system conductor of which system type would
produce the most damaging effect? |
DC systems |
60 Hz AC
systems |
10 kHz AC
systems |
All the
above systems would be equally as damaging |
|
B |
Before
electrical work can be safely undertaken, the equipment must be
de-energized, locked and tagged out, and verification must be made
that the circuit is actually dead. What testing device is most certain
to reliably verify that a circuit is actually dead? |
a
non-contact voltage tester |
an
auto-ranging digital multimeter |
a solenoid
type voltage tester |
a non-auto
ranging digital multimeter |
|
A |
Which of the
following devices would be forbidden to use as a primary means of
electrical isolation? |
start/stop
pushbutton station |
non-fused
disconnect switch |
circuit
breaker |
fused
disconnect switch |
|
B |
Which of the
following voltage testers would be associated with high quality, be
safe to use, and minimize the electric shock hazard? |
a voltage
tester with a low input voltage and a lower voltage rating than any
expected measured voltage |
a voltage
tester with a high input impedance and a voltage rating higher than
any expected measured voltages |
a voltage
tester with a low input impedance and a higher voltage rating than any
expected measured voltages |
a voltage
tester with a high input impedance and a lower voltage rating than any
expected measured voltages |
|
C |
What is the
primary means by which an electrical maintenance worker is protected
from electrical hazards while performing work on an electrical
circuit? |
using the
appropriate personal protective equipment |
shutting
down the necessary equipment |
performing a
lockout/tagout procedure |
posting of
safety warning signs |
|
B |
After prior
isolation and lockout/tagout procedures are performed, which
electrical device requires discharging any stored electrical energy
before any work may safely begin? |
resistor
bank |
capacitor |
potential
transformer |
choke coil |
|
D |
What is the
primary means by which an electrical maintenance worker is protected
from electrical hazards while performing work on an electrical
circuit? |
shutting
down the necessary equipment |
using the
appropriate personal protective equipment |
posting of
safety warning signs |
performing a
lockout/tagout procedure |
|
A |
Which of the
following voltage testers would be associated with high quality, be
safe to use, and minimize the electric shock hazard? |
a voltage
tester with a high input impedance and a voltage rating higher than
any expected measured voltages |
a voltage
tester with a low input impedance and a higher voltage rating than any
expected measured voltages |
a voltage
tester with a low input voltage and a lower voltage rating than any
expected measured voltage |
a voltage
tester with a high input impedance and a lower voltage rating than any
expected measured voltages |
|
D |
Which of the
following devices would be forbidden to use as a primary means of
electrical isolation? |
circuit
breaker |
fused
disconnect switch |
non-fused
disconnect switch |
start/stop
pushbutton station |
|
A |
Before
electrical work can be safely undertaken, the equipment must be
de-energized, locked and tagged out, and verification must be made
that the circuit is actually dead. What testing device is most certain
to reliably verify that a circuit is actually dead? |
an
auto-ranging digital multimeter |
a solenoid
type voltage tester |
a non-auto
ranging digital multimeter |
a
non-contact voltage tester |
|
B |
With all
other factors considered equal (such as voltage, conducting path
through the body and the duration of contact), contact with an
energized electrical system conductor of which system type would
produce the most damaging effect? |
DC systems |
60 Hz AC
systems |
10 kHz AC
systems |
All the
above systems would be equally as damaging |
|
D |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would suffer ventricular fibrillation and
could only be resuscitated with a ventricular defibrillator? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
C |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would experience respiratory paralysis and
be unable to breathe while still in contact with the energized
conductor? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
B |
At a minimum
threshold, how many milliamps of current through the body produces a
condition where most people would be unable to let go of the energized
electrical conductor due to involuntary muscular contraction? |
3 to 7 mA |
10 to 16 mA |
30 mA |
75 mA for 5
sec. |
|
B |
After prior
isolation and lockout/tagout procedures are performed, which
electrical device requires discharging any stored electrical energy
before any work may safely begin? |
potential
transformer |
capacitor |
resistor
bank |
choke coil |
|
A |
At a minimum
threshold, how many milliamps of current through the body produces a
painful sensation that most people would perceive as an electric
shock? |
3 to 7 mA |
10 to 16 mA |
30 mA |
100 mA for
2.5 sec. |
|
C |
An
accidental path of low resistance bypassing the intended path and
allowing passage of an abnormally high amount of current is known as
what? |
open circuit |
polarized
ground |
short
circuit |
ground
reference point |
|
B |
How may the
unit "hertz" be best described? |
revolutions
per minute |
cycles per
second |
coulombs per
second |
revolutions
per second |
|
D |
In the flow
of one cycle of single phase alternating current past any given point
in a circuit, how many times will the current peak to a maximum? |
three times |
four times |
one time |
two times |
|
B |
The root
mean square (RMS) value of a sine-wave current may also be expressed
as what value? |
instantaneous value |
effective
value |
maximum
value |
average
value |
|
A |
What will
happen to an electrical coil when the direct current flowing through
the coil is increasing? |
the
increasing current produces a voltage in opposition to the applied
voltage |
the
increasing current reduces the power consumed |
the
increasing current reduces the amount of flux produced |
the
increasing current changes the coil's impedance |
|
C |
For the
purpose of calculating apparent power, which of the following
procedures should be used to determine the total load current of a
three-phase, delta wound, AC generator? |
Divide the
total amperage in all phases by three. |
Divide the
total amperage in all phases by the square root of three. |
Multiply the
amperage in one phase by the square root of three. |
Multiply the
amperage in one phase by three. |
|
C |
AC circuits
can possess characteristics of resistance, inductance, and
capacitance. In terms of units of measure, how is the capacitive
reactance of the circuit expressed? |
farads |
mhos |
ohms |
henrys |
|
A |
What is the
opposition to the establishment of magnetic lines of force in a
magnetic circuit called? |
reluctance |
inductance |
resistance |
impedance |
|
D |
In terms of
load type, in what type of alternating current circuit will the
voltage always lead the current? |
capacitive
circuit |
resistive
circuit |
resistive-capacitive circuit |
inductive
circuit |
|
D |
If the
voltage and the current developed in an AC circuit reach their peak
values at the same time (with a phase angle difference of zero), what
is the power factor considered to be? |
lagging |
infinity |
leading |
unity (1.0) |
|
C |
In a series
circuit, which value will remain unchanged at all places in the
circuit? |
Inductance |
Voltage |
Current |
Resistance |
|
A |
Which of the
following statements is correct for the illustrated circuit in figure
"B"? Illustration EL-0020 |
R1', 'R2',
and 'R3' are connected in series. |
The total
resistance equals 1/R1 + 1/R2 + 1/R3. |
R1', 'R2',
and 'R3' are connected in parallel. |
The voltages
measured across 'R1', 'R2', and 'R3' are equal. |
|
D |
In a series
circuit what is the total applied voltage equal to? |
the total
current divided by the total resistance |
the sum of
the individual currents multiplied by the number of resistors |
the total
resistance divided by the total current |
the sum of
the individual voltage drops |
|
A |
Referring to
