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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.
C Using the catalog selection chart shown in Illustration EL-0180, determine the correct catalog number for a motor starter that meets the following criteria:
{{{
NEMA                      Open enclosure
3-pole                    Rated at 45 continuous amperes
Vertically mounted        Electronic overload relay-Ground fault feature set
Reversing starter         Operating coil rated at 24 VAC/60 Hz}}}
AE19GNVB5G045 AN19AN0A5E005 AN59GNVT5G045 CN16GNVT5G045
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.
C Using the catalog selection chart shown in Illustration EL-0180, determine the correct catalog number for a motor starter that meets the following criteria:
{{{
NEMA                      Open enclosure
3-pole                    Rated at 45 continuous amperes
Vertically mounted        Electronic overload relay-Ground fault feature set
Reversing starter         Operating coil rated at 24 VAC/60 Hz}}}
AE19GNVB5G045 AN19AN0A5E005 AN59GNVT5G045 CN16GNVT5G045
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? 212F 110F 145F 165F
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 10F the battery temperature is above 80F subtract 4 correction points for each 10F the battery temperature is above 80F subtract 10 correction points for each 4F the battery temperature is above 80F add 10 correction points for each 4F the battery temperature is above 80F
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 90F 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 10C 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 90F.
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 0Â position. What does this indicate? the alternator voltages are 180Â 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 350C 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 40C 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