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.Management Sciences
Category: Switchgear and Protection
Air blast circuit breakers for 400 kV power system are designed to operate in_______________?
0
A. 100 microsecond
B. 50 millisecond
C. 0.5 sec
D. 0.1 sec
Circuit breakers usually operate under______________?
A. transient state of short-circuit current
B. sub-transient state of short-circuit current
C. steady state of short-circuit current
D. after D.C. component has ceased
Magnetic circuit breaker has ___________ trip action
A. delayed
B. instantaneous
C. both of the above
D. none of the above
Interruption of large currents by relay requires______________?
A. arc suppressing blow out coils
B. wide separation of the opened contacts
C. high speed opening of contacts
D. all of the above
Arc in a circuit behaves as_______________?
A. a capackive reactance
B. an inductive reactance
C. a resistance increasing with voltage rise across the arc
D. a resistance decreasing with voltage rise across the arc
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