Motor Repair/Replacement questions

Mike Gesualdo

Mike Gesualdo

Joined
Nov 11, 2012
Messages
220
Hey all,

So the approximately 10 month old electric motor on my grinder (Esteem 2x72) started acting funky the other day, cutting out at high speeds then sputtered out soon after. From the error LEDs on my VFD and a short conversation with the folks at KB electrics, they diagnosed it as a short in the motor. I've been stuck with hand tools for the past couple of days... and while it's been fun, I want to get my grinder operational again :)

I'll admit to being a complete newbie when it comes to all things electric motors, and while I spent a few hours the last few days educating myself on the subject... I figured I'd consult you guys before running off and doing something stupid.

The culprit is an Elektrimax 3ph 1.5HP 1800RPM 56C motor, hooked up through with a KBAC-27D VFD, running at 120V. I'm potentially covered under the warranty period for the motor, however Toolmex was unwilling to help without some sort of proof of purchase, and I haven't been able to get a hold of Brett (who built the grinder) yet to acquire that information.

I guess my first questions is... could a repair be simple enough to repair on my own, only armed with Google? And if not, would it be financially viable to take it to a professional? I'd hate to kill a salvageable motor with my lack of expertise, but I'd also hate to spend more than the cost of the motor getting it fixed :P

In the meantime, I plan on purchasing a new motor so I'm not out of service for too much longer. I figure if I do get the old one working, I'd find some other use for it eventually. From what I gather, I want something that is 1.5HP with my KBAC-27D running on 120V... and it should be NEMA/TEFC/56C frame, and the lower of the two RPMs (I'd love to bump up to 240V, but unfortunately it's not an option at this point). I was looking at this particular Leeson 3ph 1.5HP 1740RPM motor.

Would that work for me, or would something else be a little more ideal with my setup? Cost isn't too much of an issue to a point if a different model/brand would be a little more reliable.

Thanks!
Mike
 
Look in the yellow pages of Chicago for electric motor repair/rebuilding, It might say starter repair also, they can fix your problem. Industrial truck (forklifts)starters get hundreds of starter engagements daily and as a result need repair or replacement fairly frequently. Not a major expense. The ad at the top of this page is an excellent example of zactly what you need.:thumbup: well it was up at the top of the page I don't know what happened.
 
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Hey Mike grab a ohm meter and follow the directions in this link.
http://www.pcbheaven.com/userpages/check_the_windings_of_a_3phase_ac_motor/
There's not really any way of knowing for sure if the motor is bad until you check the windings. If you have a electrician buddy that has a megger that'll work too. If it was me and the motor was bad I would just get a new one. Actually I'm not even sure if you can get a motor that small rewound due to the burnout process it takes to strip the windings. Most of the time companies limit rewinding to 75hp and above.
 
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You can rewind almost any motor, the question is "is it worth the time and effort?" not to mention the cost of supplies! I used to wind DC motors for medical hand tools and let me tell you, it's a P.I.T.A! With a larger AC motor things get more complicated and are harder to work with. I'd recommend just buying a new one, or paying someone to fix the one you have... DIY-ing it will just lead to heartache... unless you just want to tinker... then I say go for it!
 
I'd remove power from it and open it up. Sometimes it is as stupid simple as a wire came out of a wire nut and is arcing to the frame and can simply be put back into the wire nut.

If you're getting a new motor and you're running it on a VFD make sure you're getting one rated for inverter duty. Preferably with a decent speed range.

I got this Leeson motor for my KMG : http://www.surpluscenter.com/Electr...230-460-VAC-3PH-145T-LEESON-MOTOR-10-2723.axd

Not a bad price for a cast iron frame, 10:1 speed range inverter rated motor.

They have one pretty similar to that enclosed motor you're looking at too : http://www.surpluscenter.com/Electr...-230-460-VAC-3PH-56C-LEESON-MOTOR-10-2719.axd
 
Just make sure the new motor you buy is three phase because single phase will not work with your VFD. Aside from that a motor that size is very seldom worth rebuilding when you look at the cost.
 
mattd88 said:
Hey Mike grab a ohm meter and follow the directions in this link.
http://www.pcbheaven.com/userpages/check_the_windings_of_a_3phase_ac_motor/
There's not really any way of knowing for sure if the motor is bad until you check the windings. If you have a electrician buddy that has a megger that'll work too. If it was me and the motor was bad I would just get a new one. Actually I'm not even sure if you can get a motor that small rewound due to the burnout process it takes to strip the windings. Most of the time companies limit rewinding to 75hp and above.
Click to expand...

That's exactly what I was looking for, and a lot more clearly put than other sites I came across... thanks! I don't think I'll be attempting to re-wind the motor myself, but I'll at least feel a little more comfortable knowing what's going on.

Going to go ahead and order a new motor... before I go off spending $200 on the wrong thing, would this one fit what I'm looking for running off of the KBAC-27D at 120V? Or should I drop down to a 1HP or different RPM?
 
Nathan the Machinist said:
I'd remove power from it and open it up. Sometimes it is as stupid simple as a wire came out of a wire nut and is arcing to the frame and can simply be put back into the wire nut.

If you're getting a new motor and you're running it on a VFD make sure you're getting one rated for inverter duty. Preferably with a decent speed range.

I got this Leeson motor for my KMG : http://www.surpluscenter.com/Electr...230-460-VAC-3PH-145T-LEESON-MOTOR-10-2723.axd

Not a bad price for a cast iron frame, 10:1 speed range inverter rated motor.

They have one pretty similar to that enclosed motor you're looking at too : http://www.surpluscenter.com/Electr...-230-460-VAC-3PH-56C-LEESON-MOTOR-10-2719.axd
Click to expand...

Thanks Nathan, I'll give that a shot. Would definitely be nice if it were something that simple :P

Looks like that second motor may be the same model as the one I'm looking at based on the catalog number... but they sure don't look the same, haha. I'll probably pick one up from your link in that case, as it at least lists it being inverter rated and it's a bit cheaper. I definitely need something in a face mount, as my grinder is a direct drive with the motor bolted directly to the frame. I'm not as talented as some of you folks are at rigging stuff up, so I'd prefer being able to just bolt it in :)
 
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