electrical

Switchgear and Protection MCQ Objective Questions and Answers Page - 3

1.

In circuit breakers, oil, as quenching medium, has the disadvantage(s) of

Answer/ Hint      

Answer : D

Explanation :

2.

Main purpose of oil in OCB is to

Answer/ Hint      

Answer : C

Explanation :

3.

Air used in air blast circuit breaker must

Answer/ Hint      

Answer : B

Explanation :

4.

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

Answer/ Hint      

Answer : C

Explanation :

5.

In air-blast circuit breaker resistance switching is used to

Answer/ Hint      

Answer : C

Explanation :

6.

SF6  gas has excellent heat transfer properties because of its

Answer/ Hint      

Answer : D

Explanation :

7.

SF6  circuit breakers have the advantages of

Answer/ Hint      

Answer : D

Explanation :

8.

SF6  circuit breakers have the drawback(s) of

Answer/ Hint      

Answer : D

Explanation :

9.

Which of the following statements is not correct  ?

Answer/ Hint      

Answer : C

Explanation :

10.

The single most important property that makes  SF6 a very efficient medium for circuit breaking is

Answer/ Hint      

Answer : D

Explanation :

11.

During arc extinction  SF6  gas gets

Answer/ Hint      

Answer : A

Explanation :

12.

SF6  gas is transported in

Answer/ Hint      

Answer : C

Explanation :

13.

The current chopping tendency is minimised by using   SF6  gas at relatively

Answer/ Hint      

Answer : B

Explanation :

14.

To limit current chopping in vacuum circuit breakers, the contact material employed should have the properties of

Answer/ Hint      

Answer : A

Explanation :

15.

A thermal protection switch provides protection against

Answer/ Hint      

Answer : A

Explanation :

16.

For remote operation, the circuit breaker must be equipped with

Answer/ Hint      

Answer : B

Explanation :

17.

Which of the following circuit breakers is generally used in railway electrification  ?

Answer/ Hint      

Answer : A

Explanation :

18.

What is the preferred type of  CB  to be installed in extra high voltage ac system  ?

Answer/ Hint      

Answer : D

Explanation :

19.

Keeping in view the cost and overall effectiveness, the following circuit breaker is beat suited for capacitor bank switching

Answer/ Hint      

Answer : A

Explanation :

20.

Which of the following circuit breakers has the lowest voltage range  ?

Answer/ Hint      

Answer : D

Explanation :

21.

Which of the following circuit breakers produce the least arc energy  ?

Answer/ Hint      

Answer : C

Explanation :

22.

Which of the following circuit breakers has high reliability and negligible maintenance  ?

Answer/ Hint      

Answer : B

Explanation :

23.

Which of the following circuit breakers take minimum time in installation  ?

Answer/ Hint      

Answer : D

Explanation :

24.

The rating of a circuit breaker is usually determined on the basis of  ___________  fault.

Answer/ Hint      

Answer : A

Explanation :

25.

The transient phenomenon lasts in a power system for a period ranging from

Answer/ Hint      

Answer : A

Explanation :

26.

Circuit breakers usually operate under

Answer/ Hint      

Answer : B

Explanation :

27.

The re-striking voltage is measured in

Answer/ Hint      

Answer : B

Explanation :

28.

The making and breaking currents of  3-phase ac circuit breakers in power system are respectively in what form  ?

Answer/ Hint      

Answer : B

Explanation :

29.

Rated breaking  capacity (MVA)  of a circuit breaker is equal to

Answer/ Hint      

Answer : B

Explanation :

30.

The making to breaking current ratio  for an  EHV  circuit breaker is

Answer/ Hint      

Answer : A

Explanation :

31.

The making capacity of a circuit breaker is

Answer/ Hint      

Answer : B

Explanation :

32.

Isolators used in transmission lines are capable of breaking  :

Answer/ Hint      

Answer : C

Explanation :

33.

The oil switches may be

Answer/ Hint      

Answer : D

Explanation :

34.

Which of the following sequence of operation is correct for operation of circuit breaker, isolator and earthing switch while opening a circuit  ?

Answer/ Hint      

Answer : A

Explanation :

35.

Which of the following sequence of operation is correct for operation of circuit breaker, isolator and earthing switch while closing a circuit  ?

Answer/ Hint      

Answer : B

Explanation :

36.

Purpose of backup protection is

Answer/ Hint      

Answer : D

Explanation :

37.

Protective relays are the devices that detect abnormal conditions in electrical circuit by measuring

Answer/ Hint      

Answer : C

Explanation :

38.

The actuating quantity for the relays may be

Answer/ Hint      

Answer : D

Explanation :

39.

Protective relays can be designed to respond to

Answer/ Hint      

Answer : D

Explanation :

40.

The operating speed of a relay depends upon the

Answer/ Hint      

Answer : D

Explanation :

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