figure "B" of the illustration, what statement is true? Illustration
EL-0020 |
The current
drawn by the circuit will be inversely proportional to the total
resistance of the entire circuit. |
If the
resistance values of the individual resistors are uniquely different,
each resistor will have a uniquely different current draw. |
The current
drawn by the circuit will be directly proportional to the total
resistance of the entire circuit. |
The current
drawn by an individual resistor will be proportional to the resistance
of that resistor. |
|
C |
Referring to
figure "B" of the illustration, what statement is true? Illustration
EL-0020 |
The order of
resistors connected in the series string has no impact on the total
resistance. The total resistance of the circuit will be less than any
one of the individual resistances. |
The order of
resistors connected in the series string has an impact on the total
resistance. If the largest resistance is last in the circuit, the
total resistance will be more than if it is not. |
The order of
resistors connected in the series string has no impact on the total
resistance. The sum of the resistances is the total resistance of the
circuit. |
The order of
resistors connected in the series string has an impact on the total
resistance. If the largest resistance is first in the circuit, the
total resistance will be more than if it is not. |
|
D |
Four lamps
are connected in series in a single circuit. If one of the lamp burns
out, what will happen to the other lamps? |
become
brighter |
become
dimmer |
burn with
their original intensities |
all go out |
|
A |
Which of the
electrical properties listed will always be the same across each
component in a parallel circuit? |
Voltage |
Resistance |
Current |
Impedance |
|
A |
Which of the
following statements concerning a circuit with parallel connected
resistors is correct? |
The voltage
drop across each resistor is the same. |
The total
current flow equals the reciprocal of the sum of the individual
currents. |
The total
voltage equals the sum of the individual voltages across each
resistance. |
The total
resistance equals the sum of the individual resistances. |
|
C |
What
statement is true concerning the total resistance of a parallel
circuit? |
The total
resistance is equal to the sum of the individual branch resistances
divided by the number of branches. |
The total
resistance is larger than that of the branch with the greatest
resistance. |
The total
resistance is smaller than that of the branch with the lowest
resistance. |
The total
resistance is equal to the sum of the individual branch resistances. |
|
A |
Which of the
following statements is true concerning circuits with parallel
connected resistances? |
The total
current flow equals the sum of the individual currents. |
The total
voltage equals the sum of the individual voltages across each
resistance. |
The total
current flow equals the reciprocal of the sum of the individual
currents. |
The total
resistance equals the sum of the individual resistance. |
|
C |
What
statement is true concerning the electrical diagram shown in figure
"B" of the illustration? Illustration EL-0019 |
The voltages
measured across 'R1', 'R2' and 'R3' will be different if 'R1', 'R2'
and 'R3' have different values. |
The total
resistance equals R1 + R2 + R3. |
R1', 'R2',
and 'R3' are connected in parallel. |
R1', 'R2',
and 'R3' are connected is series. |
|
C |
Four lamps
are connected in parallel in a single circuit. If one of the lamp
burns out, what will happen to the other lamps? |
become
brighter |
all go out |
burn with
their original intensities |
become
dimmer |
|
D |
What will
happen to the total circuit resistance when additional parallel
circuits are added to a circuit? |
it will
increase, causing a decrease in the line voltage |
it will
decrease, causing an increase in the line voltage |
it will
increase, causing a drop in the total load current |
it will
decrease, causing an increase in the total load current |
|
D |
As shown in
figure "A" of the illustration, with the switch closed what statement
is true if "R1" and "R2" have unequal resistance values? Illustration
EL-0019 |
The energy
dissipated in 'R1' will be the same as the energy dissipated in 'R2'. |
The voltage
drop across 'R1' will not be equal to the voltage drop across 'R2'. |
The current
flow through 'R1' will equal the current flow through 'R2'. |
The current
flow through 'R1' will differ from the current flow through 'R2'. |
|
B |
Which
statement is true concerning the total power consumed in a parallel
circuit? |
The total
power is always less than the power consumed by the smallest load. |
The total
power is equal to the sum of the powers consumed by each individual
load. |
The total
power is never more than the power consumed by the largest load. |
The total
power is the sum of the powers consumed by each load (resistor)
divided by the number of loads. |
|
C |
In a simple
DC circuit, the resistance is held constant while the applied voltage
is halved. What will be the effect on the current flow as compared to
the original current? |
be divided
by four |
remain the
same |
be divided
by two |
double |
|
D |
In a 60 Hz
AC system, what is the duration in seconds for one complete cycle? |
60 seconds |
6 seconds |
1 second |
.016 of a
second |
|
D |
How is the
power dissipated as heat in a direct current circuit calculated? |
P divided by
R |
E divided by
I |
I times R
divided by T |
I squared
times R |
|
B |
An
electrical component is connected across a 120 volt 60 hertz AC
supply. What is the current drawn by the component if the impedance is
200 ohms? |
0.01 amperes |
0.60 amperes |
1.67 amperes |
100 amperes |
|
D |
A 125 volt
DC motor is rated at 10 kW. What is the current rating of the motor? |
4.6 amps |
8.0 amps |
46.2 amps |
80 amps |
|
D |
What is the
total resistance of figure "B" of the illustrated circuit if the
resistance of R1 is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms?
Illustration EL-0020 |
0.5 ohms |
1.28 ohms |
1.5 ohms |
12 ohms |
|
C |
What is the
total resistance of the electrical circuit illustrated in figure "B"
if the resistance of R1 is 2 ohms, R2 is 4 ohms, and R3 is 4 ohms and
the battery voltage is 6 volts? Illustration EL-0019 |
0.01 ohms |
0.10 ohms |
1.00 ohms |
10.00 ohms |
|
C |
In the
illustration, 1, 2, 3 and 4 are 12 volt batteries. What will be the
nominal voltage as read by a voltmeter across the output of the
battery bank? Illustration EL-0107 |
6 volts |
12 volts |
24 volts |
48 volts |
|
C |
An AC
generator produces 60 Hz at 1800 RPM. If the generator speed is
increased to 1830 RPM, what will happen to the frequency in Hz? |
decrease to
59 Hz |
remain at 60
Hz |
increase to
61 Hz |
increase to
63 Hz |
|
D |
If the
supply voltage is 220 volts 60 Hz, what is the operating voltage of
the motor controller control circuit illustrated in figure A of the
illustration? Illustration EL-0011 |
110 volts DC |
110 volts AC |
220 volts DC |
220 volts AC |
|
A |
In the
schematic of the electrical circuit shown in figure "A" of the
illustration, what is the value of the total capacitance, when
compared to the value of equal individual capacitors? Illustration
EL-0039 |
one half |
one fourth |
quadruple |
double |
|
B |
An AC
circuit has a capacitive reactance of 30 ohms in addition to an
inductive reactance of 40 ohms connected in series. What is the total
reactance of the circuit? |
8.37 ohms |
10.00 ohms |
50.00 ohms |
70.00 ohms |
|
C |
In figure
"A" of the illustration, 12 volts is applied to the circuit where the
resistance of R1 is 10 ohms and R2 is 10 ohms. what is the voltage
across R2 when the switch is closed? Illustration EL-0020 |
1.2 volts |
2 volts |
6 volts |
12 volts |
|
A |
What will be
the total current in figure "B" of the illustrated circuit with the
switch closed if the applied voltage is 24 volts and the resistance of
R1 is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms, respectively?
Illustration EL-0020 |
2 amps |
6 amps |
8 amps |
10 amps |
|
C |
As shown in
figure "A" of the illustration, what would be the circuit impedance if
the capacitive reactance is 10 ohms and the resistance is 10 ohms?
