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Motor wired for 220? ? Plugged into 110

AKAvMech

Plastic
Joined
Nov 5, 2023
I recently started a job at a site that has an old lathe sitting in the hangar. It has been retro fitted with a GE KC series motor (series wound / capacitor start). It also has a drum reversing switch on it. There is 110 wiring going to the drum switch.
What I heard from the mechanics that have been there for a while is that the motor is 110 only, and it pops the breaker when you try to run it. I didn't think to ask if it pops right away or if there is a delay.
My internet research shows the motor to be dual voltage. I checked the windings, I got 2.0 ohms across one pair of leads, .6 ohms across another pair, and .2 ohms across the last pair. I was checking from the drum switch. I found no shorts between windings, I didn't think to check from the windings to the case. That was as far as I got before my rotation ended. Hopefully I will have time continue next rotation.
I'm not on site now, I'll be back there on the 15th.
I'm wondering if the motor could be wired for 220.
Could a motor wired for 220, and plugged into 110 just pop a breaker?
If the motor was wired for 110, would you expect wires to be ganged together either at the connection box or the switch?
I'm trying to educate myself, but I know very little about AC.
 

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Yes, it can pop the breaker, I have a 2hp 120/240 single phase motor on my air compressor. Very handy single toggle switch on the motor box to switch between the two. It will sort of work at half the voltage it needs but will trip the breaker before it gets to maybe 60psi.

120 into a 240v motor will work on a small lathe or bench grinder, if it gets up to speed. (An air compressor wont). If you overload it and the motor bogs down, the breaker will trip or the motor will burn up.

That does look like a 120 only motor. The 0.2 ohms is the start switch, 2 ohm coil is the main run winding, .6 ohm coil is the capacitor start coil.

120/240v motors will have 2 equal windings.
 
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Thanks for the reply. I guess I will start looking into the possibility that the motor is bad.
 
Does the motor spin freely? Does the capacitor read the appropriate value?

If you give it a spin then apply power, does it start?
 
Thanks for the reply.
I don't recall if I checked to see if the motor spun freely or not. Nor did I think to check the capacitor until after I left. Those are a couple of things I plan to check when I get back on site, and have time. I also plan to check the amperage rating of the breaker it's hooked up to, and whether there is anything else drawing current on that circuit. Giving the motor a spin and then applying power sounds like a good thing to try as well. It's a belt drive, and I took the belt off to tilt the motor. Trying to run the motor with no load would probably be a good test. I also plan to spin the pulley on the lathe to see how that feels.
I am just getting started on this, and I have been getting historical information in bits as I get a chance to talk to mechanics on the other rotation. i didn't try to start the motor myself. So far I have been trying to gather information and not getting to deep into it. Also, I thought there might be someone else on the other rotation working on it, and I didn't want to step on any toes. I now know that I am the only one trying to get it going.
 
In case anyone is interested, I found a few minutes to play with the lathe. I found out that the motor will run for a short time, then pop the breaker. The capacitor also let some magic smoke out. I did some internet searching, it seems that is an excellent indication that the centrifugal switch is not opening. It looks like we may get a break from aircraft inspections soon, if that comes true I might take apart the motor and look at the switch.
 
Every one should own --and use--- a Megger ...........anyhoo,yes the cap could be bad ....a new one is about $30 ......also beware a stuck centrifugal switch ,this will burn up a good motor ......IMHO,smell is good indicator of dud windings ,and also brown or black discolouration.
 
Update. I disassembled the motor, cleaned it, lubed it, and repaired the centrifugal switch that was stuck. The motor now works.
Thanks to everyone for their help!
Brett
 
Update. I disassembled the motor, cleaned it, lubed it, and repaired the centrifugal switch that was stuck. The motor now works.
Thanks to everyone for their help!
Brett
You should change the start cap. Once you have let some smoke out, you have degraded the cap and likely to fail. When they do, many times they short and can take out the start winding in the motor. Ask me how I know. We got in the habit of installing a secondary fuse on the start circuit. Not common but it can save an expensive motor.
 
You should change the start cap. Once you have let some smoke out, you have degraded the cap and likely to fail. When they do, many times they short and can take out the start winding in the motor. Ask me how I know. We got in the habit of installing a secondary fuse on the start circuit. Not common but it can save an expensive motor.
Thanks for the tip. I requested a new cap, it is supposed to be purchased and sent to the site. I will send an email to the guys that are there now, and suggest not using the lathe until the new cap is installed.
I used the lathe some while I was out there, occasionally the motor would "growl" on start up. Once I let it run and it popped the breaker, all of the other times I just stopped and restarted it, and it ran fine. I'm hoping that a new cap will cure that.
 








 
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