electrical

Switchgear and Protection MCQ Objective Questions and Answers Page - 5

1.

Where severe synchronising swing occur, the relay employed is

Answer/ Hint      

Answer : B

Explanation :

2.

Which of the following relays has inherent directional characteristic  ?

Answer/ Hint      

Answer : A

Explanation :

3.

A differential relay responds to

Answer/ Hint      

Answer : B

Explanation :

4.

Difference relays are used for protection of equipment against

Answer/ Hint      

Answer : A

Explanation :

5.

Undervoltage relays are mainly used for

Answer/ Hint      

Answer : D

Explanation :

6.

In a biased differential relay the bias is defined as a ratio of

Answer/ Hint      

Answer : A

Explanation :

7.

Differential relays are used for protection of

Answer/ Hint      

Answer : D

Explanation :

8.

Both voltage and current signals are required for

Answer/ Hint      

Answer : C

Explanation :

9.

The relay used for feeder protection is

Answer/ Hint      

Answer : B

Explanation :

10.

In the case of transmission line protection, overcurrent relay is used

Answer/ Hint      

Answer : C

Explanation :

11.

Phase relays are used to provide protection against

Answer/ Hint      

Answer : C

Explanation :

12.

In a 3-phase circuit, residual current means the flow of  __________ current.

Answer/ Hint      

Answer : B

Explanation :

13.

Zero- sequence current is used for relaying purposes only in the case of

Answer/ Hint      

Answer : C

Explanation :

14.

Over conventional electromechanical relays, the transistor relays have the advantages of

Answer/ Hint      

Answer : D

Explanation :

15.

Over conventional electromechanical relays, the transistor relays have the limitations of

Answer/ Hint      

Answer : D

Explanation :

16.

In a static overcurrent relay, inverse time characteristics are obtained by

Answer/ Hint      

Answer : B

Explanation :

17.

Two-input phase comparator in a static relay is made up of a

Answer/ Hint      

Answer : C

Explanation :

18.

The phase comparators in case of static relays and electromechanical relay normally are

Answer/ Hint      

Answer : A

Explanation :

19.

Merz-Price protection is employed for protection of

Answer/ Hint      

Answer : D

Explanation :

20.

Negative-sequence voltages in the stator induces.

Answer/ Hint      

Answer : A

Explanation :

21.

The short-circuit current of an alternator, in case of line to line fault, depends on its

Answer/ Hint      

Answer : C

Explanation :

22.

We do not require any protection against prime mover failure in case of

Answer/ Hint      

Answer : A

Explanation :

23.

For the protection of stator winding of an alternator against internal fault involving ground, the relay used is a

Answer/ Hint      

Answer : A

Explanation :

24.

The bias factor S in unit protection synchronous generators

Answer/ Hint      

Answer : A

Explanation :

25.

Field failure in an alternator occurs due to

Answer/ Hint      

Answer : D

Explanation :

26.

A soon as a fault develops in a generator stator, it is essential to suppress field excitation, otherwise

Answer/ Hint      

Answer : C

Explanation :

27.

If there is an open circuit in the field circuit of a generator

Answer/ Hint      

Answer : D

Explanation :

28.

The earth fault in stator causes

Answer/ Hint      

Answer : D

Explanation :

29.

Failure of insulation on stator winding of generator results in

Answer/ Hint      

Answer : D

Explanation :

30.

The magnitude of earth-fault current for a given fault position within a winding depends upon

Answer/ Hint      

Answer : D

Explanation :

31.

For the protection of a large squirrel-cage induction motor against single phase normally

Answer/ Hint      

Answer : D

Explanation :

32.

The main function of undervoltage protective device generally employed with a motor starter is to

Answer/ Hint      

Answer : A

Explanation :

33.

While adding extra stop buttons to an existing control system they must be in

Answer/ Hint      

Answer : B

Explanation :

34.

The types of faults that occur in electric motors are

Answer/ Hint      

Answer : D

Explanation :

35.

Negative-sequence currents flow in the stator windings of an ac motor due to

Answer/ Hint      

Answer : D

Explanation :

36.

A negative sequence relay is commonly used to product

Answer/ Hint      

Answer : A

Explanation :

37.

Earth fault protection for an electric motor is provided by means of

Answer/ Hint      

Answer : D

Explanation :

38.

Any winding of a power transformer develops short-circuit owing to

Answer/ Hint      

Answer : B

Explanation :

39.

Which of the following relays has the capacity of anticipating the possible major fault in a transformer ?

Answer/ Hint      

Answer : C

Explanation :

40.

Which relay is used to detect and protect internal faults of a transformer  ?

Answer/ Hint      

Answer : A

Explanation :

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