Assessment Test

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1. When a resistor is used as a shunt and is connected in parallel with a meter movement coil, what capability does this provide?

 
 
 
 

2. Which of the following electric meter movements uses a stationary permanent magnet and movable coil?

 
 
 
 

3. To limit the current flow through a DC voltmeter to as low a value as possible, what is the moving coil circuit provided with?

 
 
 
 

4. What is the instrument called a galvanometer used to measure?

 
 
 
 

5. How is a wattmeter electrically connected in a circuit?

 
 
 
 

6. In testing a hand cranked megger prior to use, what statement is true?

 
 
 
 

7. Prior to using an analog multimeter set up as an ohmmeter, the leads are purposely shorted together. Which of the following actions should be taken if, when adjusting to 'zero' ohms, the indicating needle cannot be returned to 'zero' on the scale?

 
 
 
 

8. While troubleshooting a circuit in an engine room central control console, a resistor is suspected of being faulty. Which of the following precautions must be observed if an analog or digital multimeter set up as an ohmmeter is to be used to check its value?

 
 
 
 

9. If you disconnect and arrange both ends of a conductor of a multi-conductor cable without any contact between the individual conductors, what would a low ohmic value between the ends of a single conductor indicate?

 
 
 
 

10. Which of the listed statements is correct when using an digital multimeter set up as an ohmmeter?

 
 
 
 

11. 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 discharged capacitor in good condition?

 
 
 
 

12. 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?

 
 
 
 

13. Under what circumstance would a hand-held portable phase sequence indicator be used should the main switchboard mounted fixed phase sequence indicator be inoperative?

 
 
 
 

14. In what situation would an electrical phase sequence indicator be useful?

 
 
 
 

15. Which of the listed battery charging circuits is used to maintain a wet-cell, lead-acid, storage battery in a fully charged state during long periods of disuse?

 
 
 
 

16. What will be the freezing point of the electrolyte in a fully charged lead-acid battery as compared to a discharged battery?

 
 
 
 

17. What should be performed as routine maintenance of lead acid batteries?

 
 
 
 

18. Which of the processes listed occurs during the charging of a lead-acid storage battery?

 
 
 
 

19. To test the state of charge of a nickel-cadmium battery, what should be used?

 
 
 
 

20. Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?

 
 
 
 

21. What is the standard procedure for maintaining the charge in an emergency diesel starting battery by trickle charge?

 
 
 
 

22. Which of the substances listed should be applied to battery terminals to help prevent corrosion?

 
 
 
 

23. What is practice is considered conducting proper storage battery maintenance?

 
 
 
 

24. 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.

 
 
 
 

25. What would cause a lead-acid battery to become hotter than normal during charging?

 
 
 
 

26. When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?

 
 
 
 

27. Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?

 
 
 
 

28. After a black out onboard and once ships power has been restored, the engine room supply fans must be started manually. What characteristic of the electrical circuit for the supply fans cause this requirement?

 
 
 
 

29. What is the advantage of using an auto-transformer starter?

 
 
 
 

30. What is the advantage of using a star delta starter?

 
 
 
 

31. If a motor is direct-on-line started with the stator winding star connected, it will only take a fraction of the starting current that it would take if the windings were delta connected. What is that fraction?

 
 
 
 

32. You direct the electrician to take quarterly insulation resistance reading of the ship's critical motors. What additional directions would you give to ensure accurate readings are taken that will allow for the logical comparison of prior and current readings?

 
 
 
 

33. (The design Power Factor (PF) of a vessel's electrical system is generally 0.8 - 0.9. The system's greatest load is inductive. One notices a slow, gradual decrease, over time, in the PF, from normal/design. What can one do on board to maintain the normal, design PF and thus maintain electrical system's efficiency?

 
 
 
 

34. The electrical officer is about to check the insulation resistance. When advice should you give to him as to what temperature and or when he should check the motor insulation?

 
 
 
 

35. When testing the rotor of a synchronous motor for short circuits, a low voltage source is applied across the rotor coils through the collector rings. What would be the indication of a short- circuited coil?

 
 
 
 

36. If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open), what would be the result?

 
 
 
 

37. What would be the most likely fault if a single-phase permanent split capacitor induction motor fails to start?

 
 
 
 

38. In testing a three-phase delta-connected winding for an open circuit using a ohmmeter, what must be done?

 
 
 
 

39. What would happen if the centrifugal switch or relay, for cutting out the starting winding of a split-phase induction motor, failed to open while the motor was in operation?

 
 
 
 

40. How may temporary repairs to an open DC propulsion armature coil be made, allowing continued operation until permanent repairs can be made?

 
 
 
 

41. What can insufficient brush pressure on a DC motor cause?

 
 
 
 

42. Which of the listed colors properly describes a DC motor commutator when correct commutation is taking place?

 
 
 
 

43. If a short circuit in the armature of a DC motor occurs what would be the result?

 
 
 
 

44. An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. What would be the next step in troubleshooting this problem?

 
 
 
 

45. How is a short in the shunt field of a DC motor best located?

 
 
 
 

46. Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars?

