electrical

Switchgear and Protection MCQ Objective Questions and Answers Page - 4

1.

A three-phase, 33 kV oil circuit breaker is rated  1200 A. 2000 MVA, 3 s. the symmetrical breaking current is

Answer/ Hint      

Answer : C

Explanation :

2.

A three-phase breaker is rated 2,000 MVA, 33 kV. Its making current will be

Answer/ Hint      

Answer : D

Explanation :

3.

Which of the following statements is not correct  ?

Answer/ Hint      

Answer : D

Explanation :

4.

The probable cause(s) for fall in insulation resistance between phase terminal and earthed frame could be

Answer/ Hint      

Answer : D

Explanation :

5.

The probable cause(s) for failure of a circuit breaker on electrical compound could be

Answer/ Hint      

Answer : D

Explanation :

6.

Routine tests are conducted on

Answer/ Hint      

Answer : D

Explanation :

7.

An isolator is installed

Answer/ Hint      

Answer : D

Explanation :

8.

Current rating is not necessary in case of

Answer/ Hint      

Answer : A

Explanation :

9.

The protective relay is provided to

Answer/ Hint      

Answer : B

Explanation :

10.

Plug setting of an electromagnetic relay can be altered by varying

Answer/ Hint      

Answer : A

Explanation :

11.

The torque produced in shaded pole structure induction type relay is

Answer/ Hint      

Answer : A

Explanation :

12.

The most efficient torque-producing actuating structure for induction-type relays is

Answer/ Hint      

Answer : C

Explanation :

13.

A bimetal strip, in a thermal relay, consists of two metal strips of different

Answer/ Hint      

Answer : C

Explanation :

14.

Thermal relays are used for protection of motors against over-current owing to

Answer/ Hint      

Answer : B

Explanation :

15.

Buchholz relay is

Answer/ Hint      

Answer : C

Explanation :

16.

Buchholz relay are used on

Answer/ Hint      

Answer : D

Explanation :

17.

The Buchholz relay protects a transformer from

Answer/ Hint      

Answer : A

Explanation :

18.

Which of the following relays  is/are  overload relays  ?

Answer/ Hint      

Answer : D

Explanation :

19.

In an overcurrent protection the setting of the earth fault relay is

Answer/ Hint      

Answer : C

Explanation :

20.

Inverse time-current relays are used for the protection of

Answer/ Hint      

Answer : D

Explanation :

21.

IDMT relays are used to protect the power transformers against

Answer/ Hint      

Answer : D

Explanation :

22.

In an inverse definite minimum time, electromagnetic type overcurrent relay, the minimum time feature is achieved because of

Answer/ Hint      

Answer : A

Explanation :

23.

Earth fault relays are

Answer/ Hint      

Answer : A

Explanation :

24.

The domains of power system where directional overcurrent relay is indispensable are

Answer/ Hint      

Answer : C

Explanation :

25.

Directional overcurrent relays have two exciting coils connected across

Answer/ Hint      

Answer : C

Explanation :

26.

In distance protection, the relay measures

Answer/ Hint      

Answer : B

Explanation :

27.

If the fault occurs near the relay, the  V/I ratio will be

Answer/ Hint      

Answer : A

Explanation :

28.

Impedance relay may use

Answer/ Hint      

Answer : D

Explanation :

29.

Impedance relay can be used for

Answer/ Hint      

Answer : A

Explanation :

30.

An impedance relay is a

Answer/ Hint      

Answer : A

Explanation :

31.

Threshold characteristics of a plain impedance relay in a complex Z plane is a

Answer/ Hint      

Answer : B

Explanation :

32.

On transient fault OC and impedance relay.

Answer/ Hint      

Answer : A

Explanation :

33.

The structure used in reactance relays is

Answer/ Hint      

Answer : D

Explanation :

34.

A reactance relay is

Answer/ Hint      

Answer : C

Explanation :

35.

The operating characteristics of a reactance relay in the complex impedance plane is a

Answer/ Hint      

Answer : D

Explanation :

36.

Reactance relay is normally used for protection against

Answer/ Hint      

Answer : A

Explanation :

37.

Admittance relay is

Answer/ Hint      

Answer : C

Explanation :

38.

A mho relay is a

Answer/ Hint      

Answer : A

Explanation :

39.

A Mho relay is a

Answer/ Hint      

Answer : A

Explanation :

40.

For ground fault we preffer  :

Answer/ Hint      

Answer : C

Explanation :

41.

An over current relay is said to over reach when it operates at a current

Answer/ Hint      

Answer : C

Explanation :

42.

A distance relay with inherent directional property is known as

Answer/ Hint      

Answer : B

Explanation :

43.

A distance relay is said to be inherently Directional if its characteristics on R-X diagram

Answer/ Hint      

Answer : B

Explanation :

44.

For the protection of lines against faults involving variable fault resistance, the preferred relaying scheme is a

Answer/ Hint      

Answer : D

Explanation :

45.

The relay used for phase fault protection of short transmission lines is

Answer/ Hint      

Answer : A

Explanation :

46.

Mho relay is usually employed for the protection of

Answer/ Hint      

Answer : C

Explanation :

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