What are the safety precautions for handling a shaded-pole motor?

[mishima]

Hi, I was looking for some information on how to safely handle a shaded-pole motor of the sort found inside electric can openers and plugged into the mains. I was not sure of the voltages present on the shaded pole coils in particular.

 

[CWatters]

For safety you should assume all exposed metalwork _might_ be at mains potential.

 

[berkeman]

Also, @mishima since electric can openers are usually designed as double-insulated devices with 2--prong power cords, the AC Mains motor is likely not isolated from Hot/Neutral (but the mechanical assembly allows for external metal parts of the can opener to be doubly-insulated from the AC Mains input). This means that you should be using an AC Mains Isolation Transformer if you are working with such a motor. Are you familiar with Isolation Transformers?

Interesting assembly view of a typical can opener:

https://patentimages.storage.googleapis.com/pages/US3178813-2.png

 

[mishima]

That is an interesting example from the 1960s, and interesting to compare to a modern version. The belt drives are replaced with a compound (plastic) gear train that enables just one motor to get the job done.

I'm not familiar with isolation transformers because I've always been too scared to work with AC. Sounds like a good starting point for study.

 

[jim hardy]

I was not sure of the voltages present on the shaded pole coils in particular.

typical shaded pole winding is just a turn or two , usually copper, wrapped around part of the core. Since it's a shorted turn it can't develop voltage.

Only way there'd be voltage present is if there's a short between the main coil and the iron core making the entire assembly "hot"

Does yours resemble this ?
from: http://www.johnsonelectric.com/en/resources-for-engineers/ac-motors/principle-of-operation

I played with lots of them as a kid, mostly affixing model airplane propellers to make handheld fans. Good thing they're inherently safe.

Still, check for voltage before you grab hold of it.

old jim

 

[mishima]

That's the one, though mine has 2 shaded coils. And thanks, that makes sense about no voltages being on them.

 

[jim hardy]

That's the one, though mine has 2 shaded coils.

Sure ! Symmetry... My sketch above should have shading rings on both poles.
https://en.wikipedia.org/wiki/Shaded-pole_motor