 
 
 
 

47. By what means is the rotation of a three-phase induction motor reversed?

 
 
 
 

48. A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the motor from being damaged?

 
 
 
 

49. With what kind of starting equipment are most three-phase induction motors of five horsepower or less started?

 
 
 
 

50. Which of the following statements is true concerning the cleaning of electrical contacts?

 
 
 
 

51. By what means should motor controller contacts be routinely cleaned?

 
 
 
 

52. What item (or items) constitute routine AC motor controller maintenance?

 
 
 
 

53. Before working on an electric cargo winch master switch or controller, what should be done?

 
 
 
 

54. What damage may occur to the components of a winch master control switch, if the cover gasket becomes deteriorated?

 
 
 
 

55. If the contacts of a motor starter or controller fail to drop out when the 'stop' button is depressed, what could be the cause?

 
 
 
 

56. What may cause magnetic controller contacts to become welded together during operation?

 
 
 
 

57. Power conversion for use in DC propulsion drive motors is accomplished by what type of converter?

 
 
 
 

58. The conversion of constant frequency power into adjustable frequency power in a modern AC propulsion drive system is commonly achieved through the use of what electronic system components?

 
 
 
 

59. Which of the following statements is true concerning a large polyphase synchronous main propulsion motor as used in an electric propulsion drive system?

 
 
 
 

60. Which of the following is a disadvantage of electric drive propulsion systems?

 
 
 
 

61. What statement is TRUE concerning the Azipod propulsion system?

 
 
 
 

62. Which of the following statement is TRUE concerning Azipod propulsion systems?

 
 
 
 

63. How is the main shaft rotation on an AC diesel-electric propulsion vessel normally reversed?

 
 
 
 

64. How is the direction of propeller shaft rotation changed when directly coupled to an AC synchronous motor when driven by a variable frequency alternator in an AC turbo-electric drive system?

 
 
 
 

65. How is the direction of rotation of the main propulsion motor in a modern AC propulsion drive system reversed?

 
 
 
 

66. How is the speed of the propeller shaft directly coupled to an AC synchronous propulsion motor changed when powered by a variable frequency alternator in an AC turboelectric drive system?

 
 
 
 

67. What statement is TRUE concerning the speed of a synchronous ac propulsion motor?

 
 
 
 

68. By what common means is the speed of the AC propulsion motor on a diesel- electric propulsion ship controlled?

 
 
 
 

69. A common method used to control the speed of a synchronous AC propulsion motor on a diesel-electric propulsion drive is by what means?

 
 
 
 

70. Which of the listed temperature measuring devices installed on a large turbo-electric alternating current propulsion generator would be the most reliable for monitoring generator temperatures to avoid premature winding insulation failure?

 
 
 
 

71. Which of the listed devices is most likely to be installed on a large modern diesel- electric alternating current propulsion generator for commercial ship propulsion for the purposes of fire suppression?

 
 
 
 

72. Propulsion AC generators creating 4160 VAC use transformers to provide nominally 120 VAC to the automatic voltage regulator. What is the turns ratio of this step-down transformer?

 
 
 
 

73. An electric propulsion drive system in which the propulsion generator supplies power to both the propulsion motor and ship service loads is referred to as what type of system?

 
 
 
 

74. An electric propulsion drive system in which the propulsion generator only supplies power to the propulsion motor is referred to as what type of system?

 
 
 
 

75. In addition to improper brush pressure or seating, what can result in excessive sparking at the brushes of a DC propulsion motor?

 
 
 
 

76. 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?

 
 
 
 

77. 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?

 
 
 
 

78. 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?

 
 
 
 

79. What equipment for modern SCR rectified DC propulsion drive systems is usually included in the package?

 
 
 
 

80. How are fuses usually rated?

 
 
 
 

81. Due to the operating characteristics of the system, time lag fuses (or dual-element fuses) are necessary for use in what types of circuits?

 
 
 
 

82. What is the characteristic that is associated with an "instantaneous-trip" single- element type fuse?

 
 
 
 

83. Fuses are sometimes placed in series with a thermal trip-type circuit breaker. What is the purpose of a fuse used in this arrangement?

 
 
 
 

84. In a dual element time-delay cartridge-type fuse, what type of protection is provided for motor applications?

 
 
 
 

85. A fuse is the most common type of protection against a short-circuit fault in LV distribution circuits, motor circuits and for portable appliances. What is a major drawback or deficiency with the use of fuse?

 
 
 
 

86. By what means does a molded-case breaker provide protection against short circuits?

 
 
 
 

87. When the operating handle of a molded-case circuit breaker is in the mid-position, what does this indicate?

 
 
 
 

88. What is a bus disconnect link used to isolate?

 
 
 
 

89. What is meant by the term 'dielectric'?

 
 
 
 

90. What is the greatest single cause of electrical failures?

 
 
 
 

91. What is a common type of protective covering used on electrical conductors?

 
 
 
 

92. What are the operating characteristics of a step-down potential transformer in terms of the secondary load?

 
 
 
 

93. Which of the listed transformers uses a single winding to produce voltage transformation?

 
 
 
 

94. What is the function of the autotransformers used with autotransformer starters used on some large AC motors?

 
 
 
 

95. An electrical component is connected across a 120 volt 60 hertz AC supply. What is the current drawn by the component if the impedance is 200 ohms?

 
 
 
 

96. 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 of transformer. Which type is used?

 
 
 
 

97. To properly use a clamp-on-type ammeter to check current flow, what must be done FIRST?

 
 
 
 

98. How should the shunt used in an ammeter be connected?

 
 
 
 

99. Why are external shunts sometimes used with ammeters?

 
 
 
 

100. What is an ammeter used to measure?

 
 
 
 


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