About 15 Years ago I bought an induction motor from a junk yard. It have 6 leads being that 2 are the same lead, so 5.
The guy who sold me had no idea from what machine it came. And I don't quite remember what I did to make it work, I was 10 yo, maybe I just tried at random. But it had a very good torque for its size (about 8 cm in diameter and 12 cm long) and rotated about 800-1100 rpm, probably the strongest motor I have. It worked using a single running capacitor.
But I always noted it heated to much, and specifically one of the sides of it. I disassembled it, analysed the windings and also measured the DC resistance between the windings to check how it was. And what I've seen doesn't seem familiar. This is how it is:
I hope the image isn't confusing. Windings 1 and 2 are in series internally, as well as windings 3,4,5 and 6. But there was, according to my measurements, a 15 ohm fault between the white wire and the black wire. Being there is no physical connection between them.
Windings 1,2,3 and 4 are about 20-22 ohm in DC resistance each, while the windings 5 and 6 the double of that.
The way it was working was by connecting one phase to Yellow + Gray, a 45 uF capacitor from that phase to the white wire, and the other phase to the black wire.
Now, that only worked because of the said fault. Otherwise only the windings 1 and 2 would be energized. But the fault, which I found to be in the middle of winding 5, made winding 3 and 4 get energized, but also being greatly bypassed by the capacitor (which is in parallel with 3 and 4) and causing that segment of winding 5 to get extremely hot.
However, it still caused the motor to work well, and the greatest the capacitance the greatest the torque. Also made winding 5 heat like hell.
I don't quite understand why the rotation was low yet, because it still behave mostly as a single pole motor in that context. I think all of that conferred a strange torque curve to it.
But recently the winding 5 took on fire, and with that the said fault had a great increase in resistance. The motor stopped working.
For what I've seen, there's no need to restore this winding, but neither will it behave the same again if I actually wire it as a single pole motor with two auxiliary windings. It will now rotate at 3600 RPM.
So, instead, I want to restore it to it's full glory, in the way I can get the greatest efficency out of it. But I don't know how it's supposed to be used. And that's my question:
How is this motor supposed to be used?
I have never found any schematic for a motor like this one, and I don't know how it's supposed to work.