electrical

Three Phase Induction Motor MCQ Questions and Answers Page - 5

1.

The power factor of a 3-phase induction motor is likely to be maximum when it will operate at

Answer/ Hint      

Answer : A

Explanation :

2.

The power factor of a lightly loaded induction motor is quite low because

Answer/ Hint      

Answer : A

Explanation :

3.

In a 3-phase induction motor when the load is increased from light load

Answer/ Hint      

Answer : B

Explanation :

4.

An induction motor always operators on lagging power factor this is due to

Answer/ Hint      

Answer : D

Explanation :

5.

Open circuit test is usually conducted on

Answer/ Hint      

Answer : C

Explanation :

6.

In which of the following tests to be conducted on induction motors, reduced voltage is applied

Answer/ Hint      

Answer : A

Explanation :

7.

Blocked rotor test of an induction motors corresponds, in case of a transformer to

Answer/ Hint      

Answer : D

Explanation :

8.

What is the shunt resistance component in equivalent circuit obtained by no-load test of an induction motor representative of?

Answer/ Hint      

Answer : B

Explanation :

9.

Under no-load condition, if the applied voltage to an induction motor is reduced from the rated voltage to half the rate value

Answer/ Hint      

Answer : B

Explanation :

10.

The core losses, and friction and windage losses in case of an induction motor are determine from the _____test

Answer/ Hint      

Answer : A

Explanation :

11.

Short –circuit test is performed on an induction motor to determined

Answer/ Hint      

Answer : D

Explanation :

12.

Circle diagram is employed to determine the performance of a/an

Answer/ Hint      

Answer : B

Explanation :

13.

The power scale of circle diagram of an induction motor is determined from ____test data only

Answer/ Hint      

Answer : C

Explanation :

14.

In the circle diagram of an induction motor the diameter of the circle represents the

Answer/ Hint      

Answer : A

Explanation :

15.

Circle diagram of an induction motor can be used to determine its

Answer/ Hint      

Answer : D

Explanation :

16.

An induction motor is said to be crawling when

Answer/ Hint      

Answer : A

Explanation :

17.

Zero sequence impedance of a 3-phase cage induction motor is due to

Answer/ Hint      

Answer : B

Explanation :

18.

An induction motor when started on load does not accelerate up to full speed but run at 1/7th of the rated speed. The motor is said to be

Answer/ Hint      

Answer : C

Explanation :

19.

Crawling in an induction motor is due to

Answer/ Hint      

Answer : C

Explanation :

20.

The crawling in the induction motor is caused by

Answer/ Hint      

Answer : D

Explanation :

21.

The phenomenon of crawling in a 3-phase induction motor may be due to

Answer/ Hint      

Answer : B

Explanation :

22.

In an induction motor, when the number of stator slots is equal to an integral multiple of rotor slots,

Answer/ Hint      

Answer : D

Explanation :

23.

Crawling of induction motor occurs due to

Answer/ Hint      

Answer : D

Explanation :

24.

Presence of 5th harmonics in induction motor causes

Answer/ Hint      

Answer : C

Explanation :

25.

The cogging occurs in induction motors due to

Answer/ Hint      

Answer : B

Explanation :

26.

cogging of induction motors occurs at

Answer/ Hint      

Answer : C

Explanation :

27.

In an induction motor, if the air gap is increased

Answer/ Hint      

Answer : C

Explanation :

28.

An increase in number of poles of an induction motor results in

Answer/ Hint      

Answer : A

Explanation :

29.

Increase in length of air gap in an induction motor causes

Answer/ Hint      

Answer : D

Explanation :

30.

An induction motor with larger number of slots has ____overload capacity

Answer/ Hint      

Answer : B

Explanation :

31.

Type of bearing used for 25 H.P motor is

Answer/ Hint      

Answer : A

Explanation :

32.

When as induction motor is switched on the rotor frequency is

Answer/ Hint      

Answer : D

Explanation :

33.

A wound rotor induction motor can be distinguished from squirrel cage induction motor by

Answer/ Hint      

Answer : C

Explanation :

34.

Which of the following A.C motor is used for industrial applications?

Answer/ Hint      

Answer : B

Explanation :

35.

Which of the following type of bearing is generally used to support the rotor of an induction motor?

Answer/ Hint      

Answer : A

Explanation :

36.

When a squirrel cage induction motor fails to start which of the following could not be the reason for the same?

Answer/ Hint      

Answer : C

Explanation :

37.

Under which method of starting an induction motor is expected to take largest current?

Answer/ Hint      

Answer : A

Explanation :

38.

The stator of 5 H.P induction motor is provided with

Answer/ Hint      

Answer : C

Explanation :

39.

The direction of rotation of a 3-phase induction motor can be reversed by

Answer/ Hint      

Answer : A

Explanation :

40.

A wound rotor induction motor is usually not selected when

Answer/ Hint      

Answer : B

Explanation :

41.

Which of the following features of induction motor helps in preventing cogging of motor?

Answer/ Hint      

Answer : A

Explanation :

42.

The number of slip rings on a squirrel cage induction motor is

Answer/ Hint      

Answer : D

Explanation :

43.

Synchronous wattage of induction motor means

Answer/ Hint      

Answer : B

Explanation :

44.

If stator voltage of a squirrel cage induction motor is reduced to one-half its normal value, its starting current is reduced to ……percent of its full-voltage value

Answer/ Hint      

Answer : C

Explanation :

45.

If stator voltage of a squirrel cage induction motor is reduced 50% of its rated value, torque developed is reduced by ……percent of its full-load value.

Answer/ Hint      

Answer : B

Explanation :

46.

In a 3-phase induction motor which of the following statements, regarding frequency of induced rotor e.m.f is incorrect?

Answer/ Hint      

Answer : A

Explanation :

47.

Which of the following motors are used frequently?

Answer/ Hint      

Answer : A

Explanation :

48.

The starting torque of the slip ring induction motor can be increased by

Answer/ Hint      

Answer : B

Explanation :

49.

The stator frame in an induction motor is used

Answer/ Hint      

Answer : C

Explanation :

50.

The noise and tooth pulsating losses can be minimized by using

Answer/ Hint      

Answer : A

Explanation :

51.

If the rotor is open in a squirrel cage motor, it

Answer/ Hint      

Answer : C

Explanation :

52.

The value of average flux density in air gap in an induction motor, should be small

Answer/ Hint      

Answer : C

Explanation :

53.

An induction motor with large number of slots has

Answer/ Hint      

Answer : B

Explanation :

54.

In an induction motor the pulsating losses and noise can be reduced by using

Answer/ Hint      

Answer : B

Explanation :

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