1. Rotor slot of squirrel cage induction motor are skewed slightly, so as to
a) increase the mechanical strength of rotor
b) make the rotor construction simplex
c) eliminate locking tendency of the rotor and to reduce the noise
d) save the amount of copper required
ans. c
2. In a 3-phase wound rotor induction motor, 3-phase balanced supply is given to the rotor and stator winding is short circuited. The rotor would
a) not run
b) run in the direction of the field
c) run against the direction of rotating field
d) run at half synchronous speed
ans. c
3. The rotor of an induction motor can't run at synchronous speed, if it did so then
a) rotor emf would be zero
b) rotor current would be zero
c) rotor torque would be zero
d) all of these
ans. d
4. A 3-phase induction motor is running at half full load . If the fuse in one of the phases gets burnt, the motor would
a) come to standstill
b) continue running at the same speed
c) continue running at slightly reduced speed
d) continue running at an increased speed
ans. c
5. A 3-phase , 50 Hz , 4-pole squirrel cage induction motor has its stator rewound for 6 poles without any alternations in the rotor. The motor would now run at a speed
a) less than 1000 rpm
b) less than 1500 rpm
c) less than 3000 rpm
d) zero rpm
ans. a
6. The stator of a 3-phase , 4-pole , slip ring induction motor is fed from 50 Hz source and its rotor from 30 Hz source. The motor will run at
a) 1500 rpm
b) 900 rpm
c) zero rpm
d) 2400 rpm
ans. d
7. The capacitor start motor uses
a) paper capacitor
b) electrolytic capacitor
c) air capacitor
d) none of the above
ans. b
8. The value of capacitor in a capacitor start motor controls the
a) starting value
b) speed of the motor
c) efficiency
d) none of the above
ans. a
9. Under no load conditions, the speed of a universal motor is limited by
a) supply frequency
b) supply voltage
c) windage and friction
d) none of the above
ans. c
10. Which of the following motors does not use a centrifugal switch
a) split phase motor
b) capacitor start capacitor run motor
c) shaded pole motor
d) none of the above
ans. c
a) increase the mechanical strength of rotor
b) make the rotor construction simplex
c) eliminate locking tendency of the rotor and to reduce the noise
d) save the amount of copper required
ans. c
2. In a 3-phase wound rotor induction motor, 3-phase balanced supply is given to the rotor and stator winding is short circuited. The rotor would
a) not run
b) run in the direction of the field
c) run against the direction of rotating field
d) run at half synchronous speed
ans. c
3. The rotor of an induction motor can't run at synchronous speed, if it did so then
a) rotor emf would be zero
b) rotor current would be zero
c) rotor torque would be zero
d) all of these
ans. d
4. A 3-phase induction motor is running at half full load . If the fuse in one of the phases gets burnt, the motor would
a) come to standstill
b) continue running at the same speed
c) continue running at slightly reduced speed
d) continue running at an increased speed
ans. c
5. A 3-phase , 50 Hz , 4-pole squirrel cage induction motor has its stator rewound for 6 poles without any alternations in the rotor. The motor would now run at a speed
a) less than 1000 rpm
b) less than 1500 rpm
c) less than 3000 rpm
d) zero rpm
ans. a
6. The stator of a 3-phase , 4-pole , slip ring induction motor is fed from 50 Hz source and its rotor from 30 Hz source. The motor will run at
a) 1500 rpm
b) 900 rpm
c) zero rpm
d) 2400 rpm
ans. d
7. The capacitor start motor uses
a) paper capacitor
b) electrolytic capacitor
c) air capacitor
d) none of the above
ans. b
8. The value of capacitor in a capacitor start motor controls the
a) starting value
b) speed of the motor
c) efficiency
d) none of the above
ans. a
9. Under no load conditions, the speed of a universal motor is limited by
a) supply frequency
b) supply voltage
c) windage and friction
d) none of the above
ans. c
10. Which of the following motors does not use a centrifugal switch
a) split phase motor
b) capacitor start capacitor run motor
c) shaded pole motor
d) none of the above
ans. c
