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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 1,501–1,595 of 1,595 · page 16 of 16

  1. #1502 A thermal-magnetic molded case circuit breaker for a 300-kW alternator is rated at 500 amperes at full continuous load. Which of the following conditi...
  2. #1503 What property of a material is rated in voltage per millimeter (V/mm) of insulation thickness that the insulation can withstand without breaking down?
  3. #1504 What type of logic circuit is represented in all four diagrams shown? illustration
  4. #1505 What is the function of the Zener diode "CR1" shown in section "D" of the regulated DC power supply? illustration
  5. #1506 A voltage amplifier has a calculated voltage gain of 5. Which statement is true concerning input and output voltages?
  6. #1507 Ships requiring extremely rapid maneuvering response using propeller shaft speed and direction as the sole means of controlling propeller thrust are m...
  7. #1508 Given the diagram in figure "A", how many pulses does the load-commutated inverter drive have? illustration
  8. #1509 A bearing temperature monitoring system such as that used for measuring selected propulsion plant bearings uses what technology?
  9. #1510 In the block diagram for a distributed automation system, and concerning the workstations labeled "LOS" associated with the port power management syst... illustration
  10. #1511 In the diagram, when the master switch handle is moved away from the "off" position, what is responsible for maintaining the "UV" relay energized? illustration
  11. #1512 Which of the listed conditions occur when selection is made for "third point hoist" on the winch hoist controller shown in the illustration? illustration
  12. #1513 What type of motor is used in the illustrated AC hoist controller? illustration
  13. #1514 You are replacing a three-phase induction motor in an application where equipment could be damaged if the direction of rotation of the motor is incorr...
  14. #1515 Which of the conditions listed will indicate the need to clean the insulation on the stator windings of an alternating current induction motor?
  15. #1516 In figure "A" of the illustration, what phenomenon is depicted with respect to electrical cable conductors and hull ground? illustration
  16. #1517 Which of the following methods should be used to dress the face of silver-plated contacts?
  17. #1518 When you are making a high potential test (insulation resistance) on the motor coils of repaired electrical machinery to ground, what would a low resi...
  18. #1519 Contact with any energized electrical system conductor is potentially hazardous and precautions should be taken to prevent exposure. With all other fa...
  19. #1520 In a series circuit, what is the applied voltage (or sum of the applied voltages) equal to?
  20. #1521 In figure "A", with the switch closed, if "R1" and "R2" have unequal resistance values, what statement is TRUE? illustration
  21. #1522 In a simple DC circuit consisting of one resistive load, the resistance is held constant while the applied voltage is halved. What will be the effect...
  22. #1523 Which statement is TRUE regarding figure "6" of the illustration? Illustration EL-0026 EL-0026.jpg illustration
  23. #1524 What does the symbol in figure "6" of the illustration represent as used in electrical drawings? illustration
  24. #1525 As shown in figure "A" of the illustrated digital multimeter screen, what would be the significance of the symbol indicated by "1" being illuminated? illustration
  25. #1526 The motor of the illustrated motor controller fails to start on an attempted startup. You ensure the motor has not tripped out on overload, and you ch... illustration
  26. #1527 Suppose an ungrounded 3-phase distribution system is fitted with a lamp-type ground detecting circuit with 3 lamps. If an accidental ground is display...
  27. #1528 In the illustrated wound-rotor induction motor, what statement is TRUE concerning motor lead connections? illustration
  28. #1529 What is the functional purpose of a generic electromagnetic relay?
  29. #1530 In which of the following branch circuits would time lag fuses (or dual-element fuses) be MOST likely used?
  30. #1531 What is the purpose of a three-phase lighting power transformer bank of a shipboard distribution system?
  31. #1532 Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?
  32. #1533 What is the name of the semiconductor device with the essential characteristic that it decreases in resistance with an increase in temperature?
  33. #1534 In referring to figure "A", what type of active filter circuit is shown? illustration
  34. #1535 What type of motor is generally used in DC propulsion drive systems?
  35. #1536 In the block diagram for a distributed automation system, and concerning the remote operating system workstations labeled "ROS", what statement is TRU... illustration
  36. #1537 What statement is true concerning the charging of a 100 amp-hour lead-acid battery?
  37. #1538 Suppose it is desired to connect a dual voltage three-phase squirrel-cage induction motor for low volts, but it is undetermined whether the nine-lead... illustration
  38. #1539 Which of the following devices would be forbidden to use as a primary means of electrical isolation?
  39. #1540 An unintended path of low resistance bypassing the intended path and allowing passage of an abnormally high amount of current is known as what?
  40. #1541 Four incandescent lamps are connected in series in a single circuit. If one of the lamp filaments burns out, what will happen to the other lamps?
  41. #1542 How is the power dissipated as heat in a simple direct current circuit consisting of one resistive load calculated?
  42. #1543 What is an ohmmeter used to measure?
  43. #1544 In what situation would an electrical phase sequence indicator MOST likely be useful?
  44. #1545 What is the most practical method of controlling the RPM of a multi-speed AC motor operating at a constant frequency?
  45. #1546 In preparing a battery-operated digital megohmmeter (resistance tester) for use, what statement is true?
  46. #1547 What configuration are the illustrated wet-cell storage batteries connected in? illustration
  47. #1548 In figure "A" of the illustration, what does the three-phase drive motor, labeled as "M-G set", mechanically drive? illustration
  48. #1549 In figure "A" of the illustration, what devices does the rudder angle repeat back signal originate with and return to? illustration
  49. #1550 Which of the following statements represents the main difference between an electromagnetic relay and an electromagnetic contactor as used in motor co...
