MCQs Electrical Engineering
1. Which of the following is not a part of the circuit breaker ?
(1) Operating mechanism
(2) Conservator
(3) Explosion pot
(4) Fixed and moving contacts
Ans (2)
2. Breaking capacity of a circuit breaker is usually expressed in :
(1 ) Volts
(2) Amperes
(3) MVA
(4) MW
Ans (3)
3. The recovery voltage that appears across the circuit breaker contacts will be maximum for power factor of
(1)zero
(2) 0.5
(3) 0.707
(4) unity
Ans (1)
4. An air blast circuit breaker is usually employed for :
(1) Instantaneous voltage
(2) intermittent duty
(3) repeated duty
(4) short duty
Ans (3)
5. The making current of 3-phase breaker with rating 2000 MVA, 33 kV will be -
(1) 35 A
(2) 50A
(3) 70 kA
(4) 89 A.
Ans (4)
6. A circuit breaker is rated as follows : 1500 A, 33KV, 3 sec, 3- phase oil circuit breaker. Determine the making current ?
(1) 110 A
(2 ) 35 A
(3) 1.5 A
(4) 89 A
Ans (4)
7. If in a circuit breaker, the length of an are increases, then the are resistance-
(1) increases
(2) remains unchanged
(3) become zero
(4) decreases
Ans (1)
8. A 3-phase circuit breaker is rated at 1250A, 2000MVA, 33KV, 4s. Its making current capacity will be
(1) 35 A
(2) 89 A
(3) 79 A
(4) 69 A
Ans (2)
9. The following statements associated with Buchholtz relays is not true :
(1) It is a gas actuated device
(2) It is a current operative device
(3) It is placed between the transformer tank and the conservator
(4) It cause alarm for minor fault and tripping forf major fault
Ans (2)
10. A relay performs the function of -
(1) fault isolation
(2) fault detection
(3) fault prevention
(4) All the above
Ans (2)
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