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Would this wiring mistake have blown a motor?

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Question: Would this mistake have blown a motor?
I was given a 230/460 motor that was used – but supposedly good. To test it, I temporarily wired it to my lathe VFD today. Access and visibility inside the panel was limited and I stupidly had gotten two of the motor feed wire under the same connector. So the L1 motor lead was connected to the L1 terminal, The L2 terminal was empty and L2 and L3 leads were attached to theVFD’s L3 terminal. I also ran a ground from the motor frame to the panel .
I started the VFD with the Potentiometer at zero and slowly increased. The motor bucked a few times and a small arcing occurred at the ground. I then rechecked the wiring and corrected my mistake.
Trying again I set the pot to zero, flipped the run switch and the motor would ramp up about one fourth of the way then it would trip out the VFD. I reset the VFD and got the same results on the second try. I do not remember the error code.

I am not knowledgeable on electrical and just don’t have a feel for it. Do you think my wiring mistake would have damaged the motor… or was the motor probably bad to start?
The VFD runs fine reconnected with my lathe.
The VFD is 2HP, the motor is 1.5 HP.
There is no smell on the motor as though it had burnt.
I do not have a feel for electrical and would like the opinion of someone with electrical knowledge of three phase motors.
Thanks
Jim
 

Comments

#2
ohm the windings, start there
 
#3
I doubt you damaged the motor, you probably need to change some settings in the VFD to match that particular motor, OR the motor was/is already bad
Do you have a motor shop nearby that can test the motor? There may be a bad winding but you need a sensitive ohmmeter to check that
You might try hooking up the motor again and record the error code- it may put you on the right track- use the VFD itself to help troubleshoot the problem, those things are pretty smart
mark
 
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#4
Did you confirm that the motor is wired for 230 volts? If its wired for 460, it won't hurt the motor, but it will try to draw double the amps and trip the VFD.

BtoVin has a good suggestion. "Ran when parked" is something we hear a lot in motorcycles. Doesn't mean they run now.
 
#5
I agree with the others, I don't think you would have damaged the motor connecting it incorrectly, I would have been worried more about the VFD. But VFDs are pretty smart and will protect themselves so I would guess no damage there.

Check the motor connections in the box. Should be U or T1 to 1-7, V or T2 to 2-8, W or T3 to 3-9, and 4,5,6 connected together for 230 Volts. It very well could be that the motor has a shorted winding, the sparks on the ground wire is a good indication of something is not right.
 
#6
Thanks guys for the quick response. In response to the suggestions I did have the motor wired for 230 V. The error code that showed was OCS "Over Current at Start", I did not attempt changing the VFD settings - since the motor specs were close to that of the lathe motor and it runs well. So I jumped to the conclusion the motor was bad - and did not want to harm the VFD.
I didn't elaborate on the situation. It was a friends motor. He believed the motor to be good - bit did not know for certain. I took it to test with the VFD to be sure it worked before I offered any payment. Since there was no smoke or smell I didn't think the incorrect wiring as I mentioned would have damaged it. I returned the motor to him and told him it didnt work and he was good with that.
Afterward I started second guessing myself and wondering if my actions could have caused the motor to burn up.
If so - I feel I ought to compensate my friend.

Thanks guys.
Jim
 
#7
If the motor was wired for the correct voltage up front, it likely didn't damage itself over a spark. What it was doing would be called "single phasing". If it had been damaged there, the majic smoke would have gotten out and it would have smelled burnt. Single phasing for a short period, 30 seconds or so, probably didn't hurt it. Ring it out to the frame with an ohm-meter up front. It should be very high resistance, phase to ground. Just enough meter movement to prove the connection.

BTW, a three phase motor will sorta run on single phase power. But it won't start. That is how "rotary converters" work, with a capacitor as a "kicker" to get it started and another to offset the running.

If your VFD is working on your machine after the test, I would look to the motor. Electrical equipment runs off majic smoke. If you let that smoke out, it doesn't work any more. And the smoke is very difficult to put back in. It requires a specialty shop setup to do it.
 
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