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Electrical Engineering Objective Questions { Power System }

50. Buchholz relays are used for transformers of ratings above
A. 100 kV
B. 200 kV
C. 500 kV
D. 41000 kV

51. The power factor of the arc in a circuit breaker is
A. zero leading
B. zero lagging
C. unity
D. any value from zero to unity

52. A high speed circuit breaker can complete its operation in
A. 2 to 3 cycles
B. 3 to 8 cycles
C. 6 to 12 cycles
D. 10 to 20 cycles

53. Plug setting of a relay can be altered by varying
A. number of ampere-turns
B. air gap of magnetic path
C. adjustable back up stop
D. none of these

54. Various power system faults in increasing order of severity are
A. P.U. Xeq
B. Base MVA x P.U. Xeq Base MVA
C. (P.U. Xeq)2
D. none of these

55. Which of following are used to reduce short circuit fault currents
A. reactors
B. resistors
C. capacitors
D. parallel combination of all these

56. Pilot wire protection is basically used for the protection of
A. transmission lines
B. alternators
C. switch gears
D. transformers

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