electrical

Alternator MCQ Questions and Answers Page - 5

1.

The alternators are operated in parallel because it

Answer/ Hint      

Answer : D

Explanation :

2.

Which one of the following is not necessary condition to be satisfied for synchronizing an incoming alternator to an already operating alternator?

Answer/ Hint      

Answer : C

Explanation :

3.

While synchronizing a 3-phase alternator to the bus-bar the paralleling switch should be closed

Answer/ Hint      

Answer : A

Explanation :

4.

The two bright and one dark lamp method is used for

Answer/ Hint      

Answer : B

Explanation :

5.

Desirable feature for successful parallel operation of two alternators is that both should have

Answer/ Hint      

Answer : C

Explanation :

6.

Two alternators are operating in parallel. For taking one of the alternators out from the system

Answer/ Hint      

Answer : A

Explanation :

7.

Synchronizing current means

Answer/ Hint      

Answer : C

Explanation :

8.

If the voltage of one of the two machines operating in parallel suddenly falls

Answer/ Hint      

Answer : C

Explanation :

9.

The electrical stiffness of a synchronous generator connected to a very large grid can be increased by

Answer/ Hint      

Answer : C

Explanation :

10.

Two alternators A and B are sharing an inductive load equally. If the excitation of alternator A is increased

Answer/ Hint      

Answer : B

Explanation :

11.

Two similar synchronous generators are working in parallel to supply a common load demand with identical excitations and steam supply to their prime movers. Now, if the steam supply to the prime mover of one of the generators is increased compared to the other, with field excitation kept unchanged, then

Answer/ Hint      

Answer : D

Explanation :

12.

When two alternators are operating in parallel, if the power input to one of the alternators is cut off, the alternator will

Answer/ Hint      

Answer : A

Explanation :

13.

An infinite bus bar has

Answer/ Hint      

Answer : D

Explanation :

14.

If the excitation of an alternator connected to an infinite bus bar is changed, keeping the power input to kits prime mover unchanged its ____will change.

Answer/ Hint      

Answer : D

Explanation :

15.

A stationary alternator should not be connected to the live bus bar because

Answer/ Hint      

Answer : D

Explanation :

16.

A 3-phase synchronous generator with constant power input is supplying electrical power to an infinite bus at a lagging power factor. If its excitation is reduced

Answer/ Hint      

Answer : A

Explanation :

17.

If the prime mover of an alternator supplying load to an infinite bus is suddenly shutdown, then it will

Answer/ Hint      

Answer : D

Explanation :

18.

Large-diameter salient-pole rotors have short axial length mainly because

Answer/ Hint      

Answer : C

Explanation :

19.

At leading power factor, the armature flux in an alternator

Answer/ Hint      

Answer : B

Explanation :

20.

Three-phase alternators are in variably star-connected because

Answer/ Hint      

Answer : A

Explanation :

21.

Which of the following conditions does not have to be met by alternators working in parallel?

Answer/ Hint      

Answer : D

Explanation :

22.

The fictions part of the synchronous reactance takes care of

Answer/ Hint      

Answer : B

Explanation :

23.

In an alternator the voltage of the field system is usually

Answer/ Hint      

Answer : C

Explanation :

24.

In an alternator, pitch factor is the ratio of the e.m.fs of

Answer/ Hint      

Answer : B

Explanation :

25.

In an alternator field the effect of cross magnetization is to make the output

Answer/ Hint      

Answer : A

Explanation :

26.

When two alternators are running in exact synchronism, the synchronizing power will be

Answer/ Hint      

Answer : B

Explanation :

27.

In an alternator if the armature reaction produces demagnetization of the main field, the power factor should be

Answer/ Hint      

Answer : B

Explanation :

28.

In an alternator, the armature reaction influences

Answer/ Hint      

Answer : A

Explanation :

29.

In an alternator, the frequency of voltage generated depends on

Answer/ Hint      

Answer : C

Explanation :

30.

In an alternator operating at lower voltage, for the same power rating will be

Answer/ Hint      

Answer : D

Explanation :

31.

When two alternators operating at lower voltage, for the same power rating, will be

Answer/ Hint      

Answer : C

Explanation :

32.

A lower voltage alternator, for the same power rating, will be

Answer/ Hint      

Answer : B

Explanation :

33.

Which of the following prime-mover is least efficient?

Answer/ Hint      

Answer : B

Explanation :

34.

One of the super thermal power stations is being located at

Answer/ Hint      

Answer : C

Explanation :

35.

If the voltage of one of the two machine running in synchronizing is suddenly increased

Answer/ Hint      

Answer : B

Explanation :

36.

In a larger generator protection provided against external fault is

Answer/ Hint      

Answer : D

Explanation :

37.

In large generators protection provided against external faults is

Answer/ Hint      

Answer : A

Explanation :

38.

………… plays an important role in over speed protection of a generator?

Answer/ Hint      

Answer : A

Explanation :

39.

Which of the following is the common synchronous speed in r.p.m between 50 Hz and be 60 Hz alternators?

Answer/ Hint      

Answer : C

Explanation :

40.

Salient pole type rotor as compared to cylindrical pole type are

Answer/ Hint      

Answer : D

Explanation :

41.

Which of the following relays come into operation in the event of the failure of the prime-mover connected to the generator?

Answer/ Hint      

Answer : B

Explanation :

42.

In order to reduce the harmonic in the e.m.f generated in an alternator

Answer/ Hint      

Answer : D

Explanation :

43.

The permissible duration for which a generator of rated frequency 50 Hz can run at 46 Hz is

Answer/ Hint      

Answer : B

Explanation :

44.

Due to which of the following reasons for aircraft alternators high frequency is used?

Answer/ Hint      

Answer : A

Explanation :

<< Previous
Alternator MCQ Questions and Answers Page - 5