Single-Phase Induction Motors

Single-Phase Induction Motors
The single-phase engine operates beneath the same principle as the polyphase motor, except that the rotating magnetic field effect chain sprocket produced by the stator will not exist until running rpm is reached. Since no beginning torque is available, a design mechanism is included to begin the motor. They 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 shift of the used magnetic field in relationship to the rotor, creating stating torque. Applications include fans and small appliances.

Split-Phase (induction start engine)
Has two pieces of stator windings. The “start” windings sit 90 degrees to the “run” windings and shift the magnetic field of the stator, inducing starting torque. Applications include little grinders, small followers, and blowers.

Capacitor-Start
The most common 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, huge blowers, pumps, and direct-drives.

Permanent-Split-Capacitor (PSC)
Uses identical primary and auxiliary windings with a capacitor to supply starting torque. They will be the most reliable single-phase electric motor because no centrifugal starting switch is required. Applications include fans and pumps in HVAC and refrigeration industries.