1. The complete circle diagram of induction motor can be drawn with the help of data found from ?

no-load test

blocked rotor test

stator resistance test

all of the above

Answer: all of the above


2. The circle diagram for an induction motor cannot be used to determine ?


power factor



Answer: efficiency


3. Temperature of the stator winding of a three-phase induction motor is obtained by ?

resistance rise method

thermometer method

embedded temperature method

all above methods

Answer: all above methods


4. The torque of an induction motor is ?

directly proportional to slip

inversely proportional to slip

proportional to the square of the slip

none of the above

Answer: directly proportional to slip


5. If there is an open circuit in the rotor of a squirrel cage induction motor ?

rotor will overheat

line fuses will blow

motor will be noisy

motor will not start

Answer: motor will not start


6. The pull-out torque for a normal squirrel cage induction motor usually occurs at a percentage slip of about ?

10 to 16 per cent

20 to 25 per cent

35 to 46 per cent

50 to 60 per cent

Answer: 20 to 25 per cent


7. ln case of a 3-phase wound rotor induction motor an increase in rotor resistance affects the motor performance in the following way ?

the motor efficiency decreases

the motor efficiency increases

starting current decreases

starting current increases

Answer: starting current decreases


8. The difference between the synchronous speed and the actual speed of an induction motor is known as ?




back lash

Answer: slip


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

diameter of shaft

size of frame

presence of slip ring

direction or rotation

Answer: presence of slip ring


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

Ball bearing

Needle bearing

Plummer block

Bush bearing

Answer: Ball bearing