electrical

Switchgear and Protection MCQ Objective Questions and Answers Page - 7

1.

The protection against direct lightning strokes and high voltage steep waves is provided by

Answer/ Hint      

Answer : C

Explanation :

2.

Which of the following factors should be considered the design of a transmission line against lightning with ground wire  ?

Answer/ Hint      

Answer : D

Explanation :

3.

For protection of rotating machines against lightning surges  ___________  is used

Answer/ Hint      

Answer : C

Explanation :

4.

Lighting arresters are used in power system to protect electrical equipments against

Answer/ Hint      

Answer : C

Explanation :

5.

Impulse ratios of insulators and lightning arresters should be

Answer/ Hint      

Answer : B

Explanation :

6.

Which of the following is the protective device against lightning over-voltages  ?

Answer/ Hint      

Answer : D

Explanation :

7.

Overhead ground wires are used to protect a transmission line against

Answer/ Hint      

Answer : C

Explanation :

8.

An overhead transmission line is provided with earth wire for protection against

Answer/ Hint      

Answer : B

Explanation :

9.

In a thyrite lightning arrester the resistance

Answer/ Hint      

Answer : D

Explanation :

10.

A lightning arrester provides

Answer/ Hint      

Answer : A

Explanation :

11.

Surge absorbers are used for protection against

Answer/ Hint      

Answer : C

Explanation :

12.

Surge modifiers are employed for

Answer/ Hint      

Answer : A

Explanation :

13.

A thyrite type lightning arrester

Answer/ Hint      

Answer : C

Explanation :

14.

A lightning arrester connected between the line earth in a power system

Answer/ Hint      

Answer : A

Explanation :

15.

Which of the following is a non-linear diverter  ?

Answer/ Hint      

Answer : B

Explanation :

16.

A valve type lightning arrestor in a substation should be placed

Answer/ Hint      

Answer : B

Explanation :

17.

Surge absorber  ____________  the energy of travelling waves

Answer/ Hint      

Answer : D

Explanation :

18.

Coupling factor of a ground wire can be increased by

Answer/ Hint      

Answer : D

Explanation :

19.

In the presence of corona, electrostatic coupling  ____________  and electromagnetic coupling  ___________

Answer/ Hint      

Answer : C

Explanation :

20.

When a transmission line is energized,  ___________  propagate on it

Answer/ Hint      

Answer : C

Explanation :

21.

When a wave propagate on a transmission line, it suffers reflection several times at

Answer/ Hint      

Answer : C

Explanation :

22.

Travelling voltage wave and current wave have the same waveforms and travel together along the transmission line at a velocity

Answer/ Hint      

Answer : C

Explanation :

23.

For a transmission line the standing wave ratio is the ratio of

Answer/ Hint      

Answer : C

Explanation :

24.

The steepness of the wave-front can be reduced by connecting

Answer/ Hint      

Answer : C

Explanation :

25.

If the load impedance is  100 ohm  and input impedance is  25 ohm,  then the characteristic impedance of the transmission line is

Answer/ Hint      

Answer : C

Explanation :

26.

The insulation strength of an  EHV  transmission line is mainly governed by

Answer/ Hint      

Answer : B

Explanation :

27.

The insulation coordination for  UHV  lines (above  500 kV) is dine based on

Answer/ Hint      

Answer : C

Explanation :

28.

In comparison to line insulation, the insulation level of the station equipment is

Answer/ Hint      

Answer : D

Explanation :

29.

The size of the earth wire is determined on the basis of

Answer/ Hint      

Answer : B

Explanation :

30.

Neutral earthing is provided for

Answer/ Hint      

Answer : D

Explanation :

31.

Isolated neutral system has the disadvantage(s) of

Answer/ Hint      

Answer : D

Explanation :

32.

Isolated neutral transmission system is not recommended as the

Answer/ Hint      

Answer : D

Explanation :

33.

Neutral earthing has the advantage(s) of

Answer/ Hint      

Answer : D

Explanation :

34.

The advantage of neutral earthing is

Answer/ Hint      

Answer : C

Explanation :

35.

Resistance earthing is employed for voltages between

Answer/ Hint      

Answer : A

Explanation :

36.

Earthing of transformer neutral through reactance will improve its

Answer/ Hint      

Answer : A

Explanation :

37.

Which of the following neutral system will require the lightning arrester of least voltage rating  ?

Answer/ Hint      

Answer : B

Explanation :

38.

Petersan coil is used for

Answer/ Hint      

Answer : A

Explanation :

39.

Which one of the following grounding methods is used to reduce the tower footing resistance where earth resistance is low  ?

Answer/ Hint      

Answer : A

Explanation :

40.

Tower footing resistance of a transmission tower should be

Answer/ Hint      

Answer : B

Explanation :

41.

Bus coupler is very essential in   _____________   arrangement

Answer/ Hint      

Answer : C

Explanation :

42.

For cost and safety, the outdoor substations are installed for voltages above

Answer/ Hint      

Answer : B

Explanation :

43.

The short circuit in any winding of the transformer is the result of

Answer/ Hint      

Answer : D

Explanation :

44.

_____________   relays are used for phase faults on long line.

Answer/ Hint      

Answer : A

Explanation :

45.

For which of the following protection from negative sequence currents is provided?

Answer/ Hint      

Answer : A

Explanation :

46.

_____________ relay is preferred for phase fault on short transmission line.

Answer/ Hint      

Answer : B

Explanation :

47.

Distance relays are generally

Answer/ Hint      

Answer : D

Explanation :

48.

For which of the following ratings of the transformer differential protection is recommended?

Answer/ Hint      

Answer : B

Explanation :

49.

A   ______________   is used to measure the stator winding temperature of the generator.

Answer/ Hint      

Answer : C

Explanation :

50.

The under-voltage relay can be used for

Answer/ Hint      

Answer : D

Explanation :

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