The main source of low power factor at which induction motor
operates is the air gap between the stator and the rotor . This
air gap increases the reluctance between the stator and the
rotor , which enhances the magnetizing current for production
of the given mutual flux between the stator and the rotor for a
given supply voltage . Therefore, the no -load current of an
induction motor becomes 30 to 40 per cent of full -load
current , which is remarkably larger than the no -load current
of a transformer for a given kVA rating. The air gap in an
induction motor should be made small so that the induction
motor gives better performance . The small air gap may result
mechanical problems in addition to the noise and losses at
the slot tooth faces.