Unbalanced Phase Converters and Power Loss

For all practical purposes a 7.5 HP RPC running a 2 HP machine should not require much in the way of balancing. I suggest as a first test:

1. Run the RPC with the lathe turned off. Does it overheat?

1. Run the lathe unloaded (no cutting). Does it overheat?

If the answer to either is "yes", then the respective motor is probably defective.

Actually..it sounds like you have lost one leg completly. Might check the voltages at the motor and then see if the motor will run from any other 3ph source. It could be you have lost a winding in the motor as another cause.

Gunner

"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas

Install three 220 volt low wattage light bulbs across the phases. It is the simplest way to monitor the voltages. You can easily tell a 10 percent difference in voltages at a distance. Remember that your phase shift from the converter is only 120 degrees at one power loading unless you can vary the reactance between the phases.

John

That sounds like the motor might not be properly wires for 220.Check it again and check the ohms .