MCQs on Induction motor
1. An induction motor works with
- dc only
- ac only
- ac and dc both
- none of these
2. Uneven gap in an induction motor is likely to cause
- heating of motor
- unbalancing of motor shaft
- both (1) and (2)
- none of these
3. In a 3-phase wound rotor induction motor, the short circuit gear is used to short circuit the
- stator phases of the motor
- rotor at slip rings
- starting resistances in the starter
- none of the above
4. The rotor of a 3-phase wound rotor induction motor is provided with
- single phase-winding
- three phase winding
- heavy copper or aluminium bars placed in rotor slots
- heavy short-circuited end rings
5. Induction motors normally use diecast aluminium rotor because aluminium is
- cheaper in cost
- lighter in weight
- easy to cast owing to its low melting point and is easily available
- of low resistivity
6. The stator core of a 3-phase induction motor is laminated in order to reduce the
- eddy current loss
- hysteresis loss
- both eddy current and hysteresis loss
- weight of the stator
7. In a 3-phase squirrel cage induction motor
- rotor conductors are short circuited through end rings
- rotor conductor ends are short circuited through slip rings
- rotor conductors are kept open
- none of the above
8. The induction motor shaft is made of
- mild steel
- cast iron
- stainless steel
- aluminium
9. The induction motor shaft should be
- hollow
- stiff
- flexible
- any of these
10. The stator frame of an induction motor is used to
- hold the armature stampings in position
- ventilate the armature
- protect the whole machine
- provide return path for the flux