891. Large internal faults are protected by_______________?
A. merz price percentage differential protection
B. mho and ohm relays
C. horn gaps and temperature relays
D. earth fault and positive sequence relays
892. The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage
A. recovery
B. surge
C. operating
D. arc
E. none of the above
893. In a circuit breaker the basic problem is to________________?
A. maintain the arc
B. extinguish the arc
C. transmit large power
D. emit the ionizing electrons
894. Magnetic circuit breaker has ___________ trip action
A. delayed
B. instantaneous
C. both of the above
D. none of the above
895. Fault diverters are basically____________?
A. fuses
B. relays
C. fast switches
D. circuit breakers
896. 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
897. The arcing contacts in a circuit breaker are made of______________?
A. copper tungsten alloy
B. porcelain
C. electrolytic copper
D. aluminium alloy
898. On which of the following routine tests are conducted ?
A. Oil circuit breakers
B. Air blast circuit breakers
C. Minimum oil circuit breakers
D. All of the above
899. Which of the following medium is employed for extinction of arc in air circuit breaker?
A. Water
B. Oil
C. Air
D. SF6
900. A thermal protection switch can protect against_____________?
A. short-circuit
B. temperature
C. overload
D. over voltage
NOTE
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