[Joe Weldor]

I just picked up a cute little 115VAC single phase induction motor that I would like to use on a new spindle I’m building. It was made for a military application I believe, none the less, there aren’t any openings on this thing for the heat to escape. This brings me (finally) to my question. I wired it according to the diagram on the motor. Starts and runs fine and very, very quiet. After letting it run about 15 minutes it seemed to get a little hot. I turned it off when it got up to 75deg C. Checked the amp draw when it was running and it was only .7 amps with no load. Does anyone know if this is normal for these motors to run hot?

[Al_The_Man]

Some motors are TENV, Totally Enclosed Non Ventilated.
Nevertheless for some, the application they run in provides cooling, for example submerged pumps and large fans where the environment provides the cooling.
It all depends on the application the motor was built for.
Your motor would have to dissipate around 100w when running continuous on and off load so it is going to get warm.
I assume you have the right size start/run capacitor on it?
Al.

[Joe Weldor]

thanks Al The Man
I double checked the capacitor that was sent with the motor, it's marked 4uF 370V
60Hz. The diagram on the motor indicates a 5uF capacitor is to be used. Could this be the problem?

[Al_The_Man]

I wouldn't think it would make that much difference, If you have a 1uf AC rated cap around you could try it in parallel.
If it is a small motor, the cap IS most likely in circuit all the time, i.e. run cap, not just a start cap.
Al.