shadedpole

Shaded-pole motor, also called shaded-pole induction motor, is one of the simplest types of single-phase induction motors. It uses a stator with main windings and a partial copper ring, known as a shading coil, around part of each pole. When AC current energizes the main winding, the shading coil carries a current that lags the main flux. This creates a secondary magnetic flux that is shifted in time around the pole face, producing a weak rotating magnetic field. The rotor is drawn into rotation by this rotating field and continues to run at a speed slightly below synchronous speed, with slip determined by load.

Construction and operation: The stator core is laminated and houses a single winding per phase. Each pole is partly covered by a shading coil, typically a short-circuited copper loop. The shading coil is inexpensive, robust, and requires little maintenance. The resulting rotating field is what gives the motor its starting and running torque, though both are relatively modest compared with other motor types.

Performance and applications: Shaded-pole motors are compact, durable, and inexpensive, making them common in small household appliances, fans, and ventilation devices. They offer self-starting operation but exhibit relatively low starting torque, poor efficiency, and a weak power factor, especially at light loads. Their speed is modest and decreases with load; the design is suitable for low-power, low-load applications where simplicity and cost are prioritized.

Variants and context: The term refers to motors that use shading coils on each pole. They are often chosen for simple, low-cost tasks rather than demanding motor applications.