Single-Phase Induction Motors
The single-phase electric motor operates beneath the same principle as the polyphase engine, except that the rotating magnetic field effect generated by the stator does not exist until running rpm is reached. Since no beginning torque is offered, a design system is included to start the motor. These are the various designations:
Torque-Speed Curves of Different Single-Phase Induction Motors
Shaded-pole: Have only one main winding and no start winding. This configuration causes a change of the applied magnetic field in relationship to the rotor, creating stating torque. Applications include fans and small appliances.
Split-Phase (induction start electric motor)
Has two units of stator windings. The “start” windings are positioned 90 degrees to the “run” windings and shift the magnetic field of the stator, inducing starting torque. Applications include small grinders, small fans, and blowers.
The most typical single-phase motor found in industrial applications. It is a modified split-phase motor with a capacitor in series with the start winding to provide a start boost. Program include small conveyors, large blowers, pumps, and direct-drives.
Uses identical main and auxiliary windings with a capacitor to chain sprocket supply starting torque. They will be the most reliable single-phase engine because no centrifugal beginning switch is necessary. Applications include followers and pumps in HVAC and refrigeration industries.