Getting shocked

Jun 20, 2007 5 Replies

I have a Miller 250HF. When I tig weld, aluminum, I get a steady tingle through the filler rod and my arm if rested on the work or bench. It doesn't hurt but is damned annoying. What is wrong with my welder to do this? When welding there is a steady blue arc, many, between the HF contacts. Is this normal? I've been using thin rubber gloves inside my welding gloves. That takes care of the tingle trough the filler rod but it still gets you through the work table.



Thanks for any help.


My guess is that your rod/torch manipulation is not optimal. You are probably keeping the rod too close to the arc and not doing a properly timed dip of the rod into the leading edge of the puddle, then withdrawing the rod (but keeping it within the shielding gas envelope) as you move the torch forward to advance the puddle. This would result in melting the tip of the rod with the arc and letting it drop into the puddle. This causes the HF to go to the rod instead of the work.

awright

Sounds like your ground setup needs some looking after. It would be more than just a tingle if you were getting the HF component. Check for a wire inside the welder abraded to the frame, both welding side and incoming power side.

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To the OP: Your clothes are not damp, are they?

I don't really understand the part about the steady blue arc between the HF contacts, but if my clothes are damp, I get tingles - and sometimes just plain knocked on my arse!

The steady blue arc between the HF unit contact points is normal because the HF is on continuously for AC TIG on aluminum. The air between those contacts breaks down due to the high voltage across them from a line-powered transformer with a high voltage secondary winding. The resulting abrupt shorting puts an electrical pulse containing very high frequencies into the primary of a second transformer that couples the HF into the lead to the torch. The HF and, thus, the blue arcing has to be continuous to minimize the rectification inherent in the differing potentials at which the welding arc restrikes between the tungsten and the hot aluminum on each half cycle of the AC welding current used for aluminum.

I concur with the comments above about the possibility of a poor ground causing your discomfort.

awright

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