PM30 Keeps shutting Down

[ccawgc]

In a lot of inverters, the 2 large capacitor are wired in series, each cap has 1/2 of the buss voltage. So if something goes wrong with one of the caps you end up with a voltage imbalance. Some inverters can detect this and will shut down to keep the cap from blowing up.
There is a resister across each cap. If the resistor fails, this will also cause the imbalance.
I have seen units power up and run for a time then shut down. Also seen them fault out right away on the second power up. I think there are instructions in the manual on how to measure the voltage on these caps and see if they are balanced. Safest way is to power on then after a minute power down. 2 minutes later measure the cap voltage. IF good, the caps should be around 50 vdc. If bad resistor one will be ow the the other will be over 160vdc.
Or use two meters and clip them to the test points and then power up. Then after a couple of minutes power down. At all times both meters should red with in 10 volts.
Always work on a non-conductive bench when working with these units. A short to a grounded bench can cause an explosion or arc flash. Causing you to be injured.

[N2 Welding]

+1 ^ good info.