"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"azotic" fired this volley in news:k1o556$fua$1
@speranza.aioe.org:

The arc voltage of a plasma cutter is higher than the arc voltage

I didn't mean that last to sound like I didn't agree with you. It's just
that the arc gap is quite small in most torches I've seen, and would be
POSSIBLE to have an arc at 30-50V, if you can just get it struck first.

A welder certainly would not work on a blow-back start torch, but I wonder
if it would work on an old-style one with high frequency to initate the
arc.

In my last... _Once the arc has started_, the voltage is a function of
gap,
given constant current.

Lloyd

I believe you need a constant voltage source to generate and sustain a
plasma.
The pressure and volume of the gas flowing thru the plasma torch is going
to
determine the voltage needed to establish and maintane a true plasma. Also
the gas conductivity is a factor ( air, nitrogen, argon, etc.) in plasma
formation.
I attempted what you are thinking about doing back in in the 1980's and it
did not work with a conventional welder even with the HF set on all the
time.
I now own an old airco plasma cutter 100A, its old (1970's?) but very
servicable
with descrete components. The dc power supply that runs the plasma torch
produces about 200vdc. I did some reasearch back in the 1980's studying
schematics i aquired from several manufactures of plasma cutters and they
all
ran between 200 to 400vdc to the plasma torch depending on how thick a
material they would cut. As i recall the thicker the material the higher the
voltage
required. Hope this helps.

Best Regards
Tom.
--
http://fija.org/