electrical

DC Generator MCQ Objective Questions and Answers Page - 2

1.

 In  a dc motor the windage loss is proportional to

Answer/ Hint      

Answer : D

Explanation :

2.

Which of the following are the variable losses in a rotating machine ?

Answer/ Hint      

Answer : D

Explanation :

3.

Stray losses are sum of

Answer/ Hint      

Answer : A

Explanation :

4.

 Generally the no – load losses of an electrical machine is represented in its equivalent circuit by

Answer/ Hint      

Answer : C

Explanation :

5.

Neglecting all losses, how is the developed torque (T) of a dc separately excited motor, operating under constant terminal voltage, related  to its output power (P)

Answer/ Hint      

Answer : B

Explanation :

6.

The principale of dynamically induced emf is utilized in

Answer/ Hint      

Answer : C

Explanation :

7.

In a dc machine

Answer/ Hint      

Answer : A

Explanation :

8.

Which of the following is not a part of dc machine  ?

Answer/ Hint      

Answer : D

Explanation :

9.

The field coils of a dc generator are usually made of

Answer/ Hint      

Answer : B

Explanation :

10.

Laminated yoke in dc motor can reduce

Answer/ Hint      

Answer : B

Explanation :

11.

The field coils of a dynamo have an inductance of 8 H and have a resistance of 60 Ω and are connected to 120 V dc source . The steady state current in the filed coil is

Answer/ Hint      

Answer : B

Explanation :

12.

A 4-pole lap wound dc generator has a developed power of P watts and voltage of E volts. The adjacent brushes of the machine are removed as they are worn out. If the machine  operates with the

Answer/ Hint      

Answer : D

Explanation :

13.

The armature resistance of a 6 pole lap wound dc machine is 0.05 Ω. If the armature is rewound as a wave winding, what is the armature resistance ?

Answer/ Hint      

Answer : A

Explanation :

14.

In dc machines, the air gap flux distribution in space at no load is

Answer/ Hint      

Answer : C

Explanation :

15.

The armature MMF waveform of a dc machine is

Answer/ Hint      

Answer : C

Explanation :

16.

The armature mmf of a dc machine has

Answer/ Hint      

Answer : D

Explanation :

17.

In a dc machine , the actual flux distribution depends upon

Answer/ Hint      

Answer : D

Explanation :

18.

In a dc machine, the spae waveform of the air gap flux distribution affects

Answer/ Hint      

Answer : D

Explanation :

19.

In a dc machine the armature mmf is

Answer/ Hint      

Answer : A

Explanation :

20.

Armature reaction in dc shunt generator , running at full load with the brushed not shifted form the geometrical neutral place and saturation neglected is

Answer/ Hint      

Answer : B

Explanation :

21.

In a dc machine without any brush shift, the shift of the magnetic neutral axis owing to armature reaction is

Answer/ Hint      

Answer : C

Explanation :

22.

 In a dc machine on no load the magnetic neutral axis

Answer/ Hint      

Answer : C

Explanation :

23.

Due to magnetic saturation, the flux per pole I a dc machine without brush shift

Answer/ Hint      

Answer : B

Explanation :

24.

In a dc machine the number of mechanical and electrical degree will be same when the number of poles on the machine is

Answer/ Hint      

Answer : B

Explanation :

25.

Air gap at the pole tips of a dc machine is kept more than that at the centre of the pole mainly to reduce

Answer/ Hint      

Answer : B

Explanation :

26.

Commutation in a dc machine may be explained as a process

Answer/ Hint      

Answer : C

Explanation :

27.

Current in a coil undergoing commutation is not able to get reversed completely by the end of commutation period. It is due to

Answer/ Hint      

Answer : A

Explanation :

28.

Under commutation results in

Answer/ Hint      

Answer : C

Explanation :

29.

In a dc shunt generator working on load, the brushed are moved forward in the direction of rotation, as a result of this commutation will

Answer/ Hint      

Answer : A

Explanation :

30.

In a dc machine the sparking between brushes and commutator surface may be due to

Answer/ Hint      

Answer : D

Explanation :

31.

The brushes are alwys placed along

Answer/ Hint      

Answer : A

Explanation :

32.

In any d.c. generator, the emf generated in the armature is maximum when:

Answer/ Hint      

Answer : B

Explanation :

33.

The method which can be used to improve commutation process is

Answer/ Hint      

Answer : D

Explanation :

34.

The function of interpoles is

Answer/ Hint      

Answer : D

Explanation :

35.

Generators are run in parallel for achieving the advantage of :

Answer/ Hint      

Answer : D

Explanation :

36.

Shunt generators are used where the main requirement is a constant.

Answer/ Hint      

Answer : D

Explanation :

37.

Interpoles are normally connected in :

Answer/ Hint      

Answer : B

Explanation :

38.

In d.c. generator, which loss varies with the load

Answer/ Hint      

Answer : A

Explanation :

39.

The armature of d.c. generator is laminated to

Answer/ Hint      

Answer : C

Explanation :

40.

In d.c. generators , the  cause of rapid brush wear may be:

Answer/ Hint      

Answer : D

Explanation :

41.

In d.c. generators,  lap winding is used for ;

Answer/ Hint      

Answer : C

Explanation :

42.

D.C generator preferred for charging automobiles batteries is:

Answer/ Hint      

Answer : A

Explanation :

43.

The over all efficiency of a d.c. generator lies in the range of :

Answer/ Hint      

Answer : D

Explanation :

44.

The function of an equalizer ring is

Answer/ Hint      

Answer : C

Explanation :

45.

The carbon brushes of DC machines become shorter by wearing out during the running time of the machine. At which length do you have to change the brushes

Answer/ Hint      

Answer : D

Explanation :

46.

A2 KW, 200 V,DC generator will supply a load current of :

Answer/ Hint      

Answer : C

Explanation :

47.

The essential condition for stable parallel operating of two D.C generators having  similar characterstics is that they should have

Answer/ Hint      

Answer : B

Explanation :

48.

D.C. generators are connected to or disconnected from the busbar only under the floating condition. This is done to avoid

Answer/ Hint      

Answer : D

Explanation :

49.

For parallel operation the D.C generators normally preferred are

Answer/ Hint      

Answer : C

Explanation :

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