Chinese electric fan motor. Electric fans generally use single-phase crossover or shaded pole motors. Shaded pole motors have simple structure, easy production, convenient maintenance, and low cost, but they have small starting torque, poor overload capacity, and low efficiency. They are only used in small-sized desktop fans. Capacitor-operated motors have high power factor, good starting performance, high efficiency, strong overload capacity, and stable operation. At present, most electric fans use capacitor-operated motors.
a. The working principle of a capacitor-operated motor. The capacitor-operated motor is composed of a stator and a squirrel-cage rotor. Main winding and auxiliary winding are embedded on the stator. The main and auxiliary windings form a 900 electrical angle to each other in space. The secondary winding is connected in series with a running capacitor and connected to the main winding and connected to the circuit. When the primary and secondary windings are connected to single-phase alternating current, the primary winding generates a pulsating magnetic field. Under the action of the capacitor, the secondary winding produces a phase lead of about 90' Pulsating magnetic field in electrical angle. These two pulsating magnetic fields synthesize a rotating magnetic field, which drives the rotor to start operation. Because the capacitor is always connected to the circuit when it is running, this kind of motor is called a capacitor-running motor. In fact, it is a two-phase running motor.
