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Engine · 1,595 questions

Electricity - USCG Exam Questions

Marine electrical systems: motors and generators, switchboards and distribution, batteries, electronics, and control engineering.

Every question below is a real U.S. Coast Guard exam question with four choices. Answer one and the correct choice is revealed instantly, with the USCG reference and illustration where the question uses one.

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All Electricity questions

Questions 601–700 of 1,595 · page 7 of 16

  1. #602 Which of the following statements concerning figure "6" of the illustration is true? EL-0026 illustration
  2. #603 As shown in figure "6" of the illustration, what does the symbol represent as used in electrical drawings? EL-0026 illustration
  3. #604 Which electrical schematic symbol shown in the illustration represents a normally closed thermostat? EL-0059 illustration
  4. #605 Which of the electrical schematic symbols shown in the illustration represents a normally closed limit switch? EL-0059 illustration
  5. #606 What is the shape of the schematic symbol for an operational amplifier used in an analog circuit?
  6. #607 In figure "1" of the illustration, what type of circuit breaker trip element is featured? EL-0033 illustration
  7. #608 What statement is true concerning the electrical diagrams for the motor controller shown in the illustration? Illustration EL-0007 illustration
  8. #609 What type of electrical diagram for the autotransformer type motor controller is shown in the illustration? Illustration EL-0012 illustration
  9. #610 What type of electrical diagram for the electrical distribution system is shown in the illustration? Illustration EL-0014 illustration
  10. #611 What type of electrical diagram for the shunt wound DC motor is shown in the illustration? Illustration EL-0052 illustration
  11. #612 What type of electrical diagram for the steering control systems is shown in the illustration? Illustration EL-0192 illustration
  12. #613 What is the circuit shown in the illustration used to measure? EL-0024 illustration
  13. #614 What is the instrument called a galvanometer used to measure?
  14. #615 What is an ohmmeter used to measure?
  15. #616 What practice could potentially damage a multimeter?
  16. #617 In what situation would an electrical phase sequence indicator be useful?
  17. #618 An internal resistance is placed in series with the meter movement of which of the following instruments?
  18. #619 When a resistor is used as a shunt and is connected in parallel with a meter movement coil, what capability does this provide?
  19. #620 Periodic testing using a special camera may be performed to detect potentially dangerous loose or corroded bus bar and controller connections. What is...
  20. #621 What is an ammeter used to measure?
  21. #622 Why are external shunts sometimes used with ammeters?
  22. #623 How should the shunt used in an ammeter be connected?
  23. #624 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 o...
  24. #625 To properly use a clamp-on-type ammeter to check current flow, what must be done FIRST?
  25. #626 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... illustration
  26. #627 Which of the listed statements is correct when using an digital multimeter set up as an ohmmeter?
  27. #628 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? EL-02... illustration
  28. #629 When testing a capacitor with an digital multimeter set up as an ohmmeter, what would be the indication on the display when testing an initially disch...
  29. #630 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?
  30. #631 When compared to an electronic digital voltmeter, the main disadvantage of the Simpson 250 analog multimeter is which of the following?
  31. #632 In testing a hand cranked megger prior to use, what statement is true?
  32. #633 When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by a very specific me...
  33. #634 When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking?
  34. #635 In which of the situations listed will a megohmmeter give the most accurate readings?
  35. #636 What is the resistance reading at "1" on the megger scale illustrated in figure "A"? EL-0044 illustration
  36. #637 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.
  37. #638 When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?
  38. #639 As the electrolyte level in the cells of a lead-acid battery evaporates over time, what will tend to happen to the specific gravity of the electrolyte...
  39. #640 What could prevent a lead-acid battery from accepting a full charge?
  40. #641 To determine the state of charge of a nickel-cadmium wet-cell storage battery during charging and discharging, what is the most reliable method?
  41. #642 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...
  42. #643 A split-phase induction squirrel-cage motor will not start and come up to speed, even though the rated voltage, rated frequency, and rated load are ap...
  43. #644 As shown in the illustrated diagnostic setup for locating a shorted field coil of a ten- pole synchronous motor, if 240 VAC 60-Hz is applied across th... illustration
  44. #645 Grounds occurring in electrical machinery as a result of insulation failure may result from deterioration over time and excessive heat. What could be...
  45. #646 A lightly loaded three-phase squirrel-cage induction motor, while running, begins to vibrate excessively but continues to run. After shutting down the...
  46. #647 What would excessive sparking at the brushes of a running DC motor be an indication of?
  47. #648 If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist?
  48. #649 Besides checking for grounds, for what other purpose can a megohmmeter be used on a DC motor?
  49. #650 What is the most effective method of locating a loose commutator bar in a D.C. motor?
  50. #651 How may temporary repairs to an open DC propulsion armature coil be made, allowing continued operation until permanent repairs can be made?
  51. #652 When using a megohmmeter to determine which shunt field coil is grounded in a DC machine, what must you do?
  52. #653 What can be the cause of excessive heat or burning contacts in an operating motor controller?
  53. #654 The motor fails to start on an attempted startup. With the start button depressed, a voltmeter reading between 1 and 5, as in figure "A" shown in the... illustration
  54. #655 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 b... illustration
  55. #656 As shown in figure "B" of the typical ground fault relay shown in the illustration, what statement concerning the leakage current setting adjustment i... illustration
