Re: [CAD_CAM_EDM_DRO] Strange motor - question

Jon Elson wrote:

> How did you determine it was 24 poles? Did you just count stator
> slots? Those are not the poles, but just slots to put coils into.

Actually I counted the higher bare parts between the slots (same
thing though) and found 24. Didn't look at the way the slots were
filled at all. Now that I have, I can see that the motor is not 24
pole but probably 2 pole.

> What is 3s50? Do you mean 3450 RPM? That would indicate
> a 2 pole motor. But, even if it WAS a 24-pole motor, as long as it
> was 230 V, 60 Hz, the VFD should run it fine.

The s in the 3s50 is "something I can't read" and I would guess it's
a 4, but don't know.

I did some more testing and now think it is probably not a 230v
motor. I made an assumption since I've never come across a 3 phase
motor that runs on 120, but that is probably what it is. Using a
Variac and starting the motor by hand, It will run on 40 vac quite
nicely, but without having the 3 phase there, begins to rattle at
about 65 vac. Higher voltage gives more rpm too. It will do this
on any pair of the 3 input wires showing that the motor is OK. But
at 120 vac, it won't run on my Hitachi SJ100 which faults, since it
only puts out 200-240 volts. I think that is understandable now.

> If it has an ordinary squirrel cage rotor, that sounds like a standard
> induction motor. An induction AC servo motor should run fine on
> a VFD, assuming voltage and frequency are compatible.

The rotor appears to be a solid block of metal. I am assuming it is
an ordinary motor, but the rotor is only about 2" OD and has some
aluminum ends closely fitted to the metal armature (iron or rare
earth?) so I can't see the construction.

Anyway, Jon, thanks for the comments which pushed me into a few more
tests. If I can find a source of 3 phase 120 vac, I'll have the
problem nearly solved. This is what happens when I visit surplus
places....then make some standard assumptions based on partial
knowledge.

JerryK