Electrical Engineering ⇒ Topic : Shaded-pole motor

SHADED-POLE INDUCTION MOTOR

A shaded-pole motor is one of the simplest and cheapest of manufactured motors. It is essentially an induction machine, since its squirrel-cage rotor receives power in much the same way as does the rotor of the polyphase induction motor. There is, however, one extremely important difference between the two. Whereas the polyphase induction motor creates a true revolving field, in the sense that it is constant in magnitude and rotates at synchronous speed completely round the entire core, the field of the shaded-pole motors not constant in magnitude but merely shifts from one side of the pole to the other. Because the shaded-pole motor does not create a true revolving field, the torque is not uniform but varies from instant to instant.