  50. #1551 What is the primary means by which an electrical maintenance worker is protected from electrical hazards while performing work on an electrical circui...
  51. #1552 Which figure in the illustration represents a magnetic reversing or two-speed motor starter? illustration
  52. #1553 When shore power is being connected to a ship in dry-dock, what must be ensured, assuming that the ship's generators are rated at 450 VAC, 60 Hz with...
  53. #1554 In which of the following branch circuit types would time lag fuses (or dual-element fuses) be MOST likely used?
  54. #1555 When placed in a magnetic field, which of the materials listed has the highest permeability?
  55. #1556 In what applications are semiconductor diodes commonly used?
  56. #1557 What purpose does the component labeled "CR1" serve in the illustrated circuit? illustration
  57. #1558 In referring to the frequency response filters in the illustration, what determines the band pass or band stop frequencies as appropriate? illustration
  58. #1559 Which of the following fixed temperature heat-actuated fire detectors can be reused after it has detected a fire?
  59. #1560 Refer to the illustration pertaining to the semi-automatic navigation light panel circuit. If the buzzer sounds and the masthead indicator light comes... illustration
  60. #1561 Referring to the impressed current cathodic hull protection system in the illustration, if required to control the impressed current to the anodes man... illustration
  61. #1562 Referring to the containership one-line distribution diagram, what statement is TRUE concerning the battery charger? illustration
  62. #1563 In preparation for paralleling generators, if the US built, US Flag vessel electric plant condition is as shown by graph "A", what would be the rotati... illustration
  63. #1564 What is the correct methodology to prevent shaft currents in an alternator?
  64. #1565 To prevent shaft currents in an alternator, the outboard bearing shell or outboard bearing pedestal is insulated. If the methodology used is the insul...
  65. #1566 As shown in the alternator protection scheme diagram, what device provides the input to the overcurrent inverse time relay "OCIT", the overcurrent ins... illustration
  66. #1567 The illustration shows a diagnostic setup for locating a shorted field coil of a ten-pole salient pole alternator. Suppose the No. 4 field coil had sh... illustration
  67. #1568 What type of overload relay for motor protection is illustrated in figure "B"? illustration
  68. #1569 In the illustration, what mechanism will disconnect the motor from the line in case of a sustained motor overload? illustration
  69. #1570 How is the main propeller shaft rotation of a conventional AC turbo-electric drive normally reversed? (Assume that no converters or inverters are used...
  70. #1571 Referring to the illustration of a DC diesel-electric drive system, what type of DC propulsion motors are used? illustration
  71. #1572 On DC diesel-electric drives, how is the speed of the DC propulsion motor primarily controlled?
  72. #1573 (3.1.10.1.6-1) What is the purpose of the device labeled "Man-Auto Sw." in the illustrated switchboard? illustration
  73. #1574 A resistance in a circuit of unknown value is to be tested using the voltmeter/ammeter method. How should the two meters be connected?
  74. #1575 As shown in figures "B" and "C", if your intent is to measure AC currents anticipated as high as 5 amps, what should be the switch position, and which... illustration
  75. #1576 Which electrical schematic symbol represents a normally closed flow switch? illustration
  76. #1577 Which illustrated resistor represents the schematic symbol shown in figure "B"? illustration
  77. #1578 In figure "B", if the source voltage at the branch circuit breaker is 220 VAC, what would be the applied voltage to the load? illustration
  78. #1579 What is the function of the circuit shown in section "C" of the illustration? illustration
  79. #1580 Which of the listed devices may be used as a digital device?
  80. #1581 For troubleshooting purposes, the key indicator to the safety and general condition of high voltage circuitry is insulation resistance. For a 6.6 kV h...
  81. #1582 When troubleshooting the modems, network interface cards, hubs, switches, and routers of a network, what technique represents the most logical first s...
  82. #1583 What would be an ideal location when mounting a transducer for a depth sounding system?
  83. #1584 When the compressed air reservoir is placed in line with an air compressor and is used as an aftercooler, what must be done with the reservoir?
  84. #1585 In general, what type of starter would be used to connect a three-phase induction motor to full line voltage at the instant of start-up?
  85. #1586 Which of the following methods should be used to test for an 'open' stator winding coil in a wye-connected AC squirrel cage induction motor?
  86. #1587 If you hear the general alarm sounded 3 times supplemented by 3 short blasts of the whistle, what does this indicate?
  87. #1588 How much is the nominal open-circuit voltage of one cell of a fully charged lead-acid battery?
  88. #1589 What is the combined effect of inductive reactance, capacitive reactance, and resistance in an alternating current circuit known as?
  89. #1590 If an attempted light off of an idle boiler fails, what should be done?
  90. #1591 Which of the following statements represents the important factor that must be considered when replacing a faulty diode in a generators excitation fie...
  91. #1592 If a sea water-cooled shell-and-tube lubricating oil cooler has the sea water inlet and outlet connections on the opposite end waterboxes, in terms of...
  92. #1593 In comparing a semiconductor diode to a vacuum tube diode, what statement is true?
  93. #1594 For what purpose are time delayed or delayed action-type fuses used?
  94. #1595 The illustrated drawing shows a correct front "F" and top "T" view of an object. Of the views labeled "1","2","3", and "4", the one that correctly rep... illustration
  95. #1596 In a three-phase, squirrel-cage type, induction motor, how is the primary rotating magnetic field established?

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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