Re: Microwave oven fan motors

["sundog" <sundog-at-timeship-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi all,

 I suppose that depends on your idea of *tiny*.  I use 4" PVC discs
cut with a hole saw for my SRSG.  It's a little .35A motor (pulls
~.5A hunting), and it hums along without a hitch.  Sure, PVC is bad
to use, but I pushed 2kva across it for a good 20-30 sec (lost a
tranny on that run), with no hitch, other than smoke rolling off of
the stationary electrodes.  The SRSG is a little tiny 1800 RPM
motor modified for sync operation.  With the 4" rotor, it work
beautiful on the little 2" form I use, and on the 4" coil at 2kva.
For much more current, I'd go to a bigger rotor (and naturally
motor), but to date, the rotor (maybe 1/2 hour total runtime) has
only yellowed a bit from the heat and UV (more UV than anything),
and shows no signs of being ready to fail.  I must admit, it eats
stationary electrodes like candy, they must be getting too hot, but
otherwise performs flawlessly.  I just assembled an 8 electrode
disc last weekend (am currently using 4), so I'll see how it runs.

 Sizewise, these things are tiny.  But hey, it works great for
small coils (and 2kva for that matter!).  I *do* strongly recommend
using a sync motor on a NST, as an a-sync will probably toast it in
short order.

So, Sundog's moral of the story, if it looks useful, it probably
isn't, but keep it anyway ;)

Sundog
-----Original Message-----
From: Tesla list <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Wednesday, August 30, 2000 9:36 PM
Subject: Re: Microwave oven fan motors


>Original poster: "Ed Phillips" <evp-at-pacbell-dot-net>
>
>> Induction motors do suffer slip and their speed is roughly
>> proportional to Fmains and inversely proportional to the
>> number of poles.
>>     Shaded pole motors are non-synchronous right frmo the word
>> go. The shorting copper bands are a cheap way of simulating a
>> start/run winding. They are terribly inefficient compared with
>> a good induction motor.
>
> Is this subject worth the discussion.  Those fan motors are tiny
and
>probably incapable of driving any decent-sized rotor.
>
>Ed
>
>
>
>