  56. #657 In order to properly set up programmable motor protection, it is necessary to know the locked rotor current of a motor. Given the chart of code letter... illustration
  57. #658 If the cooling water system is isolated for repairs, but it is still desirable to run the alternator pictured in figure "A" of the illustration, what... illustration
  58. #659 If a shipboard AC generator experiences a failure to produce a voltage, what may be the cause?
  59. #660 How can the loss of residual magnetism in an alternator or generator be corrected?
  60. #661 #1 SSDG was operating in parallel with #2 SSDG in supplying the 480 VAC main bus while sharing the electrical load evenly. As a result of a problem, i...
  61. #662 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 ma...
  62. #663 What may cause brush sparking in a DC generator during commutation?
  63. #664 Hysteresis is one cause of electrical power loss associated with electricity generation equipment. What phenomenon results in hysteresis?
  64. #665 What can cause uneven wear of the commutator surface on a direct current generator?
  65. #666 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 dif...
  66. #667 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... illustration
  67. #668 The ground indicating light on the main electrical switchboard is indicating a ground. What is the best procedure for locating the grounded circuit?
  68. #669 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 po... illustration
  69. #670 In an ungrounded distribution system, as compared to a normal indication, what is the indication on a switchboard of a current carrying conductor maki...
  70. #671 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 o... illustration
  71. #672 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 show... illustration
  72. #673 As shown in figure "A" of the ungrounded distribution system with possible ground faults shown in the illustration, under what conditions would an out... illustration
  73. #674 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 doe... illustration
  74. #675 As shown in figure "A" of the illustration, what type of ground fault detection system is illustrated? EL-0132 illustration
  75. #676 What effect will increasing the power source frequency have in a capacitive circuit?
  76. #677 Which of the procedures or conditions listed could result in damaging a transistor beyond repair?
  77. #678 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.... illustration
  78. #679 Using the trouble analysis chart and faults table provided in the illustration, if the gyrocompass was malfunctioning, but no fault codes are present... illustration
  79. #680 When troubleshooting most electronic circuits, what voltmeter characteristic can minimize the 'loading effect'?
  80. #681 Normally, what is the FIRST step in troubleshooting a transistor mounted on a circuit card?
  81. #682 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?
  82. #683 A full-wave rectifier has one diode burned out in an open condition, what will be the output characteristic of the device?
  83. #684 When troubleshooting an electronic circuit, an unreliable high resistance "cold" solder joint can be located with the aid of an ohmmeter. Once the pro...
  84. #685 On a vessel with turbo-electric drive, which of the following conditions would indicate that the propulsion motor had dropped out of synchronization w...
  85. #686 In addition to improper brush pressure or seating, what can result in excessive sparking at the brushes of a DC propulsion motor?
  86. #687 While standing an "at sea watch" onboard a modern rectified DC diesel-electric drive ship you notice the transformer core temperature slowly rising. W...
  87. #688 Refer to the diagram of the AC turboelectric drive system as shown in the illustration. The propulsion motor operates from maneuvering speed to full a... illustration
  88. #689 Refer to the simplified diagram of the AC synchronous electric motor drive system as shown in the illustration. The propulsion motor operates from man... illustration
  89. #690 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 connecte... illustration
  90. #691 Which of the following conditions will occur if the brake solenoid coil burns out on a cargo winch with an electrical brake?
  91. #692 The winch shown in the illustration operates in any of the positions with the master switch in the 'lower' direction, but will not 'hoist' in any of t... illustration
  92. #693 Refer to figure "A" representing an electric oven as shown in the illustration. With the oven turned on, the power available indicator light is off, t... illustration
  93. #694 Refer to figures "1" and "2" of the basic synchronous transmission system shown in the illustration. Figure "1" shows a properly connected system wher... illustration
  94. #695 An open primary coil in a simple potential transformer will be indicated by which of the listed conditions?
  95. #696 A 480/120 VAC step down control transformer as configured in figure "E" of the illustration produces 89 VAC across its secondary winding (across X1 an... illustration
  96. #697 The individual 12 volt lead-acid batteries, when connected as shown in the illustration, as a battery bank would produce how many volts? EL-0070 illustration
  97. #698 As shown in the illustration, the wet-cell storage batteries are connected in what configuration? EL-0071 illustration
  98. #699 What is true concerning the installation of batteries used for diesel engine starting?
  99. #700 What is the ampere-hour rating of a lead-acid battery that can deliver 20 amperes continuously for 10 hours?
  100. #701 Three 12 volt, lead-acid, batteries connected in series will develop how many volts?

Electricity questions: what to expect

Q How many Electricity questions are in the Engine pool?

There are 1,595 Electricity questions on this site, every one released by the U.S. Coast Guard or taken from the National Maritime Center's sample examinations, with its correct answer. The exam draws its Electricity module from the same pool.

Q What score do I need to pass the Electricity module?

Most USCG exam modules, including Electricity, require 70 percent to pass. Rules of the Road modules require 90 percent.

Q Are these the real USCG Electricity exam questions?

Yes. They are the published U.S. Coast Guard questions, matched to the National Maritime Center's 2026 sample examinations. Answer any question to see the correct choice, the USCG reference and the illustration where the question uses one.

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