A motor capacitor, such as a start capacitor or run capacitor is an electrical capacitor that alters the current to one or more windings of a single-phase alternating-current induction motor to create a rotating magnetic field. The Capacitor Motor, which belongs to the Single-phase Induction motor, is explained in this video.
In a single-phase motor all of a motor’s coils begin their cycle at the same time. The magnetic field doesn’t rotate, so the rotor can’t move. Engineers worked around this by using a separate starter coil in series with a capacitor. Watch the video from learnchannel for more info:
Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans.A single phase induction motor requires separate starting circuitry to provide a rotating field to the motor.
The normal running windings within such a single-phase motor can cause the rotor to turn in either direction, so the starting circuit determines the operating direction.