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Old January 31st 21, 09:29 PM posted to rec.crafts.metalworking
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Default Motor question

I don't think your motor is wired in shunt configuration unless it is
REALLY old, like maybe 1890s old. Shunt wired motors are used in DC
applications but not AC, which is what a universal motor can run on.
Is there any way you could send me some pictures of the thing?
Including the label and commutator? I suspect the brushes may actually
be wired together.
Eric

On Fri, 22 Jan 2021 19:52:12 -0600, Snag wrote:

It's an old motor , 3/4 hp . And it's a universal motor , with a flat
disc commutator and brushes that can be rotated to reverse motor
rotation . I was looking at it today and saw on the tag that it can be
operated on 110 or 220 volts ... Currently it's wired with the armature
and field windings in parallel , I believe that's called shunt . I was
operating it on 110 volts on my lathe (until I got a smaller unit , this
thing is huge) . I have a project that I might use it on , but I'd like
to go 220V . Am I correct in assuming that hooking the windings in
series will convert it to 220 ? Since this motor is a universal motor ,
is it speed controllable by varying the voltage ?



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Old January 31st 21, 10:46 PM posted to rec.crafts.metalworking
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Default Motor question

On Sat, 30 Jan 2021 22:56:43 -0600, Snag wrote:

On 1/29/2021 3:31 PM, David Billington wrote:
On 23/01/2021 14:31, David Billington wrote:
On 23/01/2021 01:52, Snag wrote:
* It's an old motor , 3/4 hp . And it's a universal motor , with a
flat disc commutator and brushes that can be rotated to reverse motor
rotation . I was looking at it today and saw on the tag that it can
be operated on 110 or 220 volts ... Currently it's wired with the
armature and field windings in parallel , I believe that's called
shunt . I was operating it on 110 volts on my lathe (until I got a
smaller unit , this thing is huge) . I have a project that I might
use it on , but I'd like to go 220V . Am I correct in assuming that
hooking the windings in series will convert it to 220 ? Since this
motor is a universal motor , is it speed controllable by varying the
voltage ?

It may not be a universal motor but rather an repulsion motor
https://en.wikipedia.org/wiki/Repulsion_motor , possibly a repulsion
start induction run variant. I have a 1hp one on a compressor and the
commutator segments move once up to speed to take them out of the
circuit and like yours the brush position can be changed to alter the
starting torque and direction.

If this is a repulsion motor then there is no connection of the brushes
to the mains they simply serve to short the rotor. That would seem to
leave the need for 2 field windings for dual voltage operation them
being wired in parallel for 110V operation and in series for 220V. In my
repulsion start induction run motor the action of the commutator segment
moving when the motor runs up to speed is quite obvious with the brush
access cover removed. Access to some images would help to comment further.


You may be right , I'll have to check it out and see if the
commutator pulls back or , more likely , the brush assembly pulls away
from it . I used this monster for a short time on my Logan/PowrKraft
lathe , but never paid much attention to what was going on inside the
end bell .

I'd bet on it being an old repilsion start induction motor. Any tag
on it? Is it a Leyland or a Century by chance? Have you put a tach on
it?


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