Shaded pole motor at half the voltage, what will happen?

[neazoi]

I have a 240vAC 18W shaded pole motor out of a microwave oven fan.
What will happen if I run it on half the voltage (120vAC)?

The motor runs on 120vAC (much cooler), but what will happen to the speed of it?
The motor is in theory a synchronous motor (as far as I know), so even if one runs it at half voltage, it should run at the same speed (a bit less than 50Hz) due to the AC frequency being the same.
Is only the torque reduced by running the motor at half voltage and not it's speed?

 

[FvM]

The fact that a shaded pole motor always run at a speed below synchronous speed (3000 rpm with single pole pair) proves that it's an asynchronous rather than synchronous motor. A synchronous motor runs either at exact synchronous speed or is stalled.

Your description is nevertheless correct. Torque is considerably reduced (with about V square dependency), unloaded speed only slightly.

 

[Easy peasy]

as above torque, proportional to current ....

 

[FvM]

Here's the general torque characteristc of an induction motor, shown for 50, 70 and 100 % of rated voltage. Copied from Rolf Fischer, Elektrische Maschinen, Hanser 1992

 

[crutschow]

even if one runs it at half voltage, it should run at the same speed

With the fan load, it will likely run significantly slower, with a lot of slip from the theoretical synchronous value.