Competence 6

146問 • 2ヶ月前

問題一覧

1. What will happen if a low impedance connection is accidentally created across a charged capacitor within a high-voltage electrical network?

•Large amounts of power can be quickly discharged.

2. When troubleshooting an electronic circuit, a cold solder joint can be located with the aid of an ohmmeter. Once the problem has been located, what should you do next?

•reheat connection with a soldering tool and recheck with an ohmmeter

3. What kind of overload relay that is being actuated by an electromagnetic coil ?

•Magnetic

4. What kind of resistance thermometer utilizes semi-conductor material which have a characteristic of a resistance decrease with temperature increase?

•Thermistor

5. What is the ratio of effective value of the counter EMF in volts to the effective value of the current in amperes?

•inductive reactance

6. The amount of sodium phosphate in treated boiler water can be measured by ?

•Phosphate test

7. What determines the power factor of an electrical distribution system being supplied by a single AC generator?

•By components of the connected load,

8. An instantenous trip type fuse will ?

•open as soon as the loadcurrent exceeds the set point

9. What is the transformer winding where power source is connected?

•Primary winding

10. When a solid-state component of an electronic circuit is mounted to a metalic mass, the general purpose of that mass is to

•act as a heat sink

11. A bus disconnect link is used to isolate?

•the generator ccircuit breaker from the bus

12. After clipping the two leads together, prior to taking a resistance reading with a volt-ohmmilliammeter, the 'zero' setting must be adjusted. ylf you find the adjustment knob will not return the pointer to 'zero'. it is likely an indication of ?

•Batteries are weak

13. Electric propulsion coupling excitation is reduced at slow speed to

•prevent coupling overheating

14. Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation ?

•The winding will burn out.

15. What do you call the emission of electrons from hot bodies?

•radiation effect

16. Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?

•Increase ambient temperature decreases the service life of electronic components

17. The first requirement for logical trouble shooting of any system is the ability to

•recognize normal operation

18. What is the use of a magnetic blowout coil in a ship,s crane using DC motor controller contactor ?

•prevent contact melting

19. In SF6 circuit breakers what is the meaning of SF6?

•Sulfur hexafluoride

20. When trouble shooting electronic equipment, you should use a high impedance multimeter

•so as not to load down the circuit and obtain erroneous voltage readings

21. How would you show your understanding to a communication device that allows to talk to each other with the use of a handset, similar to a conventional telephone but without the use of external power?

•Sound-powered teelephone system

22. In a liquid dielectric, which of the following impurity has significant effect in reducing the breakdown strength ?

•Dust

23. A loss of field excitation to an AC generator while operating in parallel will cause to

•lose its load, begin to motorize, trip out on reverse power delay, and possibly overspeed

24. On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive over travel of the pilot valve by the synchronous motor. These devices are called_

•limit switches

25. In a faceplate-type motor starter, the starting arm is held in the 'OFF' position by alan

•strong spring

26. The shunt use in an ammeter should be connected to?

•series with the load and in parallel with the meter movement

27. Which of the following statements concerning analog and digital devices are correct?

•The variables in digital systems are fixed quantities, and the variables in analog systems are contnuous quantities

28. What do you call an instrument that used to measure the specific gravity of the electrolyte in a rechargeable battery ?

•Hygrometer

29. To locate a grounded field coil in a synchronous motor, which of the instruments listed could be used ?

•Megohmmeter

30. You are attempting to parallel two AC generators, and the synchroscope pointer is revolving past in the clockwise direction. What indicates that the frequency of the incoming machine?

•higher than the bus frequency

31. It is defined as the movement of electrical charge (the flow of electrons) through an electrical circuit is called ?

•Current

32. What represents an application of a silicon controlled rectifier?

• To provide DC power for a main propulsion motor.

33. In a circuit that is not energized, which of the listed instrument is used ?

•Ohmmeter

34. How is the operator ensured that he is not in contact with any unearthed conductor before insulation resistance(IR) measurement of a HV system?

