United States Coast Guard Marine Engineer Exam Questions Electrical Question Choice A Choice B Choice C Choice D Illustration BOOK Answer Number Question 12 1 C As shown in the illustration, which of the listed types of motor Across-the-line Capacitor Autotransformer Part-winding See illustration controllers and starters is indicated? number(s): EL-0012 12 2 B The full torque electric brake on an electric cargo winch functions act as a backup brake in automatically hold the automatically govern the automatically govern the to _____________. the event the mechanical load as soon as current lowering speed of the hoisting speed of the brake should fail to the machine is shut load load off 12 3 D You are performing an out-of-circuit test on the semi- conductor A low reading with red A low reading with red A low reading with black A low reading with black See illustration shown in the illustration. Using an ohmmeter on 'low power' lead on "A" and black lead on "A" and black lead on"A" and red lead lead on "A" and red lead number(s): EL-0068 setting and with leads properly inserted, which of the listed results lead on "C"; and a high lead on "B"; and a high on "B"; and a high on "C"; and a high would indicate a good Emitter-Base junction? reading with the leads reading with the leads reading with the leads reading with the leads reversed. reversed. reversed. reversed. 12 4 A When troubleshooting most electronic circuits, "loading effect" input impedance much input impedance much sensitivity of less than sensitivity of more than can be minimized by using a voltmeter with a/an greater than the less than the impedance 1000 ohms/volt 1000 volts/ohm ___________________. impedance across which across which the the voltage is being voltage is being measured measured 12 5 A On a vessel with turbo-electric drive, which of the following Excessive vibration of Tripped main motor Overheated crosstie Closed contact in the conditions would indicate that the propulsion motor had dropped the vessel interlocks busses field circuits out of synchronization with the propulsion generator? 12 6 B On some diesel-electric ships, the DC propulsion motor will only rotating brush alignment raising the generator lowering the generator decreasing excitation attain half speed when the generator fields are fully excited. engine speed engine speed Speeds above this are obtained by _____________. 12 7 A In a diesel electric plant, raising the generator's field excitation will increase in speed decrease in speed affect generator speed affect main motor speed cause the DC propulsion motor to ________. only if done in conjunction with higher generator engine speeds 12 8 C Electric propulsion coupling excitation is reduced at slow speeds increase speed control increase shaft torque prevent coupling prevent coupling to ___________. overheating slippage 12 9 A An electric tachometer receives the engine speed signal from a small generator mounted bimetallic sensing device stroboscopic sensing vibrating reed meter _______________. on the engine device generating a voltage proportionate to engine speed 12 10 B A three-phase alternator is operating at 450 volts with the 17.8 KW 23.2 KW 30.6 KW 37.8 KW switchboard ammeter indicating 300 amps. The kw meter currently indicates 163.6 KW, with a power factor of 0.7. If the power factor increases to 0.8, the KW meter reading would increase by ____________. 12 11 B A semiconductor that decreases in resistance with an increase in resistor thermistor diode thermopile temperature is known as a _____________. 12 12 A The shunt used in an ammeter should be connected in series with the load and parallel with the load and parallel with the load and series with the load and ____________. in parallel with the meter in series with the meter in parallel with the meter in series with the meter movement movement movement movement 12 13 D Brushless generators are designed to operate without the use of brushes slip rings commutators all of the above ___________. 12 14 C An operating characteristic appearing on the name plates of the type of winding input kilowatts temperature rise locked rotor torque shipboard AC motors is _____________. This document and more, available on Martin's Marine Engineering Page - www.dieselduck.net United States Coast Guard Marine Engineer Exam Questions Electrical 12 15 C Low horsepower, polyphase, induction motors can be started with compensator starters autotransformer starters across-the-line starters primary-resistor starters full voltage by means of _____________. 12 16 D Which of the listed devices may be installed on a large turbo- Temperature detector A CO2 fire extinguishing Electric space heaters to All of the above. electric alternating current propulsion generator? coils inserted in the system. prevent condensation of stator slots for measuring moisture. stator temperature. 