multiple choice questions on induction machines # 18

                                  Hi friends, this post is about induction motor objectives. These are some of the questions asked in previous question papers of Gate, IES and other competitive exams. check out and comment if you have any doubts....


objectives on induction machines # 18


1) A Squirrel Cage induction motor is not favored when.......................is the main consideration
A) initial cost
B) maintenance cost
C) high starting torque
D) higher efficiency and higher power factor

Ans:C

2) A slip ring induction motor is recommended for applications requiring
A) high starting torque
B) variable speed operation
C) frequent starting, stopping and reversing operations
D) all of the above features

Ans:D

3) Which of the following ac motor is widely used?
A) Squirrel Cage induction motor
B) Slip-ring induction motor
C) Double cage induction motor
D) Synchronous motor

Ans:A

4) Induction motors, Over synchronous motors, have the advantages of
A) being self starting
B) having no requirement for dc excitation
C) possibility of speed control to small extent
D) simplicity and lower cost
E) all of the above

Ans:E

5) Unbalanced 3-phase voltage supply to an induction motor causes excessive heating of
A) rotor
B) stator
C) rotor shaft
D) none of these

Ans:A

6) Unbalanced supply voltage given to a 3-phase, delta connected induction motor will cause
A) zero sequence currents
B) less heating of motor
C) negative sequence component current
D) all the above

Ans:C

7) Single phase preventer
A) suppresses negative sequence component currents
B) compensates for voltage drops
C) provides protection in the event of non-availability of one of the phases
D) none of the above

Ans:C

8) Increase in supply voltage to a 3-phase induction motor will not cause
A) decrease in input current and so reduction in copper losses
B) increase in torque
C) decrease in speed as well as in core loss
D) operating temperature abnormally higher owing to increase in core loss

Ans:C

9) Decrease in supply voltage to a 3-phase induction motor will not cause
A) any difficulty in accelerating the load
B) increase in torque
C) decrease in speed as well as in core loss
D) increase in stator as well as rotor currents
E) operating temperature abnormally high owing to increase in core loss

Ans:B

10) A 3-phase induction motor is operating at its rated torque. If the supply voltage falls to 75% of its normal value
A) the motor will get heated up to inadmissible extent after some time
B) the motor will stop
C) the slip will decrease
D) the stator and rotor current will decrease

Ans:A

                 These are some of the objectives of induction machines.. If you like my post share it with your friends and subscribe for latest updates..

Previous
Next Post »