electrical

Alternator MCQ Questions and Answers Page - 4

1.

A leading pf load on an alternator implies that its voltage regulation shall be

Answer/ Hint      

Answer : D

Explanation :

2.

The effect of leading power factor on the voltage regulation of an alternator is

Answer/ Hint      

Answer : B

Explanation :

3.

The leakage reactance of a three-phase alternator is determined by performing

Answer/ Hint      

Answer : A

Explanation :

4.

The synchronous impedance method of finding the voltage regulation of a cylindrical rotor alternator is generally considered as

Answer/ Hint      

Answer : A

Explanation :

5.

The regulation obtained by synchronous impedance method is always higher than actual value because

Answer/ Hint      

Answer : C

Explanation :

6.

The short circuit characteristics of an alternator is

Answer/ Hint      

Answer : A

Explanation :

7.

Under short –circuit conditions, the power factor of an alternator is

Answer/ Hint      

Answer : B

Explanation :

8.

The zero-power factor characteristic for the Potier diagram can be obtained by loading the alternator using

Answer/ Hint      

Answer : B

Explanation :

9.

Modern alternators are designed to have poor regulation as it

Answer/ Hint      

Answer : B

Explanation :

10.

Armature reaction mmf and leakage reactance of a synchronous machine are determined by

Answer/ Hint      

Answer : B

Explanation :

11.

Which one of the following methods would give higher than actual value of regulation of an alternator?

Answer/ Hint      

Answer : C

Explanation :

12.

Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator?

Answer/ Hint      

Answer : C

Explanation :

13.

Slip test is performed to determined

Answer/ Hint      

Answer : B

Explanation :

14.

For maximum current during slip test on a synchronous machine the armature mmf align along

Answer/ Hint      

Answer : B

Explanation :

15.

In which one of the following is reluctance power developed?

Answer/ Hint      

Answer : A

Explanation :

16.

Which is the value of load angle when the power output of a salient pole synchronous generator is maximum?

Answer/ Hint      

Answer : D

Explanation :

17.

An alternator with higher value of SCR has

Answer/ Hint      

Answer : B

Explanation :

18.

If the excitation of a 3-phase alternator operating on infinite bus bars is changed, which one of the following shall alter?

Answer/ Hint      

Answer : B

Explanation :

19.

A 3-phase synchronous generator with constant steam input supplied power to an infinite bus at a lagging power factor. If the excitation is increased

Answer/ Hint      

Answer : A

Explanation :

20.

A turbo alternator set feeds power to a 3-phase constant voltage constant frequency bus. If the steam supply to the set is cut off, then the set will

Answer/ Hint      

Answer : A

Explanation :

21.

The mmf produced by single phase winding is

Answer/ Hint      

Answer : B

Explanation :

22.

A polyphase field is

Answer/ Hint      

Answer : C

Explanation :

23.

A synchronous generator has its field winding on the rotor and armature winding on the stator. When running under steady state conditions its air gap field is

Answer/ Hint      

Answer : D

Explanation :

24.

The load between two steam-driven alternators operating in parallel may be adjusted by varying

Answer/ Hint      

Answer : A

Explanation :

25.

Overheating of generator’s winding

Answer/ Hint      

Answer : A

Explanation :

26.

The maximum current that can be supplied by an alternator depends on

Answer/ Hint      

Answer : D

Explanation :

27.

The regulation of an alternator is likely to be negative in case of

Answer/ Hint      

Answer : B

Explanation :

28.

The regulation of an alternators is

Answer/ Hint      

Answer : A

Explanation :

29.

An alternator is said to be over excited when it is operating at

Answer/ Hint      

Answer : B

Explanation :

30.

An alternator driven by francies hydraulic turbine is a ……………. Alternators

Answer/ Hint      

Answer : D

Explanation :

31.

If two alternators are running in proper synchronous are running in proper synchronism and the voltage of one machine is suddenly increased

Answer/ Hint      

Answer : C

Explanation :

32.

The power factor of an alternator is determined by its

Answer/ Hint      

Answer : D

Explanation :

33.

Two alternators are to be put in parallel. Which of the following factor should be identical for both

Answer/ Hint      

Answer : D

Explanation :

34.

If the steam supply of an alternator running in parallel with another identical alternator is increased keeping its excitation constant then.

Answer/ Hint      

Answer : A

Explanation :

35.

An exciter for a generator is a

Answer/ Hint      

Answer : C

Explanation :

36.

Two alternators ‘1’ and “2” are sharing an inductive load equally. If the excitation of alternator ‘1’ is increased

Answer/ Hint      

Answer : A

Explanation :

37.

Which of the following coils in an alternator will have e.m.f closer to sine waveform?

Answer/ Hint      

Answer : B

Explanation :

38.

The distribution factor, in alternators is defined as the ratio e.m.f of

Answer/ Hint      

Answer : C

Explanation :

39.

As load power factor of an alternator becomes more leading, the value of generated voltage required to give rated terminal voltage

Answer/ Hint      

Answer : A

Explanation :

40.

In an alternator, the flux created by the armature m.m.f subtracts directly from the main flux for the following conditions of load

Answer/ Hint      

Answer : C

Explanation :

41.

Synchronous impedance method of finding voltage regulation of an alternators is called pessimistic method because

Answer/ Hint      

Answer : B

Explanation :

42.

In a synchronous machine, if the field flux axis is ahead of the armature field axis, in the direction of rotation the machine is working as

Answer/ Hint      

Answer : A

Explanation :

43.

In a synchronous machine, if the field flux axis is ahead of the armature field axis, in the direction of rotation, the machine is working as

Answer/ Hint      

Answer : A

Explanation :

44.

The advantage of salient pole in an alternator is

Answer/ Hint      

Answer : D

Explanation :

45.

For parallel operation of the two alternator, desirable feature is that both should have

Answer/ Hint      

Answer : D

Explanation :

46.

If two alternators are running in parallel and excitation of one of the alternators is increased, then

Answer/ Hint      

Answer : B

Explanation :

47.

When an alternator is supplying unity power factor load, the armature reaction will produce

Answer/ Hint      

Answer : A

Explanation :

48.

If the driving force of both the alternators running in parallel is changed, this will result in change in

Answer/ Hint      

Answer : B

Explanation :

49.

In an alternator, when the load power factor is unity

Answer/ Hint      

Answer : B

Explanation :

50.

The potier’s triangle separates the

Answer/ Hint      

Answer : C

Explanation :

51.

In an alternator zero power factor method is used to find the

Answer/ Hint      

Answer : D

Explanation :

52.

If the driving power from the prime from the prime mover driving an alternator is lost but the alternator remains connected to the supply network and field supply network and field supply is on then the alternator will

Answer/ Hint      

Answer : B

Explanation :

53.

In turbo-alternators, smooth cylindrical type rotor used have long axial length because

Answer/ Hint      

Answer : D

Explanation :

54.

Which of the following methods used for synchronizing of 3-phsae synchronous generator is considered best one?

Answer/ Hint      

Answer : C

Explanation :

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