Interference from TIG arc starter

Hi. I recently bought a funny old TIG welder on craigslist. It is a small AC buzzbox connected to a Power Kraft arc starter (made by 21st
Century). I tried it out, and it kind of works, but it creates a lot of interference.
I figured that it might be bad for TV watching or radio reception, but it is much worse. If it is plugged into a GFI outlet, the GFI trips after a few seconds of operation. If it is plugged into a non-GFI outlet, it makes any fluorescent lights plugged into that outlet flash and flicker. Also, it will still trip the GFI outlet, if there is a power cord plugged into it (doesn't have to be on). Now I can understand why they don't let you plug unknown loads into hospital outlets. Too risky with the nuisance trips.
I tried installing a line filter between the line and the HV transformer in the arc starter box, and it does not help. Does this mean that the arc starter is radiating power from the leads? I also tried grounding my welding table, but this does not seem to help either. I guess it is possible to use the non-GFI outlet, but then lighting is a problem.
Any way around the pesky GFI trips and light flashing problems? Would it be better to put chokes on the HV side?
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Problem is that the AC buzz-box does not have a shield between the primary and secondary. The HF, not being 60hz, is not coupled across the windings in a balanced manner. The result is two problems. Too much HF on the line and unbalanced currents causing a GFI trip. The only solution is to get a better welder.
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I would begin with the assumption that the arc starter is defective. It should not trip GFCI. Try measuring current on the ground line when it is not plugged into GFCI.
i
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On Nov 27, 4:21 am, Ignoramus17419 <ignoramus17...@NOSPAM. 17419.invalid> wrote:

Hi Ignoramus. Thanks for your suggestion. I kind of think that it is the EMI, but I think that I have a way to test it. First, I will plug the arc starter into the GFI outlet with the line filter in. If it doesn't trip, it may be a noise issue. Second, I will unplug all cords from the GFI outlet (antennas) and see if it still trips with the arc starter plugged into the non-GFI outlet. (The GFI outlet still trips, even if the arc starter is plugged into another outlet, but I did not unplug all lines.)
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snipped-for-privacy@gmail.com wrote:

I'd go along with Iggies comment about there being something wrong with the starter. I had an old add-on HF unit fitted to an oil cooled stick welder and never had any issues with it causing electrical interference to lights or any TVs, computers etc on my circuit or my neighbours. One of the first things I did when setting up the welder in the garage was to check with my neighbours that it didn't effect their TV which was about 8ft away in their living room, no effect noted ever, maybe 3 intervening block work walls helped.
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snipped-for-privacy@gmail.com says...

My Craftsman high frequency unit works fine. It is on all the time, not just for starting unless you switch it off. It has the best start of any tig welder I have used, it will light across a 1/2" gap! If you lay the torch down on the concrete floor there is a blue glow around the electrode. I did lots of welding with it many years ago.
--
Dennis


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On Tue, 27 Nov 2007 06:21:44 -0600, Ignoramus17419

Probably not defective. Those things generate a prodigious amount of EMI and there really isn't any simple remedy. They can also raise hell with computers and security lights.
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Hi Don. Thanks for the reply. I am afraid that you are correct. I disconnected the welding leads, and the problem went away. Apparently, the HF is coming out of the leads and getting into the plug cords of various appliances. Now I understand why the manual recommends running ALL power leads in grounded conduit. What a huge hassle. At least I'm welding now. Gotta to keep from dipping that tungsten. Good thing that there are a few packs in the kit.
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wrote:

my Synchrowave 200 knocks out sections of the local area network when in use.
I dint have enough time to see if it was the DSL or the cat5 drops that were going plonk since i last checked and i plan to move it far away to fix that
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On Tue, 27 Nov 2007 08:03:51 -0600, snipped-for-privacy@SPAMwowway.com (DT) wrote:

The Craftsman HF unit was made by Lincoln, not Century. Big difference! Those were pretty good units.
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Don Foreman wrote:

Ah, that explains it! The HF on my Lincoln Square-Wave TIG 300 is so powerful you can actually weld with it! When I first got the thing, I was poking around with it and was able to get tiny puddles to form with the electrode way too far away for the main arc current to develop. After fiddling for a bit, I found out what happens when you get the electrode closer and the real welding current comes on. Anyway, my Lincoln's HF system is quite awesome, it can create a cloud of 2"+ sparks that look a heck of a lot like those plasma globe things.
Jon
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Jon Elson wrote:

