On Wed, 19 Apr 2006 00:09:37 GMT, RoyJ wrote:
Most of the boxes are rated for the max heat dissaption possible from
the core.

You are right, but, I suspect, this is a special case.

Also, since it is rated at 200 amps 100% duty cycle, it would be a
great leap from it to 300 amps, 60% duty cycle.

I saw some vague allusions in the manual to higher capacity. (the dig
setting at 200A increases amperage, and also the Programmer manual
mentions simple changes to switch to 300A)

i

Ignoramus19116 wrote:
I have a Hobart CyberTig 200 DC-S welder. It is a 3 phase 200 A rated
SCR fired, transformer based TIG welder.

I have a PCTI's 3 phase firing circuit that is made to control any SCR
fired, transformer based, 6 SCR power supply, by specifying current
and voltage with potentiometers.

It is shown he

http://www.pcti.com/3phfiring.htm

It appears to be very straightforward to wire it (I have a
manual). What I would like to use it for is to convert it to a both CC
as well as CV operation so that I could use it as a TIG/Stick or MIG
welder.

The nice thing is that, it seems, it can be wired without disturbing
too much in the welder. All I need to do is unplug the current
Programmer controller, add some piggy back terminals, and connect this
circuit in. I would start with a simple control for CC and then expand
a little bit by making it control valves, HF and switch from CC to
CV. (CC is set by specifying max voltage as OCV and controlling
current with a pot, whereas CV is set by specifying max current and
controlling max voltage with a pot).

My question for now is this: Is this CyberTig actually a 300 A, 60%
duty cycle welder, controlled to run at no more than 200 amps, or is
it really a 200A max welder. It is specified to have 100% duty cycle
at 200A.

i