"220V Cooling Fan" is to provide the use of an alternating power supply: single-phase AC motor is only one winding, the rotor is a squirrel-cage. When single-phase sinusoidal current through the stator winding the motor will produce an alternating magnetic field, the strength and direction of the magnetic field at any time intercropping sine law, but in the spatial orientation is fixed, so called the alternating magnetic field pulsating magnetic field. This alternating pulsating magnetic field can be decomposed into two at the same speed, "220V Cooling Fan" rotational direction opposite to each other rotating magnetic field. Generating two equal-sized in the rotor, the opposite direction of the torque, so that the net torque is zero, so the motor can not rotate. When we use the force of the motor to rotate in one direction, then cutting magnetic field lines motion rotating magnetic field of the rotor and the clockwise rotation becomes smaller; cut magnetic lines rotating magnetic field "220V Cooling Fan" rotor and counter-clockwise rotation direction between movement becomes larger. This balance broke the total electromagnetic torque generated by the rotor will no longer be zero, the rotor will push direction along the spin.