600V 3-phase motor (milling machine) --> 240V operation

Thanks for the advice.

Yes 600V definitely needs to be treated with respect, I recall from an electrical safety course (many years ago), that this is the most common voltage responsible for serious accidents and fatalities.

I have a few pictures of the motor.

Milling Machine 3.jpg

Milling Machine 5.jpg

Milling Machine 6.jpg
 
Making progress........

Managed to get the mill home in my wife's mini-van, disassembled it into three pieces. Loading was easy, four "He-man" at the pick up location man handled it into the van , and then I pulled it up and out the side door with a chain lift. Then built a rolling base to get it to its new home location. I'm not sure how much it weighs but must be in the ballpark of 450-500lbs. I have a used 1.5HP, "Inverter Duty" 240V, 3-phase motor with the same frame size as the original on order. I also picked up a used but supposedly good Altivar 31 VFD which is now wired (less the motor side).

I would like to perform a preliminary function test of the VFD, test: forward, reverse, speed etc. If I were to try powering the original 600V motor (no load) with the 240V, VFD do you think it will spin with the reduced voltage?
 
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Making progress........I would like to perform a preliminary function test of the VFD, test: forward, reverse, speed etc. If I were to try powering the original 600V motor (no load) with the 240V, VFD do you think it will spin with the reduced voltage?
Nope! Got to have the same voltage from the VFD to the motor. You more than likely will fry the VFD trying. Ken
 
I've tested VFDs without frying them by putting three lots of 240V bulbs across the motor terminals, keep adding bulbs for more load...

Hard to tell whether it's in forward or reverse, or what the speed is though ;)

Dave H. (the other one)
 
I would like to perform a preliminary function test of the VFD, test: forward, reverse, speed etc. If I were to try powering the original 600V motor (no load) with the 240V, VFD do you think it will spin with the reduced voltage?

It won't hurt the motor. It is very common for service shops to no-load test motors at reduced voltage (talking good sized motors - such as a 13.8kV run at 4160V). I understand in the motor world, 600V is still considered low voltage - so they wouldn't test that at a reduced voltage, but only because 600V is readily available. I also don't think it would hurt the VFD - the full load current draw of a 1.5 HP - 600V motor is probably less than 2 amps (with the actual motor winding sized accordingly) - it will not suddenly draw big current (beyond the typically expected inrush). Can you program a current limit into the VFD? No-load means remove the v-belt.

If you were going the other way, with a 240V motor and running on 600V through the VFD (expecting the VFD to protect itself and the motor)? That would be ill advised!

Let us know how you make out. David
 
I paralleled the 2nd and 3rd phase on the input of the VFD and connected it to 240V, and then hooked it up to the original 600V motor for a reality test. Unloaded it works just fine, forward, reverse and from very slow to > 1800RPM.

VFD was a great suggestion, thanks to all.

Can't wait to get my 240V motor, it might arrive today.
 
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