Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Marine Electrical Systems (Set 23)
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Question 1 of 30
On a steamship, if #1 SSTG fails to produce a voltage while in the automatic voltage control mode, but successfully produces a voltage while in the manual control mode, what statement is true?
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30 MCQs #1 On a steamship, if #1 SSTG fails to produce a voltage while in the automatic voltage control mode, but successfully produces a voltage while in the manual control mode, what statement is true? #2 What may cause brush sparking in a DC generator during commutation? #3 Hysteresis is one cause of electrical power loss associated with electricity generation equipment. What phenomenon results in hysteresis? #4 What can cause uneven wear of the commutator surface on a direct current generator? #5 If a self-excited DC generator running at rated speed fails to deliver an output voltage, which of the following conditions may be a cause of this difficulty? #6 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? EL-0062 #7 The ground indicating light on the main electrical switchboard is indicating a ground. What is the best procedure for locating the grounded circuit? #8 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? EL-0058 #9 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? #10 From the information given in the illustration, what would be the ampere capacity at full load of each of the main ship service diesel generators if operating at the rated power factor of 0.8? EL-0106 #11 Assuming that 450 VAC is the source voltage at the circuit breaker, if 450 volts AC were measured across the load as shown in the illustration as shown in figure "B" of the illustration, what would this indicate? EL-0083 #12 As shown in figure "A" of the ungrounded distribution system with possible ground faults shown in the illustration, under what conditions would an outage likely occur due to a ground fault causing a circuit breaker to trip? EL-0129 #13 During the start-up of the circuit shown in figure "B" of the illustration, it is noted that the ends of component "4" remain lighted but the tube does not illuminate. What is likely the cause of this problem? EL-0081 #14 As shown in figure "A" of the illustration, what type of ground fault detection system is illustrated? EL-0132 #15 What effect will increasing the power source frequency have in a capacitive circuit? #16 Which of the procedures or conditions listed could result in damaging a transistor beyond repair? #17 If a digital multimeter is set up as shown in figures "A" and "B" of the illustration, what is the status of the silicon diode if the display reads 4.7 ohms when configured as in figure "A" and reads 490 ohms when configured as in figure "B"? EL-0211 #18 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? EL-0195
Illustration EL-0195: the U.S. Coast Guard has not released this illustration. #19 When troubleshooting most electronic circuits, what voltmeter characteristic can minimize the 'loading effect'? #20 Normally, what is the FIRST step in troubleshooting a transistor mounted on a circuit card? #21 If both the 'high level' and 'low level' alarms come on for the same address of a centralized control console, what is the most likely failure? #22 A full-wave rectifier has one diode burned out in an open condition, what will be the output characteristic of the device? #23 When troubleshooting an electronic circuit, an unreliable high resistance "cold" solder joint can be located with the aid of an ohmmeter. Once the problem has been located, what should be done? #24 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? #25 In addition to improper brush pressure or seating, what can result in excessive sparking at the brushes of a DC propulsion motor? #26 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? #27 Refer to the diagram of the AC turboelectric drive system as shown in the illustration. The propulsion motor operates from maneuvering speed to full ahead speed in the ahead direction. The propulsion motor will not operate at any speed in the astern direction. What is most likely the problem? Illustration EL-0142 #28 Refer to the simplified diagram of the AC synchronous electric motor drive system as shown in the illustration. The propulsion motor operates from maneuvering speed to full ahead speed in the ahead direction. The propulsion motor will not operate at any speed in the astern direction. What is most likely the problem? Illustration EL-0155 #29 A digital multimeter is set up as shown in the illustration to test an individual element of a three-phase immersion heater. The elements are connected across terminals 1 and 4, 2 and 5, and 3 and 6 as shown. The reading across terminals 1 and 4 is 32 ohms. The reading across terminals 2 and 5 is 32 ohms. The reading across terminals 3 and 6 as shown is "OL" ohms. What is condition is indicated? EL-0216 #30 Which of the following conditions will occur if the brake solenoid coil burns out on a cargo winch with an electrical brake?
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