Induction Motor MCQ: Induction Motors MCQs with Answers

Induction Motor MCQ. Multiple Choice Questions and Answers in Electrical Engineering related to Induction Motor.

 

Induction Motor MCQ

 

The rotor of an induction motor runs at ?

A. synchronous speed
B. below synchronous speed
C. above synchronous speed
D. any of the above

View Answer

B. below synchronous speed

 

An induction motor can run at synchronous speed when ?

A. it is run on load
B. it is run in reverse direction
C. it is run on voltage higher than the rated voltage
D. e.m.f. is injected in the rotor circuit

View Answer

D. e.m.f. is injected in the rotor circuit

 

Slip ring motor is preferred over squirrel cage induction motor where ?

A. high starting torque is required
B. load torque is heavy
C. heavy pull out torque is required
D. all of the above

View Answer

A. high starting torque is required

 

Reduced voltage starter can be used with ?

A. slip ring motor only but not with squirrel cage induction motor
B. squirrel cage induction motor only but not with slip ring motor
C. squirrel cage as well as slip ring induction motor
D. none of the above

View Answer

C. squirrel cage as well as slip ring induction motor

 

In induction motor, percentage slip depends on ?

A. supply frequency
B. supply voltage
C. copper losses in motor
D. none of the above

View Answer

C. copper losses in motor

 

Induction Motor MCQ

 

A squirrel cage induction motor is not selected when ?

A. initial cost is the main consideration
B. maintenance cost is to be kept low
C. higher starting torque is the main consideration
D. all above considerations are involved

View Answer

C. higher starting torque is the main consideration

 

In a squirrel cage motor the induced e.m.f. is ?

A. dependent on the shaft loading
B. dependent on the number of slots
C. slip times the stand still e.m.f. induced in the rotor
D. none of the above

View Answer

C. slip times the stand still e.m.f. induced in the rotor

 

The torque developed by a 3-phase induction motor least depends on ?

A. rotor current
B. rotor power factor
C. rotor e.m.f.
D. shaft diameter

View Answer

D. shaft diameter

 

In case of 3-phase induction motors plugging means ?

A. pulling the motor directly on line without a starter
B. locking of rotor due to harmonics
C. starting the motor on load which is more than the rated load
D. interchanging two supply phases for quick stopping

View Answer

D. interchanging two supply phases for quick stopping

 

The stating torque of the slip ring induction motor can be increased by adding ?

A. external inductance to the rotor
B. external resistance to the rotor
C. external capacitance to the rotor
D. both resistance and inductance to rotor

View Answer

B. external resistance to the rotor

 

Induction Motor MCQ

 

In an induction motor the relationship between stator slots and rotor slots is that ?

A. stator slots are equal to rotor slots
B. stator slots are exact multiple of rotor slots
C. stator slots are not exact multiple of rotor slots
D. none of the above

View Answer

C. stator slots are not exact multiple of rotor slots

 

The starting torque of a 3-phase squirrel cage induction motor is ?

A. twice the full load torque
B. 1.5 times the full load torque
C. equal to full load torque
D. None of the above

View Answer

B. 1.5 times the full load torque

 

Low voltage at motor terminals is due to ?

A. inadequate motor wiring
B. poorely regulated power supply
C. any one of the above
D. none of the above

View Answer

C. any one of the above

 

A 3-phase slip ring motor has ?

A. double cage rotor
B. wound rotor
C. short-circuited rotor
D. any of the above

View Answer

B. wound rotor

 

Size of a high speed motor as compared to low speed motor for the same H.P. will be ?

A. bigger
B. smaller
C. same
D. any of the above

View Answer

B. smaller

 

Induction Motor MCQ

 

Slip of an induction motor is negative when ?

A. magnetic field and rotor rotate in opposite direction
B. rotor speed is less than the synchronous speed of the field and are in the same direction
C. rotor speed is more than the synchronous speed of the field and are in the same direction
D. none of the above

View Answer

C. rotor speed is more than the synchronous speed of the field and are in the same direction

 

The speed of a squirrel-cage induction motor can be controlled by all of the following except ?

A. changing supply frequency
B. changing number of poles
C. changing winding resistance
D. reducing supply voltage

View Answer

C. changing winding resistance

 

The injected e.m.f. in the rotor of induction motor must have ?

A. zero frequency
B. the same frequency as the slip frequency
C. the same phase as the rotor e.m.f.
D. high value for the satisfactory speed control

View Answer

B. the same frequency as the slip frequency

 

The good power factor of an induction motor can be achieved if the average flux density in the air gap is ?

A. absent
B. small
C. large
D. infinity

View Answer

B. small

 

Induction Motor MCQ

 

Star-delta starting of motors is not possible in case of ?

A. single phase motors
B. variable speed motors
C. low horse power motors
D. high speed motors

View Answer

A. single phase motors

 

A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be ?

A. 200 Hz
B. 50 Hz
C. 2 Hz
D. 0.2 Hz

View Answer

C. 2 Hz

 

In medium sized induction motors, the slip is generally around ?

A. 0.04%
B. 0.4%
C. 4%
D. 14%

View Answer

C. 4%

 

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