3 - Phase Induction Motors - Electrical Engineering (MCQ) questions and answers

1)   The resultant flux in an induction motor is equal to the

a. Maximum value of flux due to any phase
b. Twice of the maximum value of flux due to any phase
c. 0.5 times the maximum value of flux due to any phase
d. 1.5 times the maximum value of flux due to any phase
Answer  Explanation 

ANSWER: 1.5 times the maximum value of flux due to any phase

Explanation:
No explanation is available for this question!


2)   The frequency of rotor current in an induction motor is

a. slip times the frequency of stator current
b. slip times the frequency of supply
c. One by slip times the frequency of stator current
d. One by slip times the frequency of supply
Answer  Explanation 

ANSWER: slip times the frequency of supply

Explanation:
No explanation is available for this question!


3)   Slip ring induction motor has

a. Low starting torque
b. Medium starting torque
c. High starting torque
d. None of these
Answer  Explanation 

ANSWER: High starting torque

Explanation:
No explanation is available for this question!


4)   Slip ring induction motor are employed only for

a. Speed control
b. High starting torque
c. Both (a) and (b)
d. None of these
Answer  Explanation 

ANSWER: Both (a) and (b)

Explanation:
No explanation is available for this question!


5)   The advantage of skewing in induction motor is / are

a. Motor runs smoothly as the magnetic hum is reduced
b. The tendency of the rotor teeth to remain under the stator teeth due to direct magnetic attraction is reduced
c. More uniform torque is obtained while running
d. All of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!


6)   The frequency of the induced emf in an induction motor is

a. Greater than the supply frequency
b. Lesser than the supply frequency
c. Same as the supply frequency
d. None of these
Answer  Explanation 

ANSWER: Same as the supply frequency

Explanation:
No explanation is available for this question!


7)   Slip of an induction motor increases with

a. increase in current and decrease in torque
b. increase in current and torque
c. decrease in current and torque
d. decrease in current and increase in torque
Answer  Explanation 

ANSWER: increase in current and torque

Explanation:
No explanation is available for this question!


8)   In an induction motor, rotor speed is always

a. Less than the stator speed
b. More than the stator speed
c. Equal to the stator speed
d. None of these
Answer  Explanation 

ANSWER: Less than the stator speed

Explanation:
No explanation is available for this question!


9)   In induction motor, greater the number of poles

a. Lesser the speed
b. Greater the speed
c. Lesser the frequency
d. All of these
Answer  Explanation 

ANSWER: Lesser the speed

Explanation:
No explanation is available for this question!


10)   For induction motors,

a. Should be essentially a constant speed motor
b. Its speed reduces to some extent with increase in load
c. Does not need to be synchronized
d. All of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!