Illustration EL-0109 |
4.47 ohms |
6.32 ohms |
14.14 ohms |
20 ohms |
|
D |
Two 100 watt
light bulbs rated at 100 volts are connected in parallel across a 100
volt power supply. What will be the total power consumed by the two
bulbs? |
50 watts |
66.7 watts |
100 watts |
200 watts |
|
B |
If a circuit
has resistances of 5, 10, and 20 ohms connected in parallel, what is
the combined total resistance of the circuit? |
1.5 ohms |
2.9 ohms |
17.5 ohms |
35.0 ohms |
|
C |
In the
schematic of the electrical circuit shown in figure "A" of the
illustration, what is the value of the total capacitance, when
compared to the value of equal individual capacitors? Illustration
EL-0038 |
Squared |
Equal |
Double |
Half |
|
D |
What would
be the total capacitance of the circuit illustrated in figure "A" if
the value of capacitor C1 was 100 microfarads and capacitor C2 was 200
microfarads? Illustration EL-0038 |
66.6
microfarads |
150
microfarads |
166.6
microfarads |
300
microfarads |
|
A |
What would
be the total current in figure "A" of the circuit illustrated if the
value of capacitor C1 was 100 microfarads, capacitor C2 was 200
microfarads and the power supply was 240 volts at 60 Hz? Illustration
EL-0038 |
27 amps |
37 amps |
47 amps |
57 amps |
|
A |
What would
be the capacitive reactance of the circuit shown in figure "A" of the
illustration if the capacitance of C1 was 100 microfarads, the
capacitance of C2 was 200 microfarads and the frequency of the source
was 60 cycles per second (Hz)? Illustration EL-0038 |
8.8 ohms |
17.7 ohms |
39.8 ohms |
79.6 ohms |
|
A |
What is the
current flowing through R3 in figure "B" of the illustrated circuit
when the switch is closed if the battery voltage is 12 VDC and
resistance of R1 is 2 ohms, R2 is 3 ohms, and R3 is 6 ohms,
respectively? Illustration EL-0019 |
2 amps |
4 amps |
6 amps |
12 amps |
|
B |
What would
be the voltage drop across the parallel branches of the circuit shown
in figure "B" of the illustration if the source voltage is 30 volts,
the resistance for R1 is 10 ohms, the resistance for R2 is 10 ohms and
the resistance for R3 is 10 ohms? Illustration EL-0032 |
5 volts |
10 volts |
20 volts |
30 volts |
|
D |
What would
be the voltage drop across the series string of the circuit shown in
figure "A" of the illustration if the source voltage is 30 volts, the
resistance for R1 is 10 ohms, the resistance for R2 is 10 ohms and the
resistance for R3 is 10 ohms? Illustration EL-0032 |
5 volts |
10 volts |
20 volts |
30 volts |
|
D |
What would
be the total current draw of the circuit as shown in figure "A" of the
illustration if the source voltage is 24 volts, the resistance for R1
is 12 ohms, the resistance for R2 is 24 ohms, and the resistance for
R3 is 36 ohms? Illustration EL-0032 |
0.33 amperes |
0.75 amperes |
1.25 amperes |
1.33 amperes |
|
C |
What would
the total power consumed by the circuit as shown in figure "A" of the
illustration if the source voltage is 12 volts, the resistance for R1
is 470 ohms, the resistance of R2 is 330 ohms, and the resistance of
R3 is 800 ohms? Illustration EL-0032 |
90
milliwatts |
180
milliwatts |
360
milliwatts |
720
milliwatts |
|
C |
What would
the total power consumed by the circuit as shown in figure "B" of the
illustration if the source voltage is 12 volts, the resistance for R1
is 470 ohms, the resistance of R2 is 800 ohms, and the resistance of
R3 is 330 ohms? Illustration EL-0032 |
57.5
milliwatts |
115
milliwatts |
230
milliwatts |
460
milliwatts |
|
A |
The turns
ratio of the tapped step down transformer shown in figure "C" of the
illustration is four to one and all taps are equally spaced. If 440
volts were applied between 'H1' and 'H4', what would appear across
'X1' and 'X4'? Illustration EL-0082 |
110 volts |
220 volts |
440 volts |
1760 volts |
|
A |
The turns
ratio of the tapped step down transformer shown in figure "C" of the
illustration is four to one and all taps are evenly spaced. If 120
volts were applied to terminals 'H1' and 'H3', what would appear at
'X1' and 'X2'? Illustration EL-0082 |
15 volts |
30 volts |
480 volts |
960 volts |
|
B |
In figure
"1" of the diagram shown in the illustration, the three phase step
down power transformer has a turns ratio of four to one. If a
three-phase 440 volt supply is connected to terminals "A1-B1-C1", what
voltage should develop across terminals "A2-B2-C2"? Illustration
EL-0084 |
64 volts |
110 volts |
190 volts |
762 volts |
|
B |
In figure
"2" of the diagram shown in the illustration, the three phase step
down power transformer has a turns ratio of four to one. If a
three-phase 480 volt supply is connected to terminals "A1-B1-C1", what
voltage should develop across terminals "A2-B2-C2"? Illustration
EL-0084 |
69 volts |
120 volts |
208 volts |
277 volts |
|
C |
In figure
"4" of the diagram in the illustration, the three phase step down
power transformer has a turns ratio of five to one. If a three-phase
4160 volt supply is connected to terminals "A1-B1-B2", what voltage
should develop across terminals "A2-B2-C2"? Illustration EL-0084 |
240 volts |
415 volts |
480 volts |
832 volts |
|
C |
A simple,
untapped, single-phase 480/120 VAC step-down control transformer is
rated at 600VA at 60 Hz. Neglecting power factor, what is the rated
secondary load current? |
1.25 amperes |
4 amperes |
5 amperes |
10 amperes |
|
B |
What would
be the synchronous speed of an eight-pole three-phase squirrel-cage
induction motor operating at 60 Hz? |
875 rpm |
900 rpm |
1725 rpm |
1800 rpm |
|
B |
What would
be the synchronous speed of a 24-pole three-phase synchronous motor
operating at 20 Hz? |
50 rpm |
100 rpm |
200 rpm |
240 rpm |
|
A |
What would
be the actual rotor speed for a 4-pole three-phase squirrel-cage
induction motor operating at 60 Hz if the rotor slip is 3%? |
1746 rpm |
1793 rpm |
1800 rpm |
1854 rpm |
|
B |
If a 12-pole
three-phase synchronous alternator is operating at 590 rpm, what will
be its output frequency? |
58 Hz |
59 Hz |
60 Hz |
61 Hz |
|
B |
A six-pole
three-phase squirrel-cage induction motor operating at 60 Hz is
running at 1155 rpm. What is the percentage slip in this case? |
3 (%) |
3.75 (%) |
4.25 (%) |
5 (%) |
|
D |
What will be
the resulting total current if a voltage of 125 VDC is applied to the
loads of the circuit in figure "A" of the illustration where the
resistance of R1 is 12 ohms, and R2 is 115 ohms? Illustration EL-0019 |
115 amps |
12.5 amps |
125 amps |
11.5 amps |
|
A |
What would
be the total current in figure "A" of the circuit illustrated if the
value of capacitor C1 was 100 microfarads, capacitor C2 was 200
microfarads and the power supply was 240 volts at 60 Hz? Illustration
EL-0038 |
27 amps |
37 amps |
47 amps |
57 amps |
|
B |
What would
be the terminal voltage and ampere-hour capacity of the battery bank
illustrated if each battery was rated at 75 ampere-hours and 12 volts?
