Air-Blust Circuit Breaker Objective Type Questions and answers

26.  The air blast circuit breakers for 400 KV system are designed to operate in

   A.0.1 sec

   B. 0.5 sec

   C. 50 msec

   D. 200 μsec

27.  Air used in air blast circuit breaker must

   A. Be ionised

   B. Be free from moisture

   C. Have least CO₂

   D. Have oil mist

28.  In air blast circuit breaker resistance switching is used to

   A. Read use the magnitude of the fault current

   B. Control the CB operating time

   C. Damp out the fast transient

   D. Change the fault current power factor

29.  While using air blast circuit breaker current, chopping is a phenomenon often observed when

   A. A long overhead line is switched off

   B. A bank of capacitors is switched off

   C. A transformer on no-load is switched off

   D. A heavy load is switched off

30.  The chances of arc interruption in subsequent current zeros

   A. Increase in case of ABCB but decrease in OCB

   B. Decrease in case of ABCB but increase in OCB

   C. Decrease in both cases

   D. Increase in both cases

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