1. A Double cage induction motor has:
a) two series windings in stator
b) two series windings in rotor
c) two series windings in stator
d) two parallel windings in rotor
2. In double cage induction motor the resistance of the upper cage is __ that of inner cage:
a) equal to
b) 4 to 5 times of
c) one fourth of
d) none of these
3. Slip ring induction motors have the advantage of:
a) High starting torque and high over load capacity
b) Very ruggged construction
c) Cheap in cost
d) Both (a) and (b)
4. Advantages of induction motor compared to synchronous motors are:
a) Self starting
b) Having no requirement for the excitation
c) possibility of speed control to some extent and cheaper
d) All the above
5. Unbalanced three phase voltage supply to an induction motor causes excess heating of:
a) rotor
b) rotor shaft
c) stator
d) both rotor and stator
6. Squirrel cage induction motors are not favored when __ is considered:
a) initial cost
b) low starting current
c) high starting torque
d) both (a) and (b)
7. The starting torque of induction motor varies as:
a) f
b) 1/f 2
c) 1/f
d) f 2
a) two series windings in stator
b) two series windings in rotor
c) two series windings in stator
d) two parallel windings in rotor
2. In double cage induction motor the resistance of the upper cage is __ that of inner cage:
a) equal to
b) 4 to 5 times of
c) one fourth of
d) none of these
3. Slip ring induction motors have the advantage of:
a) High starting torque and high over load capacity
b) Very ruggged construction
c) Cheap in cost
d) Both (a) and (b)
4. Advantages of induction motor compared to synchronous motors are:
a) Self starting
b) Having no requirement for the excitation
c) possibility of speed control to some extent and cheaper
d) All the above
5. Unbalanced three phase voltage supply to an induction motor causes excess heating of:
a) rotor
b) rotor shaft
c) stator
d) both rotor and stator
6. Squirrel cage induction motors are not favored when __ is considered:
a) initial cost
b) low starting current
c) high starting torque
d) both (a) and (b)
7. The starting torque of induction motor varies as:
a) f
b) 1/f 2
c) 1/f
d) f 2
8. The size of high speed motor will be __ compared to that of low speed motor of the same rating
a) high
b) low
c) cannot be predictable
d) none of the above
9. Under which of the following starting methods an induction motor draws high starting currents:
a) Star-delta starter
b) Auto transformer starter
c) Direct on line starter
d) Reduced voltage starter
10. Which of the following induction motor will be operating at lowest value of the power factor:
a) 7.5 kW, 950 rpm
b) 7.5 kW, 1440 rpm
c) 15 kW, 950 rpm
d) 15 kW, 1440 rpm
