On Wed, 12 Jan 2005 09:50:13 -0600, "Tim Williams"
wrote:

Err, so TIG doesn't need a current-limited transformer?

Yes, it does. TIG and stick have essentially the same electrical
characteristics. They are called "constant current" or CC machines.
They are not necessarily electronic, e.g. Miller Dialarc HF.

A V vs I curve with varying resistive load would look like the first
quadrant of an ellipse. Voltage is fairly flat at the top (open
circuit, high load resistance) region, but the curve is nearly
vertical (constant current) near short cct condx. OCV is typically 60
to 80 volts, arc voltage is typically about 24 volts.

This sort of VI characteristic is also typical of oil ignition and
neon sign transformers. It is achieved with leakage inductance in the
xfmr (often just a magnetic shunt), though welders do sometimes have
additional inductance as well.