RE: better sync motor mods?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi John,

Actually when I was done the flat was deeper than the slot had been. No
evidence of there ever having been a slot. The fact of the matter is that at
the time I was not willing to take a chance on ruining that motor. Out of
twenty odd motors lying around that is one of only three 3450 RPM, and the
only A.O Smith, which until I took it apart, I had no Idea how nice it was.
So I ended up making the flats because I "knew" it would work, and was not
sure about the slot, and did not know what might happen if I kept going with
the slot, if I might ruin the motor if I got it too deep. If I had made the
slot deeper, who knows, it might have worked.

deano

> >  snip
> >  I have not tried your phase shift trick on this motor yet, but
> am planning
> >  to soon. I am guessing that the optimal cap value will be 1/4  of that
> >  required for a motor running on 120V. I am also giving thought
> to combining
> >  the method, as I have a couple of extra variacs. One to adjust
> the voltage,
> >  the other to shift the phase. Do you have any thoughts on that?
> >
> >  deano
>
> Deano,
>
> Well that was an interesting test you did.  So a 1/4" wide groove or
> slot was not wide enough for your motor.  I guess when you
> changed it to a flat, the slot was still there in the middle of the
> flat, since the slot was pretty deep?  Anyway, I just did a somewhat
> similar test which I'll post now, but I seem to be seeing different
> results (maybe), although my test was different.
>
> I agree that the 1/4 size cap seems to be correct.
>
> My guess is that using an extra variac to control the voltage will not
> extend the phase shift range over just one variac.  That's an intuitive
> guess on my part.
>
> Thanks,
> John Freau
>
>
>