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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 1,401–1,500 of 1,595 · page 15 of 16

  1. #1402 Figures "E" and "F" are high voltage rack mounted circuit breakers, which figure represents the circuit breaker position when in the open or tripped p... illustration
  2. #1403 How are power transformers rated?
  3. #1404 In figure "A", what is TRUE concerning the frequency response curve? illustration
  4. #1405 In figure "A", under what conditions will the thyristor conduct? illustration
  5. #1406 In order to definitively determine whether or not fuse "1" of the illustration is blown using an on-line testing technique, across what points would y... illustration
  6. #1407 If the inputs to the diagram shown in figure "2" of the illustration were A=0 and B=0, what logic levels would be indicated at points "C", "D", "E", a... illustration
  7. #1408 What type of converter unit is represented in figure "A"? illustration
  8. #1409 The conversion of the throttle command voltage to the signal necessary to achieve the desired shaft RPM is accomplished by what circuit?
  9. #1410 In the block diagram for a digitized echo sounding system, what statement is TRUE concerning the function of the transducer? illustration
  10. #1411 What is the name of the device shown in figure "1"? illustration
  11. #1412 What problem with a printed circuit board may resolve itself once a board is removed from its edge card connector and then reinstalled?
  12. #1413 When troubleshooting a printed circuit board, one technique that can be used is swapping the suspected damaged board with a new board. If a board extr...
  13. #1414 For the purposes of shipboard practice, voltages above what threshold would be considered high voltage?
  14. #1415 When a high voltage system insulation test value is suspect or recorded during an annual survey, a polarization index test is performed. What is the p...
  15. #1416 Without the benefit of a specially designed enclosure window for thermographic analysis, what must be done to obtain accurate, but safe readings using...
  16. #1417 Overheating is suspected in a high voltage bolted bus-bar joint. If the local continuity resistance is to be checked off-line after the necessary safe...
  17. #1418 What would be considered the first line of defense in trying to prevent the build-up of dust on printed circuit boards associated with computer networ...
  18. #1419 What is the name of a TCP/IP application run from the command prompt which provides routing information by determining the path through the network to...
  19. #1420 What is the name of a TCP/IP application run from the command prompt that sends datagrams once every second in the hope of an echo response from anoth...
  20. #1421 Given the digital gyrocompass functional block diagram and the associated communication protocols table, suppose the rate of turn to port signal volta... illustration
  21. #1422 In the adaptive digital steering control system functional block diagram and listed system interface signals table, if left rudder signals are negativ... illustration
  22. #1423 Use the trouble analysis chart and faults table provided. Suppose the DC/DC converter LED status indicator is functioning properly, but the CPU LED st... illustration
  23. #1424 In the illustration, if the port propulsion motor field excitation circuit experienced a failure, what individual component failure would allow the us... illustration
  24. #1425 In the diagram of figure "4", the three-phase step-down power transformer has a turns ratio of five to one. If a three-phase 4160-volt supply is conne... illustration
  25. #1426 An open primary coil in a voltage transformer (VT) will be indicated by which of the listed conditions?
  26. #1427 From the information given in the illustration, which statement is correct? illustration
  27. #1428 What will happen to the total effective circuit resistance when additional parallel circuits are added to a circuit?
  28. #1429 What type of electrical diagram for the electrical distribution system is shown in the illustration? illustration
  29. #1430 Periodic testing using a special sensing device may be performed to detect potentially dangerous loose or corroded bus bar and controller connections....
  30. #1431 To properly use a clamp-on-type ammeter for measuring current accurately, what must be done?
  31. #1432 What type of single-phase load is being tested for power measurement in figure “D” of the illustrated digital power meter? illustration
  32. #1433 When a battery-operated megohmmeter (insulation tester) is used to perform a dielectric absorption test, the resistance is measured and recorded from...
  33. #1434 In the illustrated diagnostic setup for locating a shorted field coil of a ten-pole synchronous motor, when 240 VAC/60 Hz is applied across the brushe... illustration
  34. #1435 What can be the cause of excessive heat or burning contacts in an operating motor controller?