My old Max-Arc would do that also, very impressive, especially when you had it arcing the HF to the end of your finger. Made it tingle a bit but never seemed to do any damage. I don't do that with the Hitachi any more as that is a much more expensive unit but I still get a jolt occasionally when sweaty in the summer month, these days I rest my arm on a wood plank for insulation in those conditions. The old HF unit is on loan to a mate so is still avaialble for trail if I require it.
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You might want to check the setting of the spark gap - that sounds excessive to me. When I got my Airco square wave machine (rebadged ESAB) the HF intensity was similar to what you're describing; I discovered it was enough to interfere with the arc when welding aluminum. Until I adjusted the spark gap per the manual, I was getting better results on aluminum with the HF set to start-only.
The machine was practically new, but inop when I bought it for about $300 at auction. The control board had a shorted small signal diode, which I suspect may have been caused by the HF.
I've owned a Lincoln TIG as well as a couple Millers and the ESAB, and none generated that much HF when set up properly.
--
Ned Simmons

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No wonder why there was such a price difference. The Lincolns sell for a pretty high price on Ebay. They also have a more feature rich front panel. I am determined to make this one work, though.
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snipped-for-privacy@gmail.com wrote:

No personal experience, but I've read that the first step is to clean and adjust the spark gap in the arc starter.
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Hi Jim. The spark gap looks pretty clean. I will try swabbing it with some alcohol to reduce any tracking contamination and reset it to the factory specs. Thanks!
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snipped-for-privacy@gmail.com wrote:

A thought after my previous comment, I did modify my HF unit after awhile to provide control to the transformer with a phase angle controller. That disturbed the flourescent lights in the garage and made them flicker. The controller acted on the transformer to provide a ramp up and down, it was brutal but did work. Is your unit an add-on HF unit or does it do more. I still didn't get any problems with my neighbours though, or my computers. Subsequently I went to an inverter TIG unit.
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On Nov 27, 3:51 pm, David Billington

...
Hi David. This is an add-on unit, and all it does is HF. It has a very standard design. There is an iron cored transformer which generates high voltage AC. It is shunted with a double spark gap, then feeds into an air cored coil. One funny thing is that there is no HV capacitor. There is a low voltage capacitor connected to a tap on the air cored coil. Perhaps the flat wound air cored coil has enough self capacitance to oscillate.
There is no variable control for the HF. It is either on or off. Those little line filters are pretty good at filtering noise at high frequencies coming back to the line, but a thyristor phase control injects harmonics at low multiples of the mains frequency, which can require more aggressive filtering.
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snipped-for-privacy@gmail.com wrote:

Switching heavy inductive currents with phase control is the devil's own work in line-conducted interference.
Years ago, I installed a very sensitive electron beam lithography machine at a semiconductor house in Silicon Valley. We had horrible, non- reproducible problems with it until we scoped the 3-phase coming in. The epitaxal reactor on the other side of the building was making the input power look like something out of Jimi Hendrix's guitar. Both machines were essential so the e-beam machine was only used for critical jobs when the reactor was off.
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On Nov 27, 4:21 am, Ignoramus17419 <ignoramus17...@NOSPAM. 17419.invalid> wrote:

Hi Ignoramus. I found out a solution, but perhaps not the cause of the problem.
I was able to trip the GFI, even though the arc starter was plugged into a non-GFI output. That seems to suggest that the unit was not defective. Then, I unplugged all loads to the GFI outlet. No more tripping! The loads included a microwave oven and a trouble light. No matter. I don't use these while welding, but the trouble light can help start out, since I do not have an auto-darkening helmet.
Then, I tried disconnecting the welding cables from the arc starter. No nuisance trips, and the fluorescent lights stopped flickering when the HF was turned on, but I could not weld.
The compromise was to plug everything in a non-GFI outlet, and unplug everything from the GFI outlet. The lights would still flash, but this was bearable, especially after the arc started.
TIG welding is a blast, especially after developing the skill to stick weld 1/16" sheet metal. I have a feeling that that outdated skill will soon atrophy ;). It will also work for filling blown through holes easily, with no slag inclusions. Just fantastic!
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