A shaded-pole single-phase motor — the simplest and cheapest induction motor. Instead of a start winding, part of each pole is encircled by a short-circuited copper ring (a "shade"). This ring delays the flux build-up in its part of the pole, so the field appears to "sweep" from the unshaded to the shaded part — a weak travelling field that starts the rotor. The direction of rotation is fixed by which side is shaded and cannot be changed. The starting torque and efficiency are low, so these motors are used only in small appliances: fans, extractor hoods, microwave ovens. The model shows the torque M, the speed n and the current in the shading ring.
This page is a utility for simulating shaded-pole single-phase motor online with specified initial values.
Using the model. Close the switch to apply the single-phase voltage — the motor starts by itself thanks to the shading rings (their current I(ring) is shown in the caption); note how small the starting torque is. Use the "supply voltage" slider and the series rheostat to change the supply: lowering the voltage smoothly reduces the speed — the usual way of controlling such motors. The "load torque" slider sets the load. The scopes show the voltage U(motor) and the current I(motor).
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