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I hope I'm asking in the right place!

I worked with automated TIG (GTAW) welding equipment. I'm confused about how the welding power supply controls the current applied through the work piece. If the entire circuit was a simple static load, with a known resistance, it makes sense that voltage across the load could be controlled to keep the current constant. If I want more current, I increase the potential.

In this case, the arc voltage will drop with increasing current. This can be seen clearly on a diagram of voltage vs. amperage for a constant current welding power supply and is consistent with my own findings. If, during the middle of a weld, I command the machine to produce more current, will the machine increase the potential across the output terminals? I have a suspicion that the dynamic nature of the arc welding aspect of this comes into play. I.E. the conductive plasma region becomes larger once it reaches a steady state at a higher current?

Please let me know if my question makes any sense.

Thanks!

Chris Jarnutowski
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  • Watch this video. He explains this well enough for most anyone to understand it. The SMAW part of his discussion applies to TIG. – jonk Jun 23 '20 at 22:13
  • IMO the drop in arc voltage is the result of increased current going through that arc. Seems logical that the more current is spent, the more voltage drops. – Fredled Jun 23 '20 at 22:45

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