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Whats purpose of the Spark Gap

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Re: Whats purpose of the Spark Gap

Postby aland » Mon Feb 05, 2018 3:07 am

Richr wrote:does anyone have a clue what the spark gap does.... Just adjusted it on my Everlast power TIG 200..
it was .038 and adjusted it to .030.. Made the arc steady on the min setting of 20 amps.. At the original setting the arc was cutting out, sounded like I was losing the ground clamp connection.


Rich,

I have a couple Qs. I opened my i-Tig 201 which the manual says there is a daughter board and shows a pic of the points. My machine has no daughter board, and I can see the points, but they don't look like the ones pictures in my manual.

I looked in the manual for the machine you have (i-Tig 200 ????) and I don't see the points shown there.

Is it the i-Tig 200 you have?

I don't see any locking nut and I do see a very small screw on one side of the two posts, but I think I would need to remove the mother board to adjust and set up.

Does your unit have the locking nut for the point gap adjustment ?

I think I may need to call Everlast.

Alan
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Re: Whats purpose of the Spark Gap

Postby Richr » Tue Feb 13, 2018 6:45 pm

Allan

I have a power TIG 200 DV. The only problem I had was erratic arc on AC..

It was easy to adjust the sparkgap two locking nuts and two screws... it was at .038, adjusted it to 30..
it seemed to fix the problem... still not great at low amps.. but better
Richr
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Re: Whats purpose of the Spark Gap

Postby aland