  35. #1436 The lamp-type ground detection circuit on the main electrical switchboard is indicating a ground. When safe to do so, what is the MOST effective and p...
  36. #1437 No.1 SSDG was operating in parallel with No.2 SSDG in supplying the 480 VAC main bus while sharing the electrical load evenly. As a result of a proble...
  37. #1438 In the illustration of an electrically operated watertight door controller, how is the motor stopped automatically when the door is wedged closed? illustration
  38. #1439 What is the name of the device that works in conjunction with an automatic voltage regulator and is used as the source of magnetizing direct current d...
  39. #1440 The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts. How is this done?
  40. #1441 In the one-line distribution system diagram, if at sea the 450 VAC section of the main switchboard experiences a complete loss of power, what statemen... illustration
  41. #1442 A silicon-controlled rectifier (SCR) is a solid-state device used for what functional purpose?
  42. #1443 Regarding each of the system gateways shown in the illustration, what statement is TRUE? illustration
  43. #1444 What is the name of the mechanism used to transmit rudder angle information from the steering gear itself to the wheelhouse in the illustrated rudder... illustration
  44. #1445 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...
  45. #1446 After prior isolation and lock-out/tag-out procedures are performed, it is still possible that stored electrical energy within the circuit can pose an...
  46. #1447 In accordance with 46 CFR Subchapter J (Electrical Engineering), which of the following starting aids is the ONLY method allowed to ease the starting...
  47. #1448 By what common means is the speed of an AC propulsion motor on a diesel-electric propulsion ship controlled?
  48. #1449 In a podded azimuthing propulsion system, how is three-phase, frequency and voltage-controlled power delivered to the synchronous propulsion motor sta...
  49. #1450 Referring to the illustrated sound-powered telephone circuit, what statement is TRUE? illustration
  50. #1451 A low voltage, high current testing unit consisting of an autotransformer, ammeter, and timer may be used to test the proper tripping function of a th...
  51. #1452 In terms of the type of load in an alternating circuit, in what type of alternating current circuit will the voltage always lead the current?
  52. #1453 What is the total effective resistance of the illustrated circuit in figure "B" if the resistance of R1 is 3 ohms, R2 is 4 ohms, and R3 is 5 ohms? illustration
  53. #1454 In figure "A" of the illustration, what would be the circuit impedance if the capacitive reactance is 10 ohms and the resistance is 10 ohms? illustration
  54. #1455 While standing an "at sea watch" onboard a ship fitted with electrical propulsion motors, you notice the propulsion transformer core temperature slowl...
  55. #1456 Suppose the illustrated winch operates in any of the positions with the master switch in the "lower" direction, but will not "hoist" in any of the mas... illustration
  56. #1457 What type of rotor is most commonly used in the split-phase family of single-phase induction motors?
  57. #1458 A common type of molded case circuit breaker has both thermal and magnetic trip elements. If a branch circuit breaker has only thermal or magnetic tri...
  58. #1459 Which figure in the illustration represents a three-phase transformer connected in a wye-wye configuration? illustration
  59. #1460 How is the main propeller shaft rotation of a rectified DC diesel-electric drive normally reversed?
  60. #1461 Pertaining to an alternator protection and alarm system, what statement is TRUE concerning the component labeled "LO"? illustration
  61. #1462 In figure "C" of the illustration, what facilitates the electrical connections associated with "R1”, “R2”, and “R3" of the transmitter to "R1”, “R2”,... illustration
  62. #1463 In the illustrated circuit of figure "B", if the resistance of R1 is 10 ohms, R2 is 10 ohms, and R3 is 10 ohms, what is the total resistance? illustration
  63. #1464 When measuring DC current flow using an analog or digital multimeter set up as a milliammeter, how is the meter connected?
  64. #1465 Which of the following describes the action when the handle is moved to the "start" position of a drum-type motor controller used with a compound woun...
