Repulsion Induction motor

I've got a ~ 50 year old Wagner 5 hp repulsion induction motor that's
been sitting around forever. I decided to put it on a air compressor
I picked up that had a 3 phase 5hp. Supposedly, the motor had been
rebuilt before it sat in storage the last 40 years, and it does in
fact look fairly clean inside and has good starting brushes. I think
it came off a refrigeration unit. Weighs about 200 lbs.
Anyway it sparked on the commutator a fair amount on the first
start, and once in a while during starting it seems to go into
induction mode but then drop back into repulsion mode a few times
before finally staying in induction mode. Current draw is as per name
plate, ie 30 amps at 230V when up to speed and it runs cool. I took
it apart, turned the commutator and undercut the mica. When I
reassembled it still had the same problem. While apart I was
wondering if perhaps shorting keys were in backwards, these are about
100 thin copper plates about 1/4 x 1" long held in a circle by a wire
ring. I put them back in the way I found them. They get pushed
rearward into a shorting position when the flyweights push back two
pushrods that run lengthwise thru the armature. The pushrods also
lift the brush assembly from the commutator when the motor reaches
speed. Can't really see anything wrong...Anyone ever see one of these
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I've got a one hp repulsion induction motor on a compressor and that occasionally sparks on starting, especially if it can't kick the compressor over which happens from time to time. If that happens it's just a matter of turning it off and on again and it always seems to kick it over then and all is fine. The compressor has an unloader so once running it doesn't stop turning. One thing I found is that you can alter the direction of starting and also how much torque it generates by the position of the brush ring. This motor has a clamp which can be loosened and the brushes rotated.
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David Billington
I loved those old repulsion induction motors. I've had them on compressors and machine tools. When overloaded they just slow down but do not draw excessive current. Make sure the ring of shorting keys (called the necklace) have clean and smooth contact surfaces. , both on themselves and their mating surfaces.
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You need a slightly smaller pulley on the motor - it is overloaded on startup.
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I cleaned the necklace with a Scotchbrite fine wheel, it's contact faces were a little pitted. I also Scotchbrited the ID of the commutator it rides on. I'm wondering if the "necklace" is in backwards, since the motor was never run much after being rebuilt 40 years ago. I "borrowed" off a 12" jointer that used to belong to my dad, he only used it a few times on the jointer. The other odd thing is that it starts better with the brush holder reverseing ring adjusted closer to the neutral point, than on the mark. I don't think the compressor was overloading the motor on start as it was only pulling a peak of around 40 amps on start and the unloader is working. It occurs both when the compressor has a empty or full tank when starting. Also about 50% of the time it starts fine. In any case it's going back on the jointer now, I just put a new 5hp Baldor on the compressor. Pretty good deal actually, $380 for a brand new Baldor 5hp 1ph. 1750 RPM motor on Ebay and fast shipping. Looks like the guy has a bunch of them both new and takeoff's. More like $600+ from Grainger.
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