3 phase inverter welder turning on but doesn’t arc when in use with a rotary phase converter.

Thread Starter


Joined Nov 7, 2016
Hi all, recently I moved to a new place that only has 240v single phase power. I use a 10kw rotary 3-phase converter to run a panel saw and a few other small 3-phase machines. However, I tried to run my stick welder (which is an inverter welder) but it doesn’t arc. I checked the welder at a mate’s factory, and it works fine.

When connected to the converter It turns on and all appears normal (apart from the fan coming on after about 30-40 seconds which doesn’t happen when plugged into grid 3-phase, and it doesn’t Arc). I contacted the welding company (Kemmpi brand) who said the inverter welder should work with my phase converter set-up but offered no plausible explanations or suggestions why it doesn’t. I have checked the converter output volts which fluctuated quite a bit but were approximately:

L1-L2 = 391 volts

L1-L3 = 413 volts

L2-L3 = 410 volts

(average volts 405v output).

Amps under panel saw load are ~3-4A

All specs appear in tolerance for use with the inverter welder but no joy? I’d be very interested to know if this has happened to any of you, or any suggestions would be really appreciated.

One possibility I thought maybe happening is if the rotary converter voltage is fluctuating too much? I don’t really understand how an inverter welder works so I am left scratching my head? Any troubleshooting suggestions or solutions are very much welcome!

Lonk to Video of voltage fluctuation here:

Screen Shot 2019-08-14 at 8.02.28 pm.png

Thread Starter


Joined Nov 7, 2016
Hi everyone, just a quick update. I managed to find one issue that I hope will solve my problem. One of the motor capacitors looked more like watermelon than a straight can. You can see in figure 2 (far left capacitor next to the black box with a heat sink). I took it out of the system and tested it. Sure enough, it was dead! I am waiting for a replacement to arrive. Does any think this may be contributing to the electrical fluctuation we are seeing in the video? If you think so, I'd like to hear a possible explanation of how? Hope when this is fixed, I'll be able to run the inverter welder :)