Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Marine Electrical Systems (Set 36)
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Incorrect brush pressure can result in accelerated brush wear on a DC generator. What statement concerning brush pressure is true?
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30 MCQs #1 Incorrect brush pressure can result in accelerated brush wear on a DC generator. What statement concerning brush pressure is true? #2 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? #3 Why are electric strip heaters used in motor controllers? #4 Before working on an electric cargo winch master switch or controller, what should be done? #5 Which of the following methods should be used to dress the face of silver-plated contacts? #6 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? #7 High pressure compressed air should not be used to clean electric motors or controller equipment. Why not? #8 What device can be used to check the calibration of a circuit breaker? #9 Which of the listed pairs of materials make the best insulators? #10 As shown in figure "A" of the illustration, what phenomenon is illustrated with respect to electrical cables and ground? EL-0126 #11 When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking? #12 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? #13 As part of a routine maintenance program for deck machinery motor controllers, what should be done? #14 If deck machinery is expected to be idle for an extended period of time, what should be done? #15 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? #16 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? EL-0102 #17 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? EL-0102 #18 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? #19 Upon loss of field excitation of a generator operating in parallel with others, what must be done? #20 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? #21 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? #22 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? EL-0014 #23 As shown in the illustrated one-line diagram of a two-tiered emergency power system for a passenger ship, what statement is true? EL-0166 #24 You are in the planning stages of replacing a battery charger, where an exact duplicate of the charger to be replaced is not available. Obviously the charger must be suitable for the battery to be charged. According to 46 CFR, Subchapter J (Electrical Engineering), which of the following is a true statement concerning battery chargers? #25 According to 46 CFR, Subchapter J (Electrical Engineering), which of the following statements concerning battery installations is correct? #26 Suppose a cargo vessel of 1600 gross tons or more is fitted with emergency storage batteries for the purpose of supplying emergency lighting and power. According to 46 CFR, Subchapter J (Electrical Engineering), the capacity of the storage batteries is such that they should be able to successfully power the emergency loads for a period of 18 hours. Beginning with fully charged batteries, what is the minimum allowable voltage of the batteries after the 18 hour discharge period assuming a nominal voltage rating of 24 VDC and operating at rated capacity. #27 Suppose a cargo vessel of 1600 gross tons or more is fitted with emergency storage batteries for the purpose of supplying emergency lighting and power. According to 46 CFR, Subchapter J (Electrical Engineering), the capacity of the storage batteries is such that they should be able to successfully power the emergency loads for a period of 18 hours. Beginning with fully charged batteries, what is the minimum allowable percentage of the voltage rating of the batteries after the 18 hour discharge period assuming a nominal voltage rating of 24 VDC and operating at rated capacity. #28 In accordance with 46 CFR Part 112, a storage battery for an emergency lighting and power system must have the capacity to accomplish which of the following? #29 In accordance with 46 CFR, Subchapter J (Electrical Engineering), each diesel engine driven generator prime mover must have an over speed device, independent of the normal operating governor. If in testing the over speed device, what should be the trip point setting in terms of rated speed? #30 You are in the planning stages of setting the instantaneous trip of a ship's service generator circuit breaker. According to 46 CFR, Subchapter J (Electrical Engineering), what statement is true regarding the criteria for the instantaneous trip set point, assuming the generator is capable of being paralleled?
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