Rather than a line reactor, the devices I linked to (which are filters, mainly capacitive I think) are specifically designed to be put in the power feed circuits of VFDs and similar.
Though I am wondering if your plasma machine has a problem, as I don't think that they are normally expected to kill everything on the same circuit through noise.
It only takes out the I/O communications. The motion control is unaffected. The plasma cutter itself work fine too. I can run the program and I have a remote trigger that I can turn the torch on and off as I want, while the cnc program carries out it's task. Crude but affective.
I will know better once I get the EMI filters. I just have to take it one step at a time. If I make too many changes at once, I won't know definitively what the problem was.
