A starting circuit for an induction motor is provided whereby a stationary rotor
flux is established then a stored charge supplied to a motor winding in order to
provide a starting torque. Before applying a mains power supply to the motor after
the starting torque has been applied, a back EMF is sensed, directly or indirectly,
to provide an indication that the rotor is turning before the mains supply is connected
to the motor. This provides a reliable and simple method for ensuring that a mains
supply may be safely connected to the motor.
