AC "220V AC Cooling Fan" is to provide the use of alternating power, only a single-phase motor winding. When single-phase sinusoidal current through the stator windings, the motor will produce an alternating magnetic field, the strength and direction of the magnetic field changes with time do sine law, but "220V AC Cooling Fan" in the spatial orientation is fixed, so they this magnetic field is called alternating pulsating magnetic field. When we use the force of the motor to rotate in one direction, movement of the rotating magnetic field cutting magnetic lines "220V AC Cooling Fan" and the clockwise direction of the rotor becomes smaller; cutting magnetic field lines of the rotor and the rotating magnetic field between the counter-clockwise direction of rotation becomes large.