electrical

Switchgear and Protection MCQ Objective Questions and Answers Page - 2

1.

Zero- sequence currents can flow from a line to transformer bank if the windings are in

Answer/ Hint      

Answer : A

Explanation :

2.

Fuses have got advantages of

Answer/ Hint      

Answer : D

Explanation :

3.

The primary function of a fuse is to

Answer/ Hint      

Answer : D

Explanation :

4.

The material used in liquid fuses is

Answer/ Hint      

Answer : C

Explanation :

5.

In comparison to rewirable fuses HRC fuses have the advantage(s) of

Answer/ Hint      

Answer : D

Explanation :

6.

In HRC fuse the time between cut-off and final current zero is called the

Answer/ Hint      

Answer : B

Explanation :

7.

If a combination of HRC fuse and a circuit breaker is employed, the circuit breaker operates for

Answer/ Hint      

Answer : B

Explanation :

8.

The least expensive protection for overcurrent in low-voltage system is

Answer/ Hint      

Answer : A

Explanation :

9.

A Circuit breaker normally operates

Answer/ Hint      

Answer : D

Explanation :

10.

When a fault occurs in a high voltage transmission line, first the

Answer/ Hint      

Answer : B

Explanation :

11.

The initiation of electric arc at the instant of contact separation is caused by

Answer/ Hint      

Answer : C

Explanation :

12.

Arcing voltage will be the least in case of

Answer/ Hint      

Answer : C

Explanation :

13.

The heat produced at the contact point owing to flow of electric current is least affected by

Answer/ Hint      

Answer : A

Explanation :

14.

Which of the following should have low value for the contacts and their material  ?

Answer/ Hint      

Answer : B

Explanation :

15.

In a CB Contact wipe is necessary

Answer/ Hint      

Answer : C

Explanation :

16.

Interrupting medium in a contactor may be

Answer/ Hint      

Answer : D

Explanation :

17.

The fluids used in circuit breakers should be of

Answer/ Hint      

Answer : D

Explanation :

18.

Sparking between contacts can be reduced by inserting

Answer/ Hint      

Answer : A

Explanation :

19.

For magnetic blow out of arc the magnetic field is produced

Answer/ Hint      

Answer : B

Explanation :

20.

In circuit breakers the contact space is ionized by

Answer/ Hint      

Answer : B

Explanation :

21.

In a circuit breaker, ionization is facilitated by

Answer/ Hint      

Answer : D

Explanation :

22.

The stability of arc in vacuum depends on

Answer/ Hint      

Answer : D

Explanation :

23.

The interrupting time of a circuit breaker is the period between the instant of

Answer/ Hint      

Answer : B

Explanation :

24.

For a high speed circuit breaker the total clearing time is around

Answer/ Hint      

Answer : C

Explanation :

25.

The resistance of an electric arc can be increased by

Answer/ Hint      

Answer : C

Explanation :

26.

The arc voltage in a circuit breaker is

Answer/ Hint      

Answer : A

Explanation :

27.

In a circuit breaker, the active recovery voltage depends upon

Answer/ Hint      

Answer : D

Explanation :

28.

In a circuit breaker the current that exists at the instant of contact separation is called the  _____________   current.

Answer/ Hint      

Answer : B

Explanation :

29.

The rate of rise of re-striking voltage (RRRV) depends upon

Answer/ Hint      

Answer : D

Explanation :

30.

The rate of rise of re-striking voltage (RRRV) is dependent upon

Answer/ Hint      

Answer : D

Explanation :

31.

It is difficult to interrupt a capacitive circuit because

Answer/ Hint      

Answer : B

Explanation :

32.

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

Answer/ Hint      

Answer : D

Explanation :

33.

The chances of arc interruption in subsequent current zeros

Answer/ Hint      

Answer : B

Explanation :

34.

In a minimum oil circuit breaker the oil is used

Answer/ Hint      

Answer : A

Explanation :

35.

The air-blast circuit breakers for  400 kV  system are designed to operate in

Answer/ Hint      

Answer : C

Explanation :

36.

The minimum oil circuit breaker has less volume of oil because

Answer/ Hint      

Answer : C

Explanation :

37.

Where voltages are high and current to be interrupted is low, the circuit breaker preferred is  _________  one.

Answer/ Hint      

Answer : B

Explanation :

38.

For rural electrification in a country like India with complex network, the circuit breaker preferred is  _________  One.

Answer/ Hint      

Answer : C

Explanation :

39.

The most suitable circuit breaker for short line fault without switching resistor is  ________  One.

Answer/ Hint      

Answer : C

Explanation :

40.

An isolator is meant for

Answer/ Hint      

Answer : C

Explanation :

41.

Relays can be designed to respond to changes in

Answer/ Hint      

Answer : D

Explanation :

42.

Overload relays are of ……. Type.

Answer/ Hint      

Answer : D

Explanation :

43.

Thermal overload relays are used to protect the mother against overcurrent due to

Answer/ Hint      

Answer : B

Explanation :

44.

Magnetic circuit breaker has   ___________   trip action

Answer/ Hint      

Answer : B

Explanation :

45.

D.C shunt relays are made of

Answer/ Hint      

Answer : C

Explanation :

46.

The relay operating speed depends upon

Answer/ Hint      

Answer : D

Explanation :

47.

On order that current should flow without causing excessive heating or voltage drop, the relay contacts should

Answer/ Hint      

Answer : D

Explanation :

48.

Circuit breakers usually operate under

Answer/ Hint      

Answer : A

Explanation :

49.

Circuit breakers are essentially

Answer/ Hint      

Answer : A

Explanation :

50.

The current zero interruption, in oil and air blast circuit breakers, is achieved by

Answer/ Hint      

Answer : C

Explanation :

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