Most induction motor used in home appliances and industrial motion-control systems are AC induction motors. The motors consist of a stationary housing known as the stator and a rotating interior part known as a rotor. The AC single-phase induction motor is not self-starting. The types of starting mechanisms can be used to divide these motors into categories.
Capacitor Start Motors
The capacitor start ACinduction motor is a modified split-phase design. A capacitor is wired in series with the starter winding. This gives a surge to help start the motor. This motor has a switch that will disconnect the starter circuit when the motor reaches 75 percent of the rated speed. This motor reaches approximately 200 percent to 400 percent of the rated torque. When requiring the starting torque to be less, the capacitor can be replaced by a resistor to lower the cost.
Shaded-Pole Motor
The shaded-pole ACinduction motor uses continuous loops of copper wire on a small part of the motor poles. This shaded area causes the magnetic field to lag behind. The difference between the two fields causes the shaft to move. The simple inexpensive designs makes this motor popular for high-production applications. In general, it is cheaper to replace this motor than repair it.