12 17 D Moisture damage, as a result of condensation occurring inside of installing a light bulb in coating the switch box venting the switch box using strip heaters inside the cargo winch master switches, can be reduced by the pedestal stand internals with epoxy regularly the switch box __________________. sealer 12 18 A Which of the following conditions will occur if the solenoid coil The brake will be set by The motor will overspeed The load suspended Nothing will happen; the burns out on a cargo winch with an electrical brake? spring force. and burn up. from the cargo boom will winch will continue to fall. operate as usual. 12 19 C Which of the listed battery charging circuits is used to maintain a Normal charging circuit Quick charging circuit Trickle charging circuit High ampere charging wet-cell, lead-acid, storage battery in a fully charged state during circuit long periods of disuse? 12 21 C A ground can be defined as an electrical connection between the shunt field circuit breaker metal framework interpole wiring of a motor and its ____________. 12 22 C External shunts are sometimes used with ammeters to _______. increase meter sensitivity permit shunts with larger prevent damage to the enable the construction resistances to be utilized meter movement from of a compact meter with heat generated by the a virtually unlimited shunt range 12 23 B The output voltage of a 440 volt, 60 hertz, AC generator is prime mover speed exciter output voltage load on the alternator number of poles controlled by the _____________. 12 24 C Any electric motor can be constructed to be _____________. short proof ground proof explosion proof overload proof 12 25 C Which of the following statements represents the main difference Contactors control A relay is series Contactors can handle Contactors are made between a relay and a contactor? current and relays connected and a heavier loads than from silver and relays are control voltage. contactor is parallel relays. made from copper. connected. 12 26 A Which of the following statements is true concerning a The motor is started as Resistance is gradually The starting current is The field winding is polyphase synchronous propulsion motor? an induction motor. added to the rotor circuit. held below the rated energized for starting current. purposes only. 12 27 C Where a thermal-acting breaker is required to be used in an area cylindrical spring on the conical spring on the second bimetal element second electromagnet of unusually high, low, or constantly fluctuating temperatures, an contact arm contact arm ambient compensating element must be used. This element consists of a ______________. 12 28 A Which of the following statements represents an application of a To provide DC power for For use as a voltage For sensing flame in an To eliminate power silicon controlled rectifier? a main propulsion motor. reference diode. automated burner. supply hum. 12 29 B The electrolyte used in a nickel-cadmium battery is distilled diluted sulfuric acid potassium hydroxide lead sulfate zinc oxide water and ______________. 12 30 D Which of the damages listed can occur to the components of a Overheating of the winch Contamination of lube Sparking at the winch Rapid corrosion of switch winch master control switch, if the cover gasket becomes motor. oil. motor brushes. components. deteriorated? 12 31 B An accidental path of low resistance, allowing passage of open circuit short circuit polarized ground ground reference point abnormal amount of current is known as a/an ____________. 12 32 C A resistance in a circuit of unknown value is to be tested using both meters in series both meters in parallel the ammeter in series the ammeter in parallel the voltmeter/ammeter method. Therefore, the meters should be with the resistance with the resistance and the voltmeter in and the voltmeter in connected with _____________. parallel with the series with the resistance resistance This document and more, available on Martin's Marine Engineering Page - www.dieselduck.net United States Coast Guard Marine Engineer Exam Questions Electrical 12 34 C In general, polyphase induction motors can be started on full line compensator starters autotransformer starters across-the-line starters primary-resistor starters voltage by means of ______________. 12 35 B Which of the following statements concerning the maintenance of When necessary, they They should be filed with When black silver oxide If necessary, they should solid-silver contacts in relays and auxiliary control circuits is should always be a fine-cut file when is present, it should be held together with correct? dressed with a wire projections extend always be removed from moderate pressure while wheel. beyond the contact the contact surface with emery paper is drawn surface. coarse sandpaper. between the contacts. 12 36 A While starting a main propulsion synchronous motor, the motor has started field windings are slip rings are dirty power transmission ammeter pegs out at maximum and then returns to the proper properly grounded cables are grounded value after synchronization.