multiple choice questions on dc generator # 8

Hi readers this is another post on dc generators check out and comment if you have any doubts....

1) In lap winding, the number of brushes is always ..............the number of poles
A) double
B) same as
C) half
D) none of these

Ans:B

2) A lap wound dc machine has 400 conductors and 8 poles. The voltage induced per conductor is 2 V. The machine generates the voltage of
A) 100 V
B) 200 V
C) 400 V
D) 800 V

Ans:A

3) A pole generator with 16 coils has a two layer winding. The pole pitch is
A) 32
B) 16
C) 8
D) 4

Ans:C

4) welding generator will have
A) lap winding
B) wave winding
C) either lap or wave winding
D) none of these

Ans:A

5) The armature of dc machine is laminated
A) to reduce the hysteresis loss
B) to reduce the eddy current loss
C) to reduce the mass
D) to reduce the inductance

Ans:B

6) A 250 V dc generator is run at rated speed with no excitation. The open circuit voltage will be
A) zero
B) very small, say about 2 or 3 V
C) about 100 V
D) 250 V

Ans:B

7) The armature resistance of a 6-pole lap wound dc machine is 0.05𝜴. If the armature is rewound as a wave winding, what is the armature resistance?
A) 0.45𝜴
B) 0.30𝜴
C) 0.15𝜴
D) 0.10𝜴

Ans:A

8) Minimum number of coils for 400 V, 6-pole lap connected dc machine for a maximum voltage of 15 V between adjacent commutator segments should be
A) 80
B) 160
C) 200
D) 400

Ans:B

9) Generally the no load losses of an electric machine is represented in its equivalent circuit by a
A) parallel resistance with a low value
B) series resistance with a low value
C) parallel resistance with a high value
D) series resistance with a high value

Ans:C

10) For a P-pole machine, the relation between electrical and mechanical degrees is given by
A) 𝚹elec = (2/P) 𝚹mech
B) 𝚹elec = (4/P) 𝚹mech
C) 𝚹elec = P 𝚹mech
D) 𝚹elec = (P/2) 𝚹mech

Ans:D

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