Protective relays are devices that detect abnormal conditions in electrical circuits by measuring
A. current during abnormal condition
B. voltage during abnormal condition
C. constantly the electrical quantities which differ during normal and abnormal conditions
D. none of the above
Answer: Option C
This Question Belongs to Electrical Engineering >> Switchgear Protections
Magnetic circuit breaker has ______ trip action.
A. delayed
B. instantaneous
C. both of the above
D. none of the above
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
The arcing contacts in a circuit breaker are made of
A. copper tungsten alloy
B. porcelain
C. electrolytic copper
D. aluminium alloy
Air blast circuit breaker is used for
A. over currents
B. short duty
C. intermittant duty
D. repeated duty
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