Illustration EL-0107 |
12 volts and
150 ampere-hours |
24 volts and
150 ampere-hours |
48 volts and
300 ampere-hours |
24 volts and
75 ampere-hours |
|
D |
In figure
"B" of the illustrated circuit, if the resistance of R1 is 10 ohms, R2
is 10 ohms, and R3 is 10 ohms, what is the total resistance?
Illustration EL-0032 |
20 ohms |
25 ohms |
30 ohms |
15 ohms |
|
B |
A 440/110 V
single phase transformer supplies a load of 5 kW at 0.8 power factor
load. What will be its secondary current ignoring transformer power
losses? |
14.2 A |
56.82 A |
45.45 A |
11.36 A |
|
C |
A 440/110 V
single phase transformer supplies a load of 5 kW at 0.8 power factor
load. What will be its primary current? |
45.45 A |
56.82 A |
14.2 A |
11.36 A |
|
B |
What is the
maximum current allowed to be drawn from the secondary of a 2 kVA
step-down transformer with a turns ratio of four to one if connected
across a 440 volt line? |
22.7 amps |
18.1 amps |
1.1 amps |
4.5 amps |
|
C |
The turns
ratio of the step down transformer with dual voltage secondary shown
in figure "B" of the illustration is two to one (total). If 220 volts
were applied to terminals 'H1' and 'H2', what would be measured across
'X3' and 'X4'? Illustration EL-0082 |
880 volts |
110 volts |
55 volts |
440 volts |
|
A |
As shown in
figure "B" of the illustration, if the source voltage at the branch
circuit breaker is 220 VAC, what would be the applied voltage to the
load? Illustration EL-0083 |
55 volts |
110 volts |
165 volts |
220 volts |
|
C |
If a 6-pole
motor is supplied at 60 Hz and runs with a slip of 5%, what is the
actual rotor speed? |
1200 rpm |
1240 rpm |
1140 rpm |
1260 rpm |
|
C |
An
electrical component is connected across a 120 volt 60 hertz AC
supply. What is the current drawn by the component if the impedance is
200 ohms? |
100 amperes |
1.67 amperes |
0.60 amperes |
0.01 amperes |
|
C |
The apparent
power supplied to a motor is six kilovolt amps at 120 volts. What is
the impedance of the motor? |
0.50 ohms |
0.05 ohms |
2.40 ohms |
24.00 ohms |
|
C |
An AC motor
is started and produces 25 horsepower when running at rated speed and
load. Neglecting power factor considerations, how much will the kW
meter reading increase for the sole generator providing power? |
37.65 kW |
30.65 kW |
18.65 kW |
25.65 kW |
|
D |
What will be
the resulting current when a voltage of 12 VDC is applied to a
capacitance of 470 microfarads in figure "C" of the illustrated
circuit after the capacitor has had ample time to fully charge?
Illustration EL-0018 |
5.64 amps |
25.5 amps |
0.0255 amps |
0.0 amps |
|
A |
If the
values of "C1" and "R1" shown in the illustration were 1 microfarad
and 3 megohms respectively, which of the listed intervals of time
would equal one "time constant"? Illustration EL-0086 |
3 seconds |
0.33 second |
6 seconds |
15 seconds |
|
A |
If coil
'R1-R2-R3' on the transmitter in figure "C" shown in the illustration
is turned 30 degrees clockwise, how will the corresponding coils
'R1-R2-R3' on the receivers (indicators) respond? Illustration EL-0092 |
torque will
cause them to align to the same position |
receive a
lower voltage depending on the turns ratio |
ring at the
receiving station until the turning stops |
receive a
higher voltage depending on the turns ratio |
|
A |
In actual
applications, electrical connections associated with 'R1, R2 and R3'
of the transmitter to 'R1, R2, and R3' of the indicators shown in
figure "C" of the illustration are made by what means? Illustration
EL-0092 |
slip rings
and brushes |
spliced and
taped connections |
soldered
contacts |
solderless
crimp-on connectors |
|
B |
What
controls rudder movement when the Operation Selector Switch shown in
figure "A" of the illustration is in the "Controller" position?
Illustration EL-0097 |
ship's
steering wheel |
non-follow-up controller |
rate of turn
signal |
gyro-compass |
|
D |
As shown in
figure "A" of the illustration, fine adjustments such as "rate of turn
signal" have no effect on steering stand operation when the 'operation
selector switch' is in what position? Illustration EL-0097 |
DIFF |
HAND |
GYRO |
NFU |
|
D |
When power
is restored after a complete power failure, how will the steering gear
pump motor which was on-line respond? |
it will have
to be restarted manually |
it will have
to be reset manually |
it will trip
its overload relays |
it will
restart automatically |
|
A |
What
functionality do the 'MS 1' contacts of the master switch shown in the
illustration provide? Illustration EL-0102 |
low voltage
protection |
high power
factor correction |
overload
protection |
low voltage
release |
|
A |
What is the
functional purpose of the 'LSH' contacts for the hoist controller
circuit shown in the illustration? Illustration EL-0102 |
it is a
limit switch which automatically stops the winch drum rotation in the
hoist direction before the hoist block is able to strike the boom |
it is a
limit switch which illuminates a warning light to warn the winch
operator when the hoist block is approaching the boom |
it is a
limit switch which illuminates a warning light to warn the winch
operator when the cable has only a few wraps on the drum while paying
out |
it is a
limit switch which automatically stops the winch drum rotation in the
lower direction before all the cable is payed out insuring that a few
wraps remain on the drum |
|
A |
As shown in
the illustration, what is the functional purpose of the normally
closed and normally open auxiliary contacts of the hoist and lower
contactors respectively? Illustration EL-0102 |
the normally
closed hoist and lower contactor auxiliary contacts are interlock
contacts preventing simultaneous pulling in both the hoist and lower
contactors and the normally open contacts extend control power to the
speed control circuits |
the normally
closed and normally open hoist and lower contactor auxiliary contacts
are interlock contacts preventing simultaneous pulling in both the
hoist and lower contactors |
the normally
open hoist and lower contactor auxiliary contacts are interlock
contacts preventing simultaneous pulling in both the hoist and lower
contactors and the normally closed auxiliary contacts extend control
power to the speed control circuits |
the normally
closed and normally open hoist and lower contactor auxiliary contacts
extend control power to the speed control circuits |
|
D |
The
progressive operation of the contactors marked "1A" through "4A"
provide the winch hoist controller shown in the illustration with what
functionality? Illustration EL-0102 |
accumulation |
regenerative
braking |
dynamic
braking |
acceleration |
|
B |
Which of the
listed conditions occur when '4th point lower' is selected on the
winch hoist controller shown in the illustration? Illustration EL-0102 |
Contactors
'H', '1A', '2A', and' 3A' drop out. |
Contactors
'L', '1A', '2A' and '3A' pull in. |
Master
switch contacts "3", "4", "5, "6", and "7" close. |
Master
switch contacts "3", "5", "6", "7", and "8" close. |
|
D |
For more
complete vessel protection when using an impressed current catholic
system, what other features are built into the system? |
the hull's
magnetic fields are aligned with a solid-state degaussing circuit
using SCR's |
all ship's
service alternators have additional temperature sensing devices and a
thermal recorder installed |
machinery on
deck and in the engine room is first coated with zinc chromate before
final painting |
straps
connect the rudder with the hull and the propeller shaft is grounded
through a slip ring/brush arrangement |
|
D |
What is the
function of the electric brake on a deck cargo winch? |
automatically govern the hoisting speed of the load |
automatically govern the lowering speed of the load |
automatically engage when the winch motor current is reaching full
load |
automatically hold the load if power to the winch motor is
disconnected |
|
D |
In the event
of a power failure during cargo loading operations, the movement of an
electric powered cargo winch will be stopped by what means? |
a hand
operated band brake |
a manual
override switch |
the weight
of the load on the boom |
a spring set
brake |
|
C |
When the
control handle is in the 'off' position, what is the status of the
solenoid actuated brake of an electric winch? |
energized
and the brake is released |
energized
and the brake is set by a spring |
de-energized
and the brake is set by a spring |
de-energized
and the brake is released |
|
C |
What does
the component labeled "B" shown in the illustration represent?
