[BobM]

Hi,
I acquired a 1.1kW 415V 3phase induction motor at auction that I intend to use as a spindle motor (under control of a VFD) for an CNC'd X3 mill. I wired the motor up to the 3 phase supply to test. On powering up it seemed to run fine but after 60 seconds or so I noticed it was getting very hot and beginning to smoke. I turned it off immediately of course. I then realized the motor was wired delta. It should have been wired star for 415V. My mistake for not checking. Doh! Anyway, it got pretty hot before it cooled off as the heat came out of the windings into the frame. After it cooled I checked the windings with a multimeter and all are equal. They check out fine with a megger as well. Hooked up in star and ran again - all seems OK and it runs cool.

Is it likely that any significant damage was done to the windings that will cause problems down the track?

Thanks
Bob

[Al_The_Man]

It depends on if there was any insulation damage done when it cooked, after a major overheat, the insulation can become burnt and brittle, and gradually flake off, on subsequent heating and cooling cycles it is sometimes happens that as the copper expands and contracts a short between winding can occur.
Just depends on how far it went and how lucky you are!
Time will tell
Al.