Re: SRSG motor anomoly

To: tesla-at-pupman-dot-com
Subject: Re: SRSG motor anomoly
From: "Jon Lagler" <rockcrawl-at-netzero-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 21 Mar 2000 17:24:31 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme


----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, March 21, 2000 9:55 AM
Subject: SRSG motor anomoly


> Original Poster: "Mark Broker" <broker-at-uwplatt.edu>
>
> Hey,
>
> I finished machining 4 flats into the armature of a 1725 RPM 1/4 HP (or
> something close) motor recently.  Today, I attached my G-LE rotor (no
> electrodes yet :-(  )  to the motor and fired it up.  Ran pretty smooth
> after balancing.  I grabbed an old stroboscope and clocked it at 1800RPM!
> I was happy, despite there being no way with this scope to test for rotor
> position vs. the AC cycle.
>
> Then, I applied a little load to the rotor by gently pressing on it with
my
> hand.  The rotor position rotated about 10 degrees, then a full 90 degrees
> (to the next pole).  It took surprisingly little pressure to cause this.
I
> was wondering if I need to grind a little more off the armature?  I
> machined 4 flats .675" across, which is the distance between the two
"dead"
> poles in the winding.  That is according to the directions I found on
> Terry's site.  Is it possible that the motor is crap?  It was replaced in
a
> furnace.
>
> Thanks
>
> Mark B.
>
Mark,
 I'm sure you can get a little more locking power by increasing the size of
the flats. As far as  know, the only drawback is increased heat, and maybe
higher current draw. I have a 1/2hp 1725 motor that runs synchronous with
only two flats. I beleive it works only because I made the flats WAY too
big. It doesn't get too hot for TC use. I also have a smaller 1725 motor (hp
unknown) that I modified with only two WIDE flats, and before I got to use
it on a rsg, I needed it for the exhaust blower on my sandblasting booth. It
ran for about 30 minutes before it overheated and locked up.
 So it seems like you can go wider to get more phase locking, but if you go
too wide it'll overheat. Good luck!

Jon Lagler

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