Welding Tips and Tricks

mechanic416 wrote:I read this thread 3 time till it hit me. You bought a Lincoln Squarewave 200 tig welder and after a few days of use it goes bad, ok it happens. You take it back and they sell you their demo unit and you take it back to the shop and hook it up to the same plug and blow it up.

That tells me you have something wrong in your shops electric system. If the demo was working fine at the dealers then it should work fine at your shop.

Transformer welders can take more electric fluctuation or spikes then inverter's can to a point.

My thoughts as well.

I've read through this thread a few times also and I've been wondering...

What if one of the hot legs was intermittent and the welder for some reason thought the voltage switched to 120v from 240v, and as it did that it got power back on the 2nd leg, I wonder if that would cause the unit to pop something inside the unit? It sounds like a capacitor is blowing...or other component.

I also agree it must be something in the building since the dealer was using the demo reliably at their location, but I don't think we know all the details either...there is some speculation in this thread...

Alan

Or if it’s fed off of a wild leg. He may only have single phase but I’ve seen this happen before. You can’t always detect that it’s a wild leg with a regular multimeter.

Poland308 wrote:Or if it’s fed off of a wild leg. He may only have single phase but I’ve seen this happen before. You can’t always detect that it’s a wild leg with a regular multimeter.

This doesn't sound like an easy problem to track down.

Well if he does have a wild leg then the transformer machine should be much more reliable.

What exactly is a wild leg?

Would it be possible to just run a new dedicated line?

A wild leg has to do with a variable of how the power provider generates the the three phase. If you read between two of the legs with a good true rms meter you might be able to see it. It’s when one of the three legs varies substantially from the other two. That (wild leg) is often higher in voltage and if you are running controls of any kind it often also has a harmonic resonance of sorts that causes interference and surges. In three phase units where they often use single phase for the control power. It can stress electronic boards and cause premature failure. I’ve had to switch the legs that the control power transformer was on, to keep it from cooking electronics. If he’s tapped into power from someone else, and he just happens to have one of his legs of single phase power tied to the wild leg then it would explain why he cooked two inverters so fast. Since this is an issue caused by how the provider generates the power, this would also explain why the local dealers have seen a high rate of unit failures. Running the power through a transformer has a smoothing affect, probably why they have better luck with the transformer based machines. It’s not uncommon to see isolation transformers in controls where, it’s not a step down, or a step up, but the same voltage going into and out of the transformer. Especially in places with big power draws or lots of inductive resonance created from lots of motors.

https://en.m.wikipedia.org/wiki/High-leg_delta

Better than how I put it.

Hi

Just to wrap this up here. First of all thanks, guys, for all your input here. I have had my Precision 225 for a week and a half and used it heavily for a couple of those days on a stainless steel project. Very happy so far. The arc control and starting seems to be every bit as effortless as the Squarewave, although admittedly we don't have a lot of TIG experience to draw comparisons from. Haven't tried any AC aluminum yet. The torch gets a bit warm after heavy use so down the road we may be looking at a cooler, but otherwise satisfied.

We are still using the same circuit that the original machines were on, and haven't been able to identify any problems or even hints of problems on that circuit or anywhere else in the electrical system. I would be delighted to fix something if I could just find something to fix! Someone here was opining about the possibilities of a wild leg in the 3 phase power. I don't have 3 phase in the shop and it's not even available at the road, so I didn't think it necessary to check into that option.