Multiple Choice Questions Of Synchronous Generator Part 1

Hello Engineers.

1. In an alternator, voltage drops occurs in

(A) armature resistance only
(B) armature resistance and leakage reactance
(C) armature resistance, leakage reactance and armature reaction
(D) armature resistance, leakage reactance, armature reaction and earth connections.

Ans : C

2. As the speed of an alternator increases

(A) the frequency increases
(B) the frequency decreases
(C) the frequency remains constant but power factor decreases
(D) none of the above.

Ans : A

3. The armature reaction of an alternator influences

(A) windage losses
(B) operting speed
(C) generated voltage per phase
(D) waveform of voltage generated.

Ans : C

4. The power output of an alternator is 40 kW and KVAR component is – 25. What will be the value of tanφ (φ being the power factor angle) ?

(A) 0.625 lagging
(B) 0.625 leading
(C) 0.375 lagging
(D) 0.375 leading.

Ans: B

5. If the input to the prime mover of an alternator is kept constant but the excitation is changed then the

(A) reactive component of the output is changed
(B) active component of the output is changed
(C) power factor of load remains constant.

Ans : A

6. In synchronous alternator, which of the following coils will have emf closer to sine waveform ?

(A) concentrated winding in full pitch coils
(B) concentrated winding in short pitch coils
(C) distributed winding in full pitch coils
(D) distributed winding in short pitch coils.

Ans : D

7. In order to reduce the harmonics in the emf generated in an alternator

(A) slots are skewed
(B) salient pole tips are chamfered
(C) winding is well distributed
(D) all of the above.

Ans  : D

8. In alternators, the distribution factor is defined as the ratio of emfs of

(A) distributed winding to connected winding
(B) full pitch winding to distributed winding
(C) distributed winding to full pitch winding
(D) concentrated winding to distributed winding.

Ans : A

9. The windings for an alternator are
I. 36 slots, four poles, span 1 to 8
II. 72 slots, six poles, span 1 to 10
III. 96 slots, six poles, span 1 to 12.

The windings having pitch factors of more than 0.9 are

(A) I and II only
(B) II and III only
(C) I and II only
(D) I, II and III.

Ans : A

10. Zero power factor method of an alternator is used to find its

(A) field resistance
(B) armature resistance
(C) efficiency
(D) voltage regulation.

Ans : D

If you have any problem with any question then comment below.

Thanks.