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Re: Induction motor start windings



Original poster: "J. B. Weazle McCreath by way of Terry Fritz <twftesla-at-qwest-dot-net>" <weazle-at-hurontel.on.ca>


At 06:48 PM 03/08/01 -0600, you wrote:
>Original poster: "Paul Arrowsmith 
>
>A while ago I pulled out the motor from my old washing machine (50Hz 240V in 
>Australia) and now wish to construct a SRSG with it, don't know the HP? but 
>it has a 3.5 inch diameter rotor.
>It has 3 windings one start and two others joined together
>The start winding is switched by a centrafugal switch but there is also an 
>extra single pole double throw switch attached to the centrifugal mechanism 
>that switches from one run winding during starting to another run winding 
>when spun up.
>When I power it up it draws lots of current, hums, and turns slowly if at 
>all.
>I did not find a capacitor when I salvaged it unless it was mounted out of 
>sight away from the motor. For now I am assuming that a start cap should be 
>in series with the start winding and this is the problem, is this correct?
>What's with the two run windings? I wonder if it has a different number of 
>poles for running and startup?
>Hope some one with more motor knowledge than I can help.
>Thank,
>Paul A
>

Hello Paul & coilers,

My father had a motor rewinding business years ago and I asked him
about your motor.  As it came originally from a washing machine, it
could very well be a two speed motor, slow for the wash cycle, and
fast for the spin/rinse cycle.  The slow speed would make use of
four poles, while the high speed would be two poles.

As to a starting cap, it may or may not have had one.  Generally if
a motor has a cap, it's mounted to the motor's exterior in a small
sheet metal can, and the leads pass through a grommet in the casing
to get inside to the centifugal switch and the start windings.

How many leads, excluding a ground, actually come out of the motor,
and are they identified in any way?  Here in Canada, there is a more
or less standard way of identifying the leads.  T1, T2, T3, and T4
are the run windings, with 1 & 2 being one winding, and 3 & 4 the
other.  For 120 Volts, 1 & 3 are joined and 2 & 4 are joined, while
for 240 Volts, 2 & 3 are joined.  A simple parallel or series hookup.
If it's a single voltage motor, only T1 and T4 will be used, whether
120 or 240 Volt.

The start windings are T5 and T8, but in reality only one of them
actually goes to the start winding directly, while the other goes
to the centifugal switch (and capacitor) before connecting to the
other end of the start winding. 

I hope I've not gotten you totally confused, but maybe your motor
will have a similarity that will help you suss it out.


73, Weazle, VE3EAR/VE3WZL

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
           or ve3ear-at-rac.ca
Web site:  www.hurontel.on.ca/~weazle