Which of the following is the least expensive protection for overcurrent is low voltage system ?
A. Rewireable fuse
B. Isolator
C. Oil circuit breaker
D. Air break circuit breaker
E. None of the above
A. Rewireable fuse
B. Isolator
C. Oil circuit breaker
D. Air break circuit breaker
E. None of the above
A. 1 mega ohms
B. 10 mega ohms
C. 100 mega ohms
D. 500 mega ohms
Insulation resistance of high voltage circuit breakers is more than________________? Read More »
Switchgear and Protection A. motors
B. power outlet circuits
C. fluorescent lamps
D. light circuits
The delay fuses are used for the protection of ___________? Read More »
Switchgear and Protection A. 0.003 sec
B. 0.001 sec
C. 0.01 sec
D. 0.10 sec
E. none of the above
The time of closing the cycle, in modern circuit breakers is_____________? Read More »
Switchgear and Protection A. interception
B. interception and conduction
C. interception, conduction and dissipation
D. interception, conduction, dissipation and reflection
E. none of the above
A. power frequencies
B. higher frequencies entering generator or transformer units
C. either of the above
D. none of the above
Wave trap is used to trap waves of__________________? Read More »
Switchgear and Protection A. 33kVto66kV
B. HkVto33kV
C. 3.3kVandllkV
D. none of the above
Resistance grounding is used for voltage between_________________? Read More »
Switchgear and Protection A. 2
B. 4
C. 6
D. 10
The ground wire should not be smaller than No _________ copper Read More »
Switchgear and Protection A. arc suppressing blow out coils
B. wide separation of the opened contacts
C. high speed opening of contacts
D. all of the above
Interruption of large currents by relay requires______________? Read More »
Switchgear and Protection A. in phase with the arc current
B. lagging the arc current by 90″
C. leading the arc current by 90°
D. none of the above
The arc voltage produced in A.C. circuit breaker is always_____________? Read More »
Switchgear and Protection