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Running the CP302 off 20hp RPC

Paul Cataldo

Stainless
Joined
Dec 9, 2004
Location
Atlanta, GA
So I am now successfully welding with the Miller CP302 off of my 20hp RPC.
I know quite a few guys are running their welders off of RPC's in some fashion or another. I have also heard from some guys that this can damage a welder in some way, but exactly how, I do not know?
This CO302 is a transformer machine.
I would like to know if anyone here has actual knowledge of a welder ever being damaged, due to powering it via a phase converter? Is this even possible, and if so, what exactly would it damage?
 
I've seen on a few of the RPC manufacturer sites, that welders (resistive loads) are ok, and apparently are fine. But here again, I'm looking for more info on the subject in both regards.
 
So I am now successfully welding with the Miller CP302 off of my 20hp RPC.
I know quite a few guys are running their welders off of RPC's in some fashion or another. I have also heard from some guys that this can damage a welder in some way, but exactly how, I do not know?
This CO302 is a transformer machine.
I would like to know if anyone here has actual knowledge of a welder ever being damaged, due to powering it via a phase converter? Is this even possible, and if so, what exactly would it damage?


If your rotary converter can carry the load, at the duty cycle you demand (the 302 DOES have a 100% duty cycle rating in power curves shown in the owner's guide), then it should be fine.

The CP-302, being essentially same as the CP300 series, can be set up to operate on single phase WITHOUT a rotary converter, provided it's a 230/460v version, using same process as the CP-200 and CP300... and it'll burn wire like Hades doing it...
 
Thanks for the reply Mr Kamp. Indeed the 302 is now running seemingly fine on the 20hp RPC without issue. I have yet to do any real current/voltage measuring but will in time. It does seem to be operating at or very near the recommended MillerWeldCalculator app settings for each given thickness of material.
With regards to the 1ph conversions however, the more local Miller Tech repair guys I speak to, the more respect I gain for your electrical knowledge. Of all the shops I've spoken to, only one has been accepting of this info and ever thought it even possible. All others have pretty much thought it crazy for even considering your ideas, and basically swear it cannot be done! Thanks so much again.
 
Hi Paul, and thanks for the kind words. I've been referred to with many terms stronger than 'crazy', but I'm sure you'll find plenty that'll promise you that I'm not wrong. The CP302 is essentially the 'robot-spec' non-computerized serious-duty unit essentially carried over from the CP-300. It'll have different cosmetics, and it'll use SCRs in the main rectifier, rather than a contactor, to eliminate wear from the contactor banging shut and arcing on open. Other than that, it has a heart of copper and iron... they're about the most bullet-proof machines ever to melt metal in a shop.
 








 
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