Electric motor runs hot

[daBIGKAHUNA]

I have a 1/2hp - 3450rpm electric motor I am having issues with. Its and aerator motor for a septic system. It starts and runs fine but after about 5 minutes its fire hot and you can smell what appears to be plastic burning. I checked the capacitor and found a thick oil on the outside so I changed it out - still has the same issue. I googled it and the only thing I came up with for this problem is a stuck centrifugal switch and this motor has no centrifugal switch. I tore the motor down and there was what appeared to burned hard plastic in it but the windings are in tact and there doesnt appear to be any other damage. There is no thermal protection on this moter either.

Anyone have any idea what could be causing this problem? Trying to save the $300+ cost of a new motor. Any help would be greatly apprecieated. Thanks.

[Thorpe]

Ohm out your windings... Start winding and the run winding... What do the read vs. name plate? If you have melted down the plastic internally, I would imagine that you have a few shorted windings, and are running on borrowed time due to winding insulation likely burning off...

[Texaskev]

Motor needs rewind. Look it up locally, you should be able to find a repair shop that can rewind it for you.........

[daBIGKAHUNA]

Thanks for the advice guys - its about what I expected. I'll see if I can get it rewound.

[tri again]

Hi

Has it been in service a long time?
Odd that there's no thermal overload or cutout of some kind.
Perhaps it's supposed to have a short duty cycle so that extra stuff isn't necessary.

Neighbor (union electrician) replaced 2 motors in the last year at 400$ a crack.
Aggravated and everything else, he found that the pump motors almost never shut off.
He actually hooked a floodlight to it so he could see when it came on.

Not sure of the whole story, but something about float level or underground water leak
allowing surface water into the system so it would run constantly.

It'd be nice to save the 'new' pump from the same overheating.
I wonder if there's an aftermkt kill switch thermal overload safety something or other avail?

[Xpress]

Overheating electric motors generally comes from over amping it. That can also fry the windings and make it draw even more current, so yes get the motor checked out from a reputable repair shop, and double check that nothing is causing the components to bind up in any way from debris or something.

[daBIGKAHUNA]

Hi

Has it been in service a long time?
Odd that there's no thermal overload or cutout of some kind.
Perhaps it's supposed to have a short duty cycle so that extra stuff isn't necessary.

Neighbor (union electrician) replaced 2 motors in the last year at 400$ a crack.
Aggravated and everything else, he found that the pump motors almost never shut off.
He actually hooked a floodlight to it so he could see when it came on.

Not sure of the whole story, but something about float level or underground water leak
allowing surface water into the system so it would run constantly.

It'd be nice to save the 'new' pump from the same overheating.
I wonder if there's an aftermkt kill switch thermal overload safety something or other avail?


I havent been in country but apparently it was a fresh motor with less than a year of service on it. Also - this thing is supposed to be on a timer that cycles it and there is no timer to be found - that will have to be fixed and I agree - some sort of safety (external possibly?) would probably save some bucks down the road.

[daBIGKAHUNA]

Overheating electric motors generally comes from over amping it. That can also fry the windings and make it draw even more current, so yes get the motor checked out from a reputable repair shop, and double check that nothing is causing the components to bind up in any way from debris or something.

Another excellent point - I need to check the entire circuit from panel to pump.

[Dirtcrasher]

Guess what one of the largest culprits of over amping is?? Loose wires/corroded terminals. Seen it many times.

If it is a 3Phase motors all 3 legs should have the same ohms (disconnected) and all 3 legs, the same amps when running.............

3450 is an odd rpm versus the typical 1725. You could put fuses in the feeds, make sure the wires are the correct gauge... If it has a timer and motor starter smewhere, the heaters should be the correct size too (they act like fuses).