switchgear and protection MCQs – Page 3

Practise focused switchgear and protection questions with marked answers for exam preparation and subject revision.

switchgear and protection Mcqs
41. Fault diverters are basically____________?
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A. circuit breakers

B. fuses

C. relays

D. fast switches
42. When a wave propagates on a transmission line, it suffers reflection several times at_____________?
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A. tapping

B. sending end

C. load end

D. sending and other end

E. all of the above

43. Overload relays are of_______________type
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A. electromagnetic

B. all above

C. solid state

D. induction

E. thermal

44. The current zero interruption, in oil and air blast circuit breakers, is achieved by_______________?
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A. lengthening of the gap

B. cooling and blast effect

C. both A. and B

D. deionizing the oil with forced air

E. none of the above

45. SF6 gas______________?
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A. none of the above

B. is lighter than air

C. is yellow in colour

D. is nontoxic

E. has pungent small

46. H.R.C. fuse, as compared to a rewirable fuse, has_________________?
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A. high speed of operation

B. all of the above

C. no ageing effect

D. high rupturing capacity

47. Directional relays are based on flow of____________?
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A. voltage wave

B. all of the above

C. current

D. power
48. A switchgear is device used for_____________?
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A. switching an electrical circuit 111.

B. interrupting an electrical circuit

C. switching and controlling an electrical circuit

D. switching, controlling and protecting the electrical circuit and equipment
49. The relay operating speed depends upon_________________?
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A. all of the above

B. armature core air gap

C. the spring tension

D. the rate of flux built up

50. Protective relays are devices that detect abnormal conditions in electrical circuits by measuring_____________?
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A. none of the above

B. voltage during abnormal condition

C. constantly the electrical quantities which differ during normal and abnormal conditions

D. current during abnormal condition

51. Series reactors should have________________?
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A. high impedance

B. low resistance

C. low impedance

D. high resistance

52. The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to______________?
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A. none of the above

B. lubricate the contacts

C. extinguish the arc

D. insulate the contacts from switch body

E. all of the above

53. A fuse is connected_______________?
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A. in parallel with circuit

B. none of the above

C. either in series or in parallel with circuit

D. in series with circuit
54. A short-circuit is identified by_____________?
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A. heavy current flow

B. no current flow

C. voltage drop

D. voltage rise

55. Thermal circuit breaker has____________?
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A. delayed trip action

B. instantaneous trip action

C. both of the above

D. none of the above

56. H.R.C. fuses provide best protection against________________?
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A. overload

B. reverse current

C. short-circuits

D. open-circuits

57. Bus coupler is very essential in arrangement______________?
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A. main and transfer bus

B. all of the above

C. double bus, double breaker

D. single bus

58. Thermal overload relays are used to protect the motor against over current due to____________?
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A. grounds

B. heavy loads

C. all of the above

D. short-circuits

59. For cost and safety, the outdoor substations are installed for voltages above_________________?
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A. 33 kV

B. 110kV

C. 60kV

D. 11 kV

60. The steady state stability of the power system can be increased by_____________?
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A. none of the above

B. connecting lines in series

C. connecting lines in parallel

D. using machines of high impedance

E. reducing the excitation of machines