•Connct the insulation resistance tester to the conductor with safety earth connection ON.

35. What is the process of breaking up fuel oil into fine particles to ensure good combustion?

•Atomization

36. How do shipboard electrical cables cross-sectional area express?

•circular mills

37. RTD type sensor utilizes which principle in temperature measurement?

•Wheatstone bridge principle

38. What is the first step in removing a generator from parallel operation.

•Decrease the governor setting on the l'off goingl' generator.

39. Which of the following indicate when paralleling two alternators, the synchronizing lamps remain lit as the synchroscope pointer approaches the 0° position?

•synchroscope is defective or broken

40. What cause the main feed pump which can handle high temperature water without becoming vapor bound?

•Required net positive suction pressure is designed into the system

41. What is the degree angle when the voltage and current are out of phase so that the true power is equal to zero?

42. The following are main things you should ccheck when synchronizing a generator except for?

• current

43. What type of widely used thermocouple, also termed as Ni-Chromium/Ni-Alumel, with enhanced reliability, preciseness, inexpensive and operate at temperature ranges between -270 to 1,260 degc?

•Type к

44. Ammeters and voltmeters use in a sinusoidal AC power system indicates which of the following values of the waveforms measured?

•root means square value

45. The following are rating of circuit breakers except

•Rated short ionization current

46. a triac thyristor functions as a control device and is basically

•two-back-to back SCR's with a common gate lead

47. In a three-phase electrical system, three ground detecting lamps are provided. One lamp goes dark and the others increase in brightness. When the test button is pushed, all lamps have equal illunination. You should called that

•There is a ground on the line with the dark lamp

48. While starting a synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. What is this an indication of?

•motor has started properly

49. When using an ohmmeter to test a semi conductor diode, you find a low resistance in both forward and reverse bias direction. This indicates that the diode is,

•Short

50. On a vessel with turbo-electric drive, which of the following conditions would indicate that the propulsion motor had cut-out from synchronization with the propulsion generator ?

•Excessive vibration of the vessel

51. A field effect transistor function that reduces number of current carries passing through its channel

•depletion mode

52. Which of the listed pairs of materials make the best insulators ?

•glass and mica

53. All portable electric tools should have a ground connection to prevent ?

•electric shock if the tool is shorted

54. The governor control switch of an alternator is move to the raised position. This action will

•raise the no-load speed setting of the governor

55. Which of the following statements is correct concerning the circuits in a sound powered telephone system?

•The common talking circuit is composed of two ungrounded wires

56. When trouble shooting electronic equipment, you should use a high impedance multimeter.

•so as not to load down the circuit and obtain erroneous voltage readings

57. The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the

•alternator field excitation

58. When trouble shooting electronic equipment, the first step to be taken before testing the circuit voltage i

•check the voltage supply from the power source

59. What device that gives the information about the speed of a motor in D.C. Generator?

•Speedometer

60. A ship is generating 8MW of power at 440V from 4 diesel generator of 2MW 0.8 power factor each. How much full-load current each generator feeder cable and circuit breaker be able to handle?

•3,280 Amperes

61. It is a type of motor that is almost the same as an alternator .

•Synchonous motor

62. To minimize magnetic field interaction between electrical conductors in physical proximity, it is best to keep them?

•at right angles and as far as practicable

63. To be considered as High Volatge system used on board a ship, how much should be the minimum voltage?

• 1,000V

64. The magnetic energy of a transformer when created will further induced current in the ?

•secondary winding

65. When the voltage and current developed in AC circuit reached thier peak value at the same time, the power factor is?

•maximum

66. In general, polyphase induction motors can be started on full line voltage by what means?

•across-the-line starters

67. What do you call a conductor carrier opposite to the majority current carrier which are represented by the holes in n-type material and free electrons in p-type material?

•Minority current carrier

68. What is being used to indicate whether the alternator is running faster or slower than the other. What is this device installed in the main switchboard?

