Originally Posted by
jhovel
Maybe I have, Karl. My frustrating experience was that several DC inverter welders I tried to use 7016 and 7018 rods on simply would not maintain an arc at all. I measured the OCV and found the frustrating ones to be below 42V. I then tried my old transformer AC Welder with 55V OCV and it was 'less frustrating', but still not good welds. Re-starting almost impossible without chipping off the flux coating on the rod end. That old tranny has a 'Special electrode' connector with 70V OCV and off she went like a ripper. No trouble maintaining arc, good control, easy re-starting.
I then looked at the specs and the rod packets are actually labelled for 50V min OCV. I looked at other brands and found them more or less all the same.
I then looked for an inverter with higher OCV and measured it. My current Inverter has 55V OCV and works like a charm.
I can only report my practical experience and frustrations and successes.
So I have no idea how the mining people do it. I wonder if the pro inverters switch the VRD off for brief intervals when starting or re-starting and have it on when in use or when not making contact with a rod? In my mind that would work.
Can you help explain my experience? Can others chirp in and report their experience with LH rods on lower end DC inverters?