CNC Plasma

Hello everyone!

I got my machine (cnc plasma/ox-acetylene torch) working with the
oxy-acetylene torch. I am using a solid state relay to turn the cutting
oxygen on and off through DeskNC. I finally built an adapter to hold my
hand plasma torch and connected the trigger wires to the relay. I wired the
relay in parallel with the trigger on the torch. Two problems arised. The
relay doesn't turn on the torch until I press the trigger and will only shut
off (through software in DeskNC) when I press the trigger again. The second
problem is that when I bypass the relay and just connect the 2 wires
together to watch it cut, the steppers went crazy. Once the torch was off,
the steppers operated normally. I suspect the crazy running steppers is due
to high frequency being generated by the plasma arc, aprox 50K volts.

The relay I have is rated up to 330 ac volts @ 40 amps. It appears the
trigger voltage for the plasma torch is 12 volts dc and low amps (22ga wire
on trigger circuit). Is there another relay I need to use or is there more
circuitry I need to add to output side of the relay?
Also what would be the best way to isolate the high frequency from the
controller board?

Thanks,

Dave Johnson
Denver, Colorado