RE: better sync motor mods?

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

Original poster: "Basura, Brian by way of Terry Fritz <twftesla-at-uswest-dot-net>" <brian.basura-at-unistudios-dot-com>

John/all,

I've modified a dozen plus motors and have never needed to cut all the way
through any of the current bars (BTW - Is current bars the correct term?).

I use the dead pole method to determine the max width of the flat for a
particular size and type of motor. Then I slowly work towards this maximum
a little at a time. Each time I remove metal I reassemble the motor then
measure and document minimum sync voltage and current with a mechanical
load applied. This process has produced solid salient pole synchronous
motors with an average increase in current of only 12%, no noticeable
heating, and plenty of torque.

Note-I use only 1/3 or 1/2hp motors so a slight reduction in torque would
be hard to detect without proper test equipment (A dynamometer to test and
document electric motors is one of the hundreds of projects on my to-do list).

Side note - I have some of Tesla's writings on synchronous motors. I'll see
if I can find them tonight or tomorrow. It may shed some more light on the
subject since he did invent synchronous motors  :)

Regards,
Brian B.

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Wednesday, January 10, 2001 7:07 AM
To:	tesla-at-pupman-dot-com
Subject:	Re: better sync motor mods?

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<FutureT-at-aol-dot-com>

In a message dated 1/9/01 9:16:24 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> Hi John,
>  
>  I had a thought along the same lines a while back. This was probably in May
>  of last year, anyway just before I built my second sync rotary. I had
>  thought that rather than cutting a flat, why not mill a groove in the rotor
>  that is deep enough to cause the magnetic field which is induced in it to 
be
>  separated into "poles" without removing so much material as to cause the
>  current to increase as much as it would with the flats. I also thought that
>  the torque might not be diminished as much. I tried this on one motor, but
>  it would not lock in sync. once I had turned the grooves into flats of the
>  same depth, it worked as expected. I don't know if it would have worked if 
I
>  had made the grooves deeper. As far as cutting the current bars goes, it
>  seems to me that some have to be cut to get the thing to sync. I had
>  wondered if this might not be more the mechanism than the iron removal.
>  
>  later
>  deano

Deano,

Thanks for that report.
Whenever I've modified motors, I've never had to cut all the way
through the current bars.  But it sounds as though you have?
How wide were the grooves you cut, relative to the uncut
portions?

John Freau