•Synchroscope

69. When trouble shooting most electronic circuits, "loading effect" can be minimized by using a volt volt meter with alan

•input impedance much greater than the impedance across which the voltage is being measured

70. On a vessel with turboelectric drive, which of the following conditions would indicate that line propulsion motor had dropped out synchronization with the propulsion generator?

•Excessive vibration of the vessel

71. Which of the stated pressure conditions identifies the boiler design pressure?

•The pressure specified by the manufacturer as a criteria for boiler design

72. Regarding and AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in armature reaction are compensated for by the

•voltage regulator

73. Which of the following is developed whenever there is a relative motion of action between a magnetic field and a conductor ?

•electromotive force

74. Four lamps are connected in parallel in a single circuit. If one of the lamp burns out, theothers will

•burn with their original intensities

75. A closed loop control system which enables two or more valves operated by one controller is known as

•split range control

76. On some diesel-electric ships, the DC propulsion motor will only attain half speed when the generator fields are fully excited. Speeds above this are obtained by?

•raising the generator engine speed

77. Which of the following may cause a single-phase induction motor fails to start?

•an open in the main winding

78. A ship is generating 8MW of power at 440V from 4 diesel generator of 2MW 0.8 power factor each. How much full-load current each generator feeder cable and circuit breaker be able to handle? Option 1(ANSWER): 3,280 Amperes Option 2: 4,050 Amperes Option 3: 1,500 Amperes Option 4: 2,850 Amperes

•3,280 Amperes

79. Which of the following statement is true concerning a step-down transformer in an operating AC power circuit?

•Voltage decreases as current increases

80. Why is corrosion due to electrolytic action in modern water-tube boilers is uncommon?

•Boiler components are generally constructed of similar metals

81. Listed are the types of circuit breakers except?

•Ceramic circuit breaker

82. Which of the following refers to a characteristics of a magnetic line of force?

•it travels from north to south through the surrounding medium of bar magnet

83. Which of the following values of the waveforms measured in ammeters and voltmeters?

•root means square value

84. When trouble shooting an electronic circuit, a cold solder joint can be located with the aid of an ohmmeter. Once the problem has been located , you should,

•reheat connection with a soldering tool and recheck with an ohmmeter

85. Two paralleled alternators are operating near rated load. If one trips out mechanically, which of the listed actions should be taken first?

•Strip the board of all nonvital circuits.

86. Ships fitted with high-voltage installations tend to use earthed neutral electrical networks. Which one of the following best describes how excessive fault currents are prevented in the event of an earth fault on these ships?

•Impedance is placed in neutral earthing line.

87. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called,

•Zener diodes

88. A ground on a particular phase of a three phase low voltage system would be indicated by ?

•dark or dim switchboard ground detectinglight

89. How can the hot spots in the bus bar or surrounding area be checked safely?

•By using infra-red thermal imaging device

90. In electronic industry, the abbreviation "PCB" commonly means

•Printed circuit board

91. What do you call a direct current passing through a wire coiled around a soft iron core?

•electromagnet

92. In synchronizing a generator with other generator, it is required that the voltage and frequency of the incoming generator is

•Equal voltage, equal frequency

93. Equal power factors on paralleled AC generator are maintained by an automatic

•voltage regulator

94. When electrocuted, how much current may lead to loss of muscular control?

•25 mA

95. Which of the following refers to a characteristics of a magnetic line of force ?

•it travels from north to south through the sorrounding medium of bar magnet

96. What do you call a motor using a rheostat in the motor circuit to vary the speed?

•wound-rotor induction motor

97. What is the part of the shipboard electrical system used to control the distribution of power to the branch circuit?

•main switchboard

98. What is the main reason in using an electronic megger tester essentially for polarization index or Pi test.

•Because hand driven megger tester will not be able to give the steady test voltage for longer time

99. To provide its unique characteristics to analog circuits, the operational amplifier is made up of alan

•differential amp, voltage amp and output amp

100

100. What would you obtain if you measure voltage and current in an inductive or capacitive circuit and then multiply them together?

•apparent power

Competence 1

Emm · 112問 · 2ヶ月前

Competence 1