Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Marine Electrical Systems (Set 32)
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Question 1 of 30
As shown in figure "A" of the illustration, the load-commutated inverter drive illustrated has how many pulses? EL-0159
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30 MCQs #1 As shown in figure "A" of the illustration, the load-commutated inverter drive illustrated has how many pulses? EL-0159 #2 The propulsion motor most often utilized in an ac drive system operating in the moderate to high power range is of what type? #3 As shown in figure "B" of the illustration, what statement is true concerning "regenerating" operation? EL-0162 #4 How is the main shaft rotation on an AC diesel-electric propulsion vessel normally reversed? #5 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? EL-0164 #6 A shown in figure "A" of the illustrated propulsion motor variable speed drive, what statement is true? EL-0140 #7 By what common means is the speed of the AC propulsion motor on a diesel-electric propulsion ship controlled? #8 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? #9 What type of motor is generally used in DC propulsion drive systems? #10 How is the main propeller shaft rotation of a rectified DC diesel-electric drive normally reversed? #11 In a diesel electric plant, raising the generator's field excitation current will have what effect on the DC propulsion motor speed? #12 What equipment for modern SCR rectified DC propulsion drive systems is usually included in the package? #13 What statement is TRUE concerning the Azipod propulsion system? #14 Which of the following statement is TRUE concerning Azipod propulsion systems? #15 In an azipod propulsion system, how is three phase, frequency and voltage controlled power delivered to the synchronous propulsion motor stator windings? #16 In an azipod propulsion system, how is direct current delivered to the synchronous propulsion motor rotor for synchronous operation? #17 In an azipod propulsion system, how is the azipod unit itself rotated for the purposes of directing the thrust in accordance with steering commands from the bridge? #18 For the purposes of high voltage marine practice, what is the threshold voltage where all voltages below this value are considered low voltage? #19 What is a disadvantage to the use of high voltage systems onboard ship? #20 What is the most common and reliable type of circuit breaker used for high voltage practice aboard ship? #21 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? #22 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? #23 Before work may safely commence on a high voltage system, what must first be done after disconnection and isolation? #24 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? #25 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? #26 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? #27 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)? #28 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? #29 Which station's emergency loudspeaker must allow for two-way communication? #30 Assuming the vessel has an engine control room, where is an engineers' assistance- needed alarm required to produce an audible signal?
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