  65. #1466 Review the specifications in the table below. Using the provided Catalog Number Selection Chart, what is the correct catalog number for the motor star... illustration
  66. #1467 If many turns of an operating coil of an AC contactor become short-circuited, in terms of the coil, what is the likely result?
  67. #1468 In the illustration of a cycloconverter for an AC synchronous propulsion motor, what statement is TRUE concerning the operating motor frequency? illustration
  68. #1469 In figure "B" of the illustration, what statement is TRUE concerning the "regenerating operation"? illustration
  69. #1470 Referring to the illustration of a twin-screw diesel-electric AC propulsion drive system, what is the purpose of the shaft position signal? illustration
  70. #1471 Propulsion AC generators creating 4160 VAC use transformers to provide nominally 120 VAC to the automatic voltage regulator. What is the turns ratio o...
  71. #1472 How is reversal of a DC propulsion motor achieved?
  72. #1473 In a diesel-electric plant, raising the generator's field excitation current will have what effect on the DC propulsion motor speed?
  73. #1474 Refer to the simplified schematic of a two-generator, two-motor, DC diesel-electric drive propulsion system. While in two-generator, two-motor operati... illustration
  74. #1475 In the illustration of a DC diesel-electric propulsion drive system, if #1 M/E is to be secured, so that only #2 M/E diesel-generator is set up to sup... illustration
  75. #1476 Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in what types of circuits?
  76. #1477 What type of circuit is represented by the diagram in the illustration? illustration
  77. #1478 What is the purpose of the device labeled "Man-Auto Sw." in the illustrated switchboard? illustration
  78. #1479 In figure "A" of the illustration, with respect to the common equipment grounding conductor, what statement is TRUE? illustration
  79. #1480 Why is it necessary to perform periodic testing of correctly rated and properly installed circuit breakers?
  80. #1481 In figures "A", "B", and "C" of the illustration, what is the purpose of the differential amplifier segment of the 741 operational amplifier? illustration
  81. #1482 What does the circuit in the illustration represent? illustration
  82. #1483 If a digital multimeter is setup as shown in figures "A" and "B" of the illustration, what is the status of the silicon diode if the display reads 4.7... illustration
  83. #1484 When using an ohmmeter to test a semiconductor diode, you find a low resistance in both the forward and reverse bias directions. What condition does t...
  84. #1485 When troubleshooting a printed circuit board, one technique that can be used is swapping the suspected damaged board with a new board. When installing...
  85. #1486 When troubleshooting a printed circuit board, one technique that can be used is component substitution. Upon what basis would a suspected defective co...
  86. #1487 In the block diagram for a digitized echo sounding system, what statement is TRUE concerning the transmission and reception of acoustical energy? illustration
  87. #1488 In the adaptive digital steering control system functional block diagram and listed system interface signals table, if left rudder signals are negativ... illustration
  88. #1489 Referring to figure "B", what statement is TRUE? illustration
  89. #1490 What statement is true concerning the total resistance of a parallel circuit?
  90. #1491 The illustration depicts a steering control system. What type of electrical diagram is it? illustration
  91. #1492 A resistance is added in series and internally with the analog meter movement of which of the following instruments?
  92. #1493 When configuring a digital multimeter as an ohmmeter, what will MOST likely be displayed on the screen when the test leads are shorted together?
  93. #1494 What is an ammeter used to measure?
  94. #1495 Why should battery rooms be well ventilated during the charging of lead-acid storage batteries?
  95. #1496 Why are nickel-cadmium batteries superior to lead-acid batteries for standby service?
  96. #1497 What is the nominal output voltage of a 6-cell lead-acid battery?
  97. #1498 What type of motor and motor starter are featured in the illustration? illustration
  98. #1499 What is the function of the movable cams in a master-switch winch motor drum controller?
  99. #1500 Referring to the containership one-line distribution diagram, what is the purpose of the transformers providing power to the refrigerated container fe... illustration
  100. #1501 The diagram in figure "B" represents what type of transformer? illustration

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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