Illustration EL-0093 |
shielded
lamp |
bridge
rectifier |
hand-cranked
generator |
selsyn motor |
|
D |
As shown in
the illustration, which of the following statements is correct
concerning the circuits in a sound powered telephone system?
Illustration EL-0093 |
Both the
talking and ringing circuits are common circuits. |
The talking
circuit is a selective circuit and the ringing circuit is a common
circuit. |
Both the
talking and ringing circuits are selective circuits. |
The talking
circuit is a common circuit and the ringing circuit is a selective
circuit. . |
|
B |
Concerning
the illustrated fire detection and alarm system, what statement is
true concerning the wiring between zones? Illustration EL-0114 |
The zones
are all connected in series by means of the ground locating switches
only. |
The zones
are all connected in series by means of the fire locating switches and
the ground locating switches. |
The zones
are all connected in parallel by means of the fire locating switches
and the ground locating switches. |
The zones
are all connected in series by means of the fire locating switches
only. |
|
D |
The
pushbutton on the handset of a ship's sound-powered telephone must be
depressed in order to do what? |
talk then
released to listen |
ring the
station being called |
listen then
released to talk |
both talk
and listen |
|
A |
Where is the
power necessary to energize the howler "relay" coil at the engine room
station as shown in the illustration? Illustration EL-0093 |
comes from
each station's hand cranked generator |
is supplied
from a battery or ship's power |
comes from
pushing a button on the handset |
is conducted
through the relay's contacts |
|
C |
Impressed
current catholic hull protection systems are commonly used on modern
vessels. What are these systems designed to replace or reduce? |
electroplating of the hull |
vacuum tube
degaussing systems |
sacrificial
zinc anodes |
repeated
painting of the hull |
|
D |
As part of a
routine maintenance program for deck machinery motor controllers, what
should be done? |
remove
covers exposed to the weather and drain water each week |
remove motor
covers and ventilate as weather permits |
Check drum
switch contact pressure every three months |
inspect
electrical wiring for evidence of corrosion or discoloration at
connections |
|
C |
If deck
machinery is expected to be idle for an extended period of time, what
should be done? |
have
electrical safety gloves available in case of electrical shock before
running |
perform a
'high pot' test to determine the condition of the insulation |
energize
space heaters to prevent the condensation of moisture |
water wash
the motor and controller to remove any salt that may interfere with
smooth operation |
|
C |
As shown in
the illustrated wiring diagram for an engine order telegraph system,
what statement concerning the constant ringing and trouble alarm is
true? Illustration EL-0113 |
The constant
ringing and trouble alarm sounds when there is a power loss from the
115 VAC power supply to the system. |
The constant
ringing and trouble alarm sounds when the transmitter rotor and
corresponding indicator rotor are in correspondence. |
The constant
ringing and trouble alarm sounds when the acknowledge handle and
indicator arrow are not on the same order. |
The constant
ringing and trouble alarm sounds when there is a power loss from the
battery or emergency switchboard as appropriate. |
|
C |
Erratic
operation of the device represented in the diagram labeled "A" shown
in the illustration could be traced to what condition? Illustration
EL-0092 |
improper
contact at "S" slip rings or "R" connections |
a low
three-phase voltage supply |
improper
contact at "R" slip rings or "S" connections |
a high
three-phase voltage supply |
|
C |
If it is
required that the coils 'R1-R2-R3' in the indicator of figure "A",
turn opposite to those in the transmitter, as shown in the
illustration, what action should be taken? Illustration EL-0092 |
No action is
needed. |
Reverse the
60 Hz supply connections to 'S1' and 'S2'. |
Interchange
leads 'R1' and 'R3'. |
Interchange
leads 'R2' and 'R3'. |
|
C |
As shown in
figure "1" of the illustration, a correctly connected synchronous
transmission causes the receiver to be in correspondence with the
transmitter. If the receiver is out of correspondence, 180 degrees out
of zero, but the torque direction is correct as shown in figure "2",
what figure shows the incorrect connections responsible for this
condition? Illustration EL-0150 |
A |
C |
B |
D |
|
C |
Which of the
following conditions will occur if the brake solenoid coil burns out
on a cargo winch with an electrical brake? |
Nothing will
happen; the winch will continue to operate as usual. |
The motor
will over speed and burn up. |
The brake
will be set by spring force. |
The load
suspended from the cargo boom will fall. |
|
B |
The winch
shown in the illustration will operate normally in all speeds in both
directions, with the exception that it will not accelerate into 'fifth
point' hoist or 'fifth point' lower. What would be a possible cause?
