competence 7.1

60問 • 1年前

問題一覧

1. Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by_

feeding current into the windings at low voltage

2. What precaution should be taken with a vessel's impressed current cathodic protection system after a drydocking period during which the hull has been painted?

The unit should remain off for the specified amount of time so as not to disturb curing

3. The schematic symbol for an operational amplifier in an analogue circuit is a

Triangle

4. A three-phase squirrel-cage induction motor will run hot due to

Open stator coils

5. A capacitor can be tested using a megohmmeter or an ohmmeter, if the meter is connected to a shorted capacitor, the meter pointer should_

immediately deflect to and remain at zero

7. A switchboard for an AC electrical system requires the use of which of the following devices?

Frequency meter

8. When changing tubular fuses always use a

Fuse puller

9. The greatest single cause of electrical failure is

The breakdown of insulation

10. What will you do if the generator is exposed to rain or any water?

Make a megger test

11. A safety device in an electrical circuit consisting of metal strip that melts when the current exceeds the safe level is called

fuse

12. An electric tachometer receives the engine speed signal from?

bimetallic sensing device

13. A current at which a magnetic-type overload relay tends to trip maybe decreased by raising the plunger further into the magnetic circuit of the relay. This action will

Increases magnetic pull on the plunger and requires less current to trip the relay.

14. What does the variable resistance placed in the rotor circuit of a wound-rotor induction motor provide?

speed control

15. What kind of instrument used to measure the specific gravity or "charge" Of the electrolytes of a storage battery?

hydrometer

16. Which of the following materials is recommended for finishing the slip rings after grinding or turning?

crocus cloth

17. What kind of device that has two pieces of metal joined together so that when its junction is heated, a voltage is produced?

Thermocouple

18. When removing ball or roller bearings from the shaft of a motor, you should use a

wheel puller

19. What do do you call on a periodic testing by a shore side support technician using a special camera which can detect potentially dangerous loose or corroded bus bar and controller connections?

heat sensitive thermography

20. When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered.

in parallel

21. What motor is fitted with an instantaneous overload relay?

Winch

22. If both the "high level and "low level''alarms come on for the same address of a centralized control console, the most likely problem is alan

sensor failure

23. Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?

Place heat lamps in the motor housings.

24. A common type of protective covering used on electrical conductors is

fibrous braid

25. When a nickel-cadmium battery begins gassing while connected to the battery charging circuit, you should

do nothing as this is a normal condition when charging

26. A molded-case breaker provides protection against short circuits by using ?

electromagnet

27. What may happen to the components of a winch master control switch, if the cover gasket becomes deteriorated?

Rapid corrosion of switch components.

28. What should you use to determine if a stator coil is grounded?

megger

29. The charging of lead-acid storage batteries will always result in ?

a dangerously explosive gas being liberated

30. With both ends of a three conductor cable disconnected and arranged without the conductors touching each other, an ohmmeter reading of 'zero' ohms between the ends of one conductor would indicate

continuity

31. What is a device that changes an input signal of one type into an output signal of a differnt type that is proportional to the original input?

Transducer

32. What gives the information about the speed of a motor in D. C. Generator, ?

Speedometer

33. To check the three line fuses of three-phase system consisting of a three-phase motor, you must

make sure the motor is operating at full load to guard against a false reading

34. periodic testing of circuit breakersis necessary to assure that a correct rated and properly installed unit

will continue to provide the original degree of protection

35. How should controller contacts be routinely cleaned?

wiping with a clean dry cloth

36. Which of the following safest precautionary measure is to be done prior working on the motor of the cargo winch?

Switch off main switch and put sign do not switch on.

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

burn with their original intensities

38. Electrical leads and insulation on a motor should be painted with

insulating varnish

39. Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel-cage motor does not?

Slip rings

40. Why should you use a high impedance multimeter when troubleshooting electronic equipment?

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

41. Air gap readings should be periodically taken for electrical generation equipment. The best tool to use to take these measurement is a

tapered, long blade gage

42. Which test on a transformer provides information about the regulation, efficiency and heating under load condition?

Back to back test

43. It is a type of electrical fault that happens when a phase conductor is completely or partially interrupted:

Open circuit fault

44. The windings of electric generators during short idle periods should be

kept warm by using strip or space heaters

45. The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the

main switchboard

46. A temperature instrumentationsystem for an engine room console consistes of a resistance temperature detector(RTD), a measuring bridge circuit, and a meter(or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?

The resistance bridge is said to be balanced when its output voltage is zero

47. In the event of a power failure during cargo loading operations, which of the following can stop the movement of an electric powered cargo winch?

A spring set brake

48. A device which can be used to check the calibration of a circuit breaker is a

portable low voltage high current testing unit

49. Before reassembling any machinery, what should you do?

clean any corroded surfaces and file all burrs smooth

50. Air gap readings should be periodically taken for electrical generation equipment. The best tool to use to take these measurements is a

tapered, long blade gage

51. A semiconductor that decreases in resistance with an increase in temperature is known as?.

thermistor

52. What should be done to protect the rotor of a motor disassembled for maintenance or overhaul?

it must be supported by two "V" notched wood blocks

53. What is a variable-resistance component used as a control device in electrical circuit?

Potentiometer

54. What kind of electrical cable that is widely used and is highly resistant to mechanical damage?

Aluminum cable covered with insulation.

55. When trouble shooting electronic equipment, what is the first step to be taken before testing the circuit voltage?

check the voltage supply from the power source

56. The purpose of a main switchboard circuit breaker's reverse-power trip is to

prevent alternator motorization

57. Temporary repairs to an open DC propulsion armature coil can be made by

disconnecting coil ends, insulating each, and short circuiting the two commutator bars

58. When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to

prevent excessive gassing and overheating

59. When shipboard electrical distribution circuits are connected in parallel, additional parallel circuits will cause the total circuit resistance to

decrease, causing an increase in the line current

60. What is a device that converts fluid powers into linear mechanical force and motion that consists of a movable piston, connecting rod, and plunger operating in a cylindrical cavity?

Cylinder

61. During maintenance of circuit breakers,

inspect for wear and misalignment of main contacts

MPLE

ユーザ名非公開 · 41問 · 13日前

MPLE