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Electric Motor Help NEEDED!!

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Groundhog

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#1
My air compressor quit working while I was using it (more specifically the electric motor quit). Don't know why. I was using an air tool and it just never came back on when the pressure got low. But it did get pretty hot (not smoking but hard to hold my hand on it).

It is a 3 HP, single phase 230V., 1740 RPM, 184T frame, "Farm Duty" Lesson. I bought this compressor used 3 years ago. No history on it.

First - I'm real stupid. I didn't actually test for voltage but . . .
1) the reset button was not popped out (but maybe felt like it doesn't have much range of movement).
2) the breaker did not trip.
3) The pressure switch is working and there is continuity through the switch
4) It gets hot as soon as I turn on the breaker.
5) I replaced the bearings about a year ago. It was remarkably clean inside then.
6) I just opened it up (expecting to see melted stuff) and it all looks clean and normal. No indications of heat. Capacitor looks good with no budges or discoloration.

Closest place that actually works on motors is 40 miles from here and I don't know their turn around time. Probably longer than I want to wait (I want it fixed now)!

Any ideas or things I should check (besides voltage to the motor) - which I will go do right now.

Thanks!!!
 
Last edited:

Groundhog

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#2
OK, I checked for voltage. The pressure switch is getting 240V. through it. In a few hours I will put the motor back together again and see if I can get it to "chooch".

(chooch is AvE speak for work or run). And if you haven't seen AvE videos you need to - he expertly tests tools and other stuff, but be prepared for some irreverence and profanity. https://www.youtube.com/user/arduinoversusevil/featured
 

tweinke

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#3
Stupid thought....... did the circuit breaker or fuse pop in the breaker box. Don't ask why I thought of this! :cower:
 

Karl_T

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#6
I'd pull the belt and replace the capacitor as the first trial. It just a common failure and cheap to try.
 

mksj

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#7
If you trace voltage or continuity to the motor, then the most likely failure is the capacitor. In many cases they will appear normal, but the motor may hum when power is applied and it will get hot. It may also be that the thermal overload switched popped and will not reset until it is cooled down. You can check each with a continuity meter. The capacitor can be checked for uF with a multimeter or you can use an ohm meter once the capacitor is discharged (normally not an issue with AC vs. DC).
 

den-den

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#8
In addition to verifying voltage and considering capacitor failure, make sure the shaft is not frozen/bearings locked up.
 

Groundhog

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#9
OK, think I found the culprit. Looks like the reset button is DOA. It stays open unless I wack it just right (yes, it is cold - just fubar). Pretty simple except they don't make them anymore AND if they did they are around $80! It is plastic and glued together so there is not much chance if taking it apart and fixing it (although i guess if I got desperate I might be able to make a new housing from derlin or something - if I can salvage the guts). Anyhow, I'll go to the electrical supply tomorrow. If they don't have a replacement I guess I still get to go the 40 miles to the motor shop. I need a nice drive - not.

Thanks for the advise!
 

killswitch505

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#10
Take a pic of it and what's the HP of the motor and the amp range of the overload? a lot of the time the supply house will give you cash or counter pricing if you talk to an actual salesman they can get you another 15-20% ask for the good price.
 

tq60

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#11
Is the reset button just the button or is it a thermal overload switch?

If it is just the actuator for something somewhere else than cut it open.

If it is actually the overload switch then you may need to look at other options depending on the motor.

There may be other off the shelf options too.

Motor protector is on

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 

markba633csi

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#12
I would just bypass the button if you can, replace it later (or never)
we don't need no stinkin' buttons:p
Mark
 

mksj

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#13
There are a number of option, the thermal overload buttons are very common, so something like below should work. You can check the current rating for the unit in your motor to see what it is rated. You can call Leeson or a motor distributor like Wholesale Electric Motors: http://www.electricmotorwholesale.com/
https://www.amazon.com/NTE-Electronics-R58-20A-Terminal-Resistance/dp/B002SR1WGY/ref=pd_sbs_60_5
http://www.ebay.com/itm/NTE-Electro...rcuit-Breaker-250-Quick-Connect-/381980491427
https://www.amazon.com/uxcell-Compressor-Circuit-Overload-Protector/dp/B00VG9N0RY/ref=sr_1_1

You could also just bypass the internal thermal overload and add a magnetic starter, the pressure switch tuns on/off the contactor and there is a thermal overload relay which is adjustable. I use this on my compressor, I added an additional ON/OFF switch which just disconnects the contactor coil power. This presents the unit from starting/running when I am not around, in case there is a line break.
 

Groundhog

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#14
I would just bypass the button if you can, replace it later (or never)
we don't need no stinkin' buttons:p
Mark
Sounds like my kind of solution. It's just one more thing to break anyway.
 

Groundhog

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#15
What I called a reset button is actually a "Phenolic Motor Protector". I'll look locally for a replacement tomorrow. All I need is a motor protector that will work with my motor's specs (which I have). If all else fails I found one at ESI $71 plus shipping. Sounds like a lot but I need my compressor.

I wouldn't have even posted this but I thought it was something more serious that I wasn't finding. So . . .
Thanks again for everyone's input.
 
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