Illustration EL-0102 |
master
switch contacts "MS 8' are welded closed |
time delay
relay '3T' coil is open-circuited |
master
switch contact 'MS 7" fails to close |
the
contactor '5A' coil is open-circuited |
|
D |
As shown in
the illustration, what is responsible for maintaining the "UV" relay
energized when the master switch handle is moved away from the "off"
position? Illustration EL-0102 |
MS 2'
contacts |
MS 1'
contacts |
normally
closed 'OL' contacts |
normally
open 'UV' contacts |
|
D |
In the
system shown in the illustration, the engine room station is unable to
signal any other station, nor is any other station able to signal the
engine room station. The engine room station can, however, ring itself
by proper positioning of its selector switch. What is the most
probable cause of this problem? Illustration EL-0093 |
The coil of
component "C" of the problem station is open circuited. |
The selector
switch is grounded at the problem station diverting current from the
other stations' ringing devices. |
The switch
at component "A" of the problem station is stuck open. |
There is an
open between terminal "C" of the problem station and the common wire
of the multi-conductor cable to the other stations. |
|
A |
In the
circuit 'B' of the illustration, what would be the result of the upper
heating element being burned out and open circuited? Illustration
EL-0041 |
low heat
(series) position would result in no heat at allmedium heat (single)
position would result in no heat at allhigh heat (parallel) position
would result in medium heat |
low heat
(series) position would result in low heatmedium heat (single)
position would result in medium heathigh heat (parallel) position
would result in medium heat |
low heat
(series) position would result in no heat at allmedium heat (single)
position would result in medium heathigh heat (parallel) position
would result in medium heat |
low heat
(series) position would result in low heatmedium heat (single)
position would result in medium heathigh heat (parallel) position
would result in medium heat |
|
B |
What
condition associated with a lead-acid battery cell can cause the
plates to partially short-out and cause the cell to fail to hold a
charge. |
dirty or
acid-wet tops and sides of batteries |
accumulation
of sediment within the cells due to excessive overcharging and
discharging |
sulfation of
the plates due to consistent undercharging or leaving the battery in a
discharged state |
lime
accumulation on both the positive and negative terminal posts |
|
A |
When
troubleshooting a lead-acid storage battery, what is the best method
for detecting a weak or dead cell? |
comparing
the specific gravity of the electrolyte in each cell |
taking an
open circuit voltage test of individual cells |
taking each
cell's temperature with a calibrated mercury thermometer |
visually
inspecting the electrolyte levels of each cell |
|
D |
As the
electrolyte level in the cells of a lead-acid battery evaporates over
time, what will tend to happen to the specific gravity of the
electrolyte in the cells as the level drops due to evaporation? |
Although the
specific gravity will change due to evaporation, there is no
predictable tendency either way. |
The specific
gravity of the electrolyte will decrease as only the sulfuric acid
will evaporate from the electrolyte solution. |
The specific
gravity of the electrolyte will remain unchanged as both the water and
sulfuric acid will evaporate from the electrolyte solution. |
The specific
gravity of the electrolyte will increase as only the water will
evaporate from the electrolyte solution. |
|
C |
What could
prevent a lead-acid battery from accepting a full charge? |
Attempting
to force charging current into the battery in the opposite direction
to that which occurs during discharge. |
Topping off
low electrolyte levels (due to evaporation) with distilled water. |
Leaving the
battery in a discharged condition for a great length of time. |
Coating
terminal posts with an anti-oxidant grease approved for battery use. |
|
C |
To determine
the state of charge of a nickel-cadmium wet-cell storage battery
during charging and discharging, what is the most reliable method? |
Checking the
electrolyte level in the cells. |
Measuring
the voltage across the cells. |
Checking the
electrolyte specific gravity in the cells. |
Measuring
the battery current. |
|
D |
A
split-phase induction squirrel-cage motor will not start and come up
to speed, even though the rated voltage, rated frequency, and rated
load are applied. Which of the following troubles would be suspected? |
a shorted
rotor bar |
a shorted
centrifugal switch |
a shorted
thermal protector |
an open run
or start winding |
|
D |
A lightly
loaded three-phase squirrel-cage induction motor, while running,
begins to vibrate excessively but continues to run. After shutting
down the motor, the motor will not restart, but makes growling noises,
overheats, and smokes. What caused this? |
The motor
tripped-out on under load. |
The branch
circuit breaker tripped open. |
The source
voltage or frequency was too low. |
One of the
lines feeding the motor has an open phase, resulting in
single-phasing. |
|
D |
The leads
from a ohmmeter are attached to the leads of the opposite ends of an
AC motor stator field coil. If a reading of infinity is obtained, what
does this indicate? |
grounded
field coil |
shunted
field coil |
shorted
field coil |
open field
coil |
|
D |
As shown in
the illustrated diagnostic setup for locating a shorted field coil of
a ten-pole synchronous motor, if 240 VAC 60-Hz is applied across the
brushes, what would be the individual voltage drops measured across
each field coil assuming that none of the field coils are shorted?
Illustration EL-0202 |
6 VAC |
48 VAC |
12 VAC |
24 VAC |
|
A |
Grounds
occurring in electrical machinery as a result of insulation failure
may result from deterioration over time and excessive heat. What could
be another contributing cause? |
extended
periods of vibration |
extended
operation at normal loads |
extended
periods of operation at low ambient temperature |
extended
periods of operation at low load |
|
A |
How may
temporary repairs to an open DC propulsion armature coil be made,
allowing continued operation until permanent repairs can be made? |
disconnecting coil ends, insulating each, and short circuiting the two
commutator bars |
connecting
the coil ends directly to a pair of negative brushes |
grounding
the coil ends and short circuiting the commutator bar |
removing the
sparking brushes |
|
C |
What would
excessive sparking at the brushes of a running DC motor be an
indication of? |
water vapor
absorption |
normal
operation |
a dirty
commutator |
increased
brush capacity |
|
A |
What is the
most effective method of locating a loose commutator bar in a D.C.
motor? |
sounding
each bar with a light weight hammer |
visual
inspection |
checking
with a calibrated torque wrench |
jiggling
each by hand |
|
C |
If a D.C.
motor hums, but does not run when energized, which of the listed
conditions could exist? |
No load on
the motor |
Blown fuse
or tripped circuit breaker |
Tight
bearings/frozen shaft |
Tripped
overload |
|
C |
Besides
checking for grounds, for what other purpose can a megohmmeter be used
on a DC motor? |
checking for
undercut mica |
checking for
a shorted field pole |
checking for
an open field coil |
checking for
reversed interpole polarity |
|
D |
When using a
megohmmeter to determine which shunt field coil is grounded in a DC
machine, what must you do? |
use a motor
driven high capacity megohmmeter |
insulate the
field frame from the ship's hull |
remove all
main line lead connections before testing |
disconnect
each shunt field coil before testing |
|
B |
If the motor
shown in the illustration will not start when the "off-run" switch is
placed in the run position, which of the listed components should be
checked FIRST? Illustration EL-0017 |
check the
main contactor coil for continuity, replace as necessary |
check the
overload relay for tripped condition, reset as necessary |
check the
overload relay (OL) heaters for continuity, replace as necessary |
check the
disconnect switch open, open as necessary |
|
D |
What can be
the cause of excessive heat or burning contacts in an operating motor
controller? |
low motor
starting torque |
burned out
operating coil |
high ambient
temperature |
loose
connections or low contact pressure |
|
A |
The motor
fails to start on an attempted startup. With the start button
depressed, a voltmeter reading between 1 and 5, as in figure "A" shown
in the illustration, indicates line voltage available to the control
circuit, what should be your next step in the troubleshooting process?
Illustration EL-0007 |
attempt to
reset the overload relay and determine the cause of the overload if
applicable |
test the
stop button for continuity and replace if necessary |
insure that
the disconnect switch (DS) is closed |
test the
contactor coil "M" for continuity and replace if necessary |
|
B |
As shown in
figure "B" of the typical ground fault relay shown in the
illustration, what statement concerning the leakage current setting
adjustment is true? Illustration EL-0223 |
Setting the
leakage current for too high a value may increase the likelihood of
nuisance trips and setting the leakage current for too low a value may
result in incidental damage due to a ground fault. |
Setting the
leakage current for too low a value may increase the likelihood of
nuisance trips and setting the leakage current for too high a value
may result in incidental damage due to a ground fault. |
Setting the
leakage current for too high or too low a value may increase the
likelihood of nuisance trips. |
Setting the
leakage current for too high or too low a value may result in
incidental damage due to a ground fault. |
|
B |
In order to
properly set up programmable motor protection, it is necessary to know
the locked rotor current of a motor. Given the chart of code letters
for locked-rotor kVA/HP and the necessary instructions shown in the
illustration, calculate the estimated locked rotor current for the
motor represented by the illustrated motor nameplate using a mid-range
value for the code letter, assuming the motor is to run at 440 VAC
__________. Illustration EL-0175 |
34.7 amps |
43.7 amps |
60 amps |
75.6 amps |
|
B |
If the
cooling water system is isolated for repairs, but it is still
desirable to run the alternator pictured in figure "A" of the
illustration, what must be done? Illustration EL-0037 |
The
emergency air inlet panel and air outlet doors must remain closed,
which requires the alternator to be run only at reduced loads. |
The
emergency air inlet panel and air outlet doors must be opened and only
then can the alternator be run, but at reduced load. |
The
alternator may not be run without cooling water under any
circumstances. |
The
emergency air inlet panel and air outlet doors must be opened, but in
doing so allows the alternator to be run at rated load. |
|
C |
If a
shipboard AC generator experiences a failure to produce a voltage,
what may be the cause? |
excessive
locked-rotor current |
a rotating
slip ring |
an open in
the rotor field circuit |
the brushes
shifting out of the neutral plane |
|
C |
How can the
loss of residual magnetism in an alternator or generator be corrected? |
allowing the
generator to run at 10% of normal speed for 5 minutes |
running the
rotor in the opposite direction for 5 minutes |
using a
storage battery or battery charger to 'flash' the field |
running the
generator at normal speed with the field rheostat fully
counterclockwise |
|
A |
#1 SSDG was
operating in parallel with #2 SSDG in supplying the 480 VAC main bus
while sharing the electrical load evenly. As a result of a problem, if
#1 SSDG begins to motorize, but the generator has not yet tripped out
by the action of the reverse power relay, what would be the indication
of this? |
The kilowatt
meter of #1 SSDG would indicate a negative wattage (a reversed
reading). |
The ammeter
of #1 SSDG would indicate a higher amperage than when the load was
equally shared with #2 SSDG. |
The power
factor meter of #1 SSDG would indicate unity (1.0). |
The kilowatt
meter of #1 SSDG would indicate a higher wattage than when the load
was equally shared. |
|
A |
On a
steamship, if #1 SSTG fails to produce a voltage while in the
automatic voltage control mode, but successfully produces a voltage
while in the manual control mode, what statement is true? |
The voltage
failure would most likely be the result of a failed voltage regulator. |
The voltage
failure would most likely be the result of an open field winding. |
The voltage
failure would most likely be the result of a failed exciter generator. |
The voltage
failure would most likely be the result of an open manual rheostat. |
|
D |
What may
cause brush sparking in a DC generator during commutation? |
eddy
currents in the armature core |
hysteresis
in the armature core |
excessive
brush pressure |
misalignment
of the brush rigging |
|
A |
Hysteresis
is one cause of electrical power loss associated with electricity
generation equipment. What phenomenon results in hysteresis? |
heat
generated by magnetic polarity reversals |
excessive
field current |
pulsating
terminal current |
arcing at
the brushes |
|
D |
What can
cause uneven wear of the commutator surface on a direct current
generator? |
rapid change
in load |
excessive
operation at light load |
unequal pole
spacing |
incorrect
brush staggering |
|
B |
If a
self-excited DC generator running at rated speed fails to deliver an
output voltage, which of the following conditions may be a cause of
this difficulty? |
Excessive
residual magnetism. |
An open
shunt-field circuit. |
Excessive
brush pressure. |
A shorted
shunt-field circuit. |
|
B |
In an
ungrounded distribution system, as compared to a normal indication,
what is the indication on a switchboard of a current carrying
conductor making an accidental electrical contact with a wiring metal
conduit? |
lower
switchboard wattmeter reading than normal |
totally
darkened switchboard ground-detecting light |
higher
switchboard voltmeter reading than normal |
reading of
1.0 on the power factor meter |
|
B |
From the
information given in the illustration, what would be the ampere
capacity at full load of each of the main ship service diesel
generators if operating at the rated power factor of 0.8? Illustration
EL-0106 |
2500 amps |
3011 amps |
5208 amps |
3125 amps |
|
C |
As shown in
figure "A" of the illustration, what type of ground fault detection
system is illustrated? Illustration EL-0132 |
a neutral to
ground current transformer system |
a
core-balance current transformer system |
a direct
current injection system |
a set of
ground detection lamps system |
|
C |
In order to
definitively determine whether or not fuse "1", shown in the
illustration is blown using an on-line testing technique, across what
points would you connect the voltmeter leads? Illustration EL-0062 |
the top of
fuse "1" and the bottom of either fuse "2 or 3" |
the bottom
of fuse "1" and the bottom of either fuse "2 or 3" |
the bottom
of fuse "1" and the top of either fuse "2 or 3" |
the top of
fuse "1" and the top of either fuse "2 or 3" |
|
B |
Assuming
that 450 VAC is the source voltage at the circuit breaker, if 450
volts AC were measured across the load as shown in the illustration as
shown in figure "B" of the illustration, what would this indicate?
Illustration EL-0083 |
a properly
operating circuit |
an open
winding between the reference point "X" and the 25% tap connection |
an open
winding between reference point "Y" and the 75% tap connection |
a ground on
one side of the supply voltage to the autotransformer |
|
A |
As shown in
the illustration of a vessels navigational lighting circuit, if port
running light "1" burns out, the trouble buzzer will sound and the
port running light trouble lamp will illuminate. Switching to port
running light "2" clears the alarm. If port running light "1" is
replaced with a light of a smaller wattage and the circuit is switched
back to port running light "1", which of the following is true?
