Quote Originally Posted by mark35gun View Post
no neutral on the m/c, the voltages across the 3 phases are 440,440,380, i am sure that the problem exists when the rotary phase converter is turned off without isolating the m/c first as it has done this twice now as soon as the motor shuts down the ammeter shows a current draw of +40 amps which lunches the control, normal running the ammeter shows 2-3 amps with the m/c on, i don't understand why there should be a large current draw when the phase converter is turned off and the m/c isolator is closed, i have no experience of rotary phase converters so i do not know if this behaviour is normal or not
Any chance you could take a photo of the inside of the phase converter?
When you say you switch of the phase converter, how do you switch it off?

My suspicion is switching off the phase converter doesn't actually isolates it's output, so it's still outputting 2 phases at full voltage, along with leaving the balancing capacitors active (aka acting like a static phase converter), which when combined with a switch mode load (aka the FANUC power module), could be resulting in some very high voltages on the false phase.