ARC Voltage

[RTID]

Hello, I'm having an issue with my shop sabre table. I use a hypertherm Powermax 85 with my system. I had to turn the THC off because I don't seem to be getting good voltage measurements. I have done this same process (with the THC on) for almost a year and it worked correctly, but now it doesn't. The target voltage is set to 88 and it reads anywhere from 20 volts to 360volts when cutting. While cutting a long line the voltage doesn't seem to change no matter how close the torch get to the metal. I am getting good cuts and I don't seem to be going through any more consumables. Any ideas?

[adbuch]

I am also running a Hypertherm Powermax 85 on my Plasmacam table with THC. The basic concept is that the controller monitors the "divided" arc voltage and adjusts the cut height such that the arc voltage remains constant. For most cutting, the Hypertherm cut charts spec the cut height at 0.060". In any case, I suspect that you have a problem with the arc voltage monitoring - perhaps the cable, voltage divider, or internal wiring in your plasma cutter, particularly if you did the internal modifications required for the non-CPC machines. I would need more information as to the specifics of your arc voltage monitoring scheme to help you further diagnose your problem.
David

[AZ_guy]

Ive heard that a bad arc voltage or erratic THC can be caused by a bad ground. I had to drive 10 ground rods I think to get good numbers on the light bulb test.