O/T sort of eletic motor problems

old · Jun 5, 2008

I have a 1/2 hp motor on a small hammer mill. Well it will spin up then stop and then spin up again. It never spins up like it should and may run 30 seconds or so stop then spin up again and stop over and over again. Also if you touch it when its spinning up it will zap you. What the heck is wrong with it. This is an induction start type not a cap. start type.
Thanks
Hobby farm

buickanddeere · Jun 5, 2008

Has this motor/mill worked fine in the past and suddenly developed the problem?
Is the mill supllied from a two prong extension cord?
If the motor is supplied from a three wire cable there is something very very wrong with the electrical service/system/circuit/plug/motor grounding.
Is there a thermal overload button the motor somewhere?
1/2 HP seems very small for a mill motor.
120 or 240V?

Janicholson · Jun 5, 2008

It is shorted inside, pull it apart (unplugged)JimN

John T · Jun 5, 2008

Rich, Ima thinkin theres a short from a winding to the case and I dont like the sound of that. Maybe try an ohm meter test from the plug or whatever motor input wires and theres shouldnt be any continuity from those wires to the motor case or else theres a short. The start winding ought to get it going and then a centrifugal switch opens and it drops out leaving the run winding(s). Also if the motor is served by a good n correct wired 3 wire grounding circuit/receptacle/plug etc., the grounding conductor (bare or green) should get bonded to the motors case which provides a dedicated low impedance current path back to the panel to trip the circuit breaker in case a winding gets shorted to the case.

Id check for a winding shorted to case n then get that circuit wired correct cuz the motors case should be grounded.

John T

old · Jun 5, 2008

This hammer mill is small as in less then a foot square. Yes it has worked just fine in the past but with the high rains here I think it got under water once maybe more

souNdguy · Jun 5, 2008

I had an old grinder that did that.. was a short to the case.. and was a 2 prong setup... I junked it.....

soundguy

Paul from MI · Jun 6, 2008

Unless it is something shorting out because of miosture, I'd just replace the motor. You can't afford to do much to a small motor like thgat. They are just abou throw-away items. If it's been on a hammermill it may have quite a bit of dust inside that will hold moisture. Could try taking it apart and cleaning & drying it first.
Good luck,
Paul

Kentb of SWMO · Jun 6, 2008

Not a short. Sounds like the RUN winding is open. I have had one like this. turn it on and the start winding would spin-up the motor until the start switch opened. Then the motor would wind down until the start switch close and the motor would spin-up again in a repeating cycle.You will need to replace the motor.

Kent

old · Jun 6, 2008

When you first turn it on it will spin up like it should and run just fine for 30 second or a minute then it starts the stop start thing and does that till I turn it back off

Kentb of SWMO · Jun 6, 2008

Like I said the motor is ONLY running with the start winding. The start winding will spin the rotor up until the start switch is opened by the centrifugal control of the switch. Then the rotor will coast down until the start switch closes again and spin it up again. If the motor does not have a load on it, this cycle could be a fairly long cycle. If you put a load on the motor the cycling will be shorter. I had one on my lathe do this.

Kent

O/T sort of eletic motor problems

old

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buickanddeere

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Janicholson

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John T

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old

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souNdguy

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Paul from MI

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Kentb of SWMO

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old

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Kentb of SWMO

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