[lclore]

Jim,
I am alittle fuzzy on some things- may just be staring at this stuff too hard... Would you mind to comment on some of these specific questions related to Hypertherm systems?

In general, does the heated air of the plasma cutter actually do the cutting work or does electrical current thru the work piece contribute (and at what level)? My reading on this says you have to ground the workpiece- with a rotating tube attached to the end of a servo motor, I don't want any current flowing thru the work piece to ground in whatever random machine frame path it chooses as it will create havoc with the controls and servo feedback (oh yeah, and be a possible safety hazard). Is electrical isolation a requirement to the controls with a separate path to ground? Does it need to be a high integrity (low impedance) path to ground? Is this a safety ground only conducting in the event of a inverter output stage failure?

What safety's are built into the HyperTherm Powermax45 inverter in the event of a failed output stage? I didn't see in the manual any recommended upstream contactors or safety devices. Is the enable input safety rated to some level?

Thanks...
Lee