Illustration EL-0058 |
There may be
insufficient current to energize the trouble relay coil and to open
the contacts to silence the alarm. |
The new
lower wattage light at port running light "1" will immediately burn
out. |
The trouble
buzzer may not have sufficient voltage to provide sound. |
The trouble
relay coil will overheat. |
|
A |
The ground
indicating light on the main electrical switchboard is indicating a
ground. What is the best procedure for locating the grounded circuit? |
open the
circuit breakers on the distribution panel, one at a time, until the
lights no longer indicate a ground |
trace the
circuit paths while looking for burned spots |
check
circuit resistances with a megohmmeter connected between the grounded
line and the distribution panel framework |
check all
circuits for continuity |
|
A |
As shown in
figure "A" of the ungrounded distribution system with possible ground
faults shown in the illustration, under what conditions would an
outage likely occur due to a ground fault causing a circuit breaker to
trip? Illustration EL-0129 |
two ground
faults associated with different phases |
a single
ground fault associated with any phase |
ground
faults do not result in outages regardless of the number and location
of faults |
two ground
faults associated with the same phase |
|
B |
During the
start-up of the circuit shown in figure "B" of the illustration, it is
noted that the ends of component "4" remain lighted but the tube does
not illuminate. What is likely the cause of this problem? Illustration
EL-0081 |
component
"2" is closed |
component
"5" contacts are stuck closed |
component
"3" is open |
component
"4" is the wrong wattage |
|
C |
What effect
will increasing the power source frequency have in a capacitive
circuit? |
it will not
have any effect on the average current value |
it will
decrease the average current in the circuit |
it will
increase the average current in the circuit |
it will not
have any effect on the capacitive reactance |
|
C |
Using the
trouble analysis chart and faults table provided in the illustration,
if the gyrocompass was malfunctioning, but no fault codes are present
on the display unit, what is most likely the problem if the DC/DC
converter LED status indicator is functioning properly, but the CPU
LED status indicator is not blinking? Illustration EL-0195 |
The AC/DC
power supply is malfunctioning. |
Ship's power
is not available. |
The CPU
assembly is malfunctioning. |
The DC/DC
converter is malfunctioning. |
|
D |
Which of the
procedures or conditions listed could result in damaging a transistor
beyond repair? |
Installing a
transistor whose current rating exceeds the design circuit current. |
Applying
silicone grease between the heat sink and the transistor mounting. |
Providing
insufficient voltage to the input circuit. |
Providing
incorrect polarity to the collector circuit. |
|
B |
If a digital
multimeter is set up as shown in figures "A" and "B" of the
illustration, what is the status of the silicon diode if the display
reads 4.7 ohms when configured as in figure "A" and reads 490 ohms
when configured as in figure "B"? Illustration EL-0211 |
the diode is
open |
the diode is
functioning properly |
the diode is
shorted |
the diode is
intermittently open |
|
A |
When
troubleshooting most electronic circuits, what voltmeter
characteristic can minimize the 'loading effect'? |
input
impedance much greater than the impedance across which the voltage is
being measured |
sensitivity
of more than 1000 volts/ohm |
input
impedance much less than the impedance across which the voltage is
being measured |
sensitivity
of less than 1000 ohms/volt |
|
A |
When
troubleshooting an electronic circuit, an unreliable high resistance
"cold" solder joint can be located with the aid of an ohmmeter. Once
the problem has been located, what should be done? |
reheat
connection with a soldering tool and recheck with an ohmmeter |
do nothing
as this is the normal condition |
reheat the
circuit in an oven to an even temperature and recheck with an ohmmeter |
reheat the
connection with a match and recheck with an ohmmeter |
|
A |
A full-wave
rectifier has one diode burned out in an open condition, what will be
the output characteristic of the device? |
Half-wave
rectified |
Zero |
Equal to the
AC input |
Full-wave
rectified |
|
B |
Normally,
what is the FIRST step in troubleshooting a transistor mounted on a
circuit card? |
carefully
remove the transistors from the card |
visually
inspect the card |
give the
circuit an initial test with a signal generator |
test for
continuity with a low voltage DC supply |
|
B |
If both the
'high level' and 'low level' alarms come on for the same address of a
centralized control console, what is the most likely failure? |
low level |
sensor
failure |
failed alarm |
extremely
high level |
|
D |
In addition
to improper brush pressure or seating, what can result in excessive
sparking at the brushes of a DC propulsion motor? |
operating at
continuously varying loads such as during maneuvering |
reversed
armature polarity with respect to the field |
reversed
main field polarity with respect to the armature |
improper
positioning of brush rigging outside the neutral plane |
|
A |
While
standing an "at sea watch" onboard a modern rectified DC
diesel-electric drive ship you notice the transformer core temperature
slowly rising. What should be your FIRST action? |
check the
transformer ventilation fans for proper operation |
reduce load
by tripping lighting circuits |
send the
oiler to look for fires in the transformer |
notify the
bridge that you need to slow down |
|
A |
Refer to the
diagram of the AC turboelectric drive system as shown in the
illustration. The propulsion motor operates from maneuvering speed to
full ahead speed in the ahead direction. The propulsion motor will not
operate at any speed in the astern direction. What is most likely the
problem? Illustration EL-0142 |
The
reversing contactor (R) fails to pull in. |
The AC
propulsion motor field winding fails to reverse in polarity. |
The AC
propulsion motor has an open astern winding. |
The turbine
of the turbo-alternator fails to rotate in the astern direction. |
|
D |
Refer to the
simplified diagram of the AC synchronous electric motor drive system
as shown in the illustration. The propulsion motor operates from
maneuvering speed to full ahead speed in the ahead direction. The
propulsion motor will not operate at any speed in the astern
direction. What is most likely the problem? Illustration EL-0155 |
The AC
propulsion motor field winding fails to reverse in polarity. |
The power
supply to the controlled rectifier fails to achieve a phase sequence
reversal. |
The AC
propulsion motor has an open astern winding. |
The output
of the controlled inverter fails to achieve a reversal in phase
sequence. |
|
B |
On a vessel
with turbo-electric drive, which of the following conditions would
indicate that the propulsion motor had dropped out of synchronization
with the propulsion generator? |
Closed
contact in the field circuits |
Excessive
vibration of the vessel |
Overheated
crosstie busses |
Tripped main
motor interlocks |
|
C |
A digital
multimeter is set up as shown in the illustration to test an
individual element of a three-phase immersion heater. The elements are
connected across terminals 1 and 4, 2 and 5, and 3 and 6 as shown. The
reading across terminals 1 and 4 is 32 ohms. The reading across
terminals 2 and 5 is 32 ohms. The reading across terminals 3 and 6 as
shown is "OL" ohms. What is condition is indicated? Illustration
EL-0216 |
The element
across terminals 3 and 6 is short-circuited. The other two elements
are functioning properly. |
The element
across terminals 3 and 6 is functioning properly. The other two
elements are open-circuited. |
The element
across terminals 3 and 6 is open-circuited. The other two elements are
functioning properly. |
The element
across terminals 3 and 6 is functioning properly. The other two
elements are short-circuited. |
|
A |
Refer to
figure "A" representing an electric oven as shown in the illustration.
With the oven turned on, the power available indicator light is off,
the oven on indicator light is off, and only elements "6" and "7"
appear to be producing heat. Which fuse is blown? Illustration EL-0041 |
L1 10A line
fuse is blown |
L2 10A line
fuse is blown |
L3 10A line
fuse is blown |
L1 1A
control fuse is blown |
|
A |
Refer to
figures "1" and "2" of the basic synchronous transmission system shown
in the illustration. Figure "1" shows a properly connected system
where the receiver TR remains in correspondence with the transmitter
TX. In figure "2", although properly zeroed, the receiver goes out of
correspondence with the transmitter due to improper connections
resulting in reverse torque direction. Which connection error results
in this behavior? Illustration EL-0149 |
A |
B |
C |
D |
|
C |
Which of the
following conditions will occur if the brake solenoid coil burns out
on a cargo winch with an electrical brake? |
The load
suspended from the cargo boom will fall. |
Nothing will
happen; the winch will continue to operate as usual. |
The brake
will be set by spring force. |
The motor
will over speed and burn up. |
|
C |
The winch
shown in the illustration operates in any of the positions with the
master switch in the 'lower' direction, but will not 'hoist' in any of
the master switch hoist speed positions. Which of the listed faults
could be the cause? Illustration EL-0102 |
Master
switch contact 'MS 3' may have defective springs. |
Master
switch contact 'MS 5' may have defective springs. |
Master
switch contact 'MS 4' may have defective springs. |
Master
switch contact 'MS 2' may have defective springs. |
|
D |
An open
primary coil in a simple potential transformer will be indicated by
which of the listed conditions? |
An infinite
resistance value on the secondary coil. |
Overloaded
secondary coil. |
Low
resistance value on the primary coil. |
No voltage
on the output of the secondary coil. |
|
A |
A 480/120
VAC step down control transformer as configured in figure "E" of the
illustration produces 89 VAC across its secondary winding (across X1
and X2) with 480 VAC applied to the primary winding (across H1 and
H2). What condition is indicated? Illustration El-0123 |
A few
shorted turns in the secondary winding |
An open
primary winding (across H1 and H2) |
An open
secondary winding (across X1 and X2) |
A few
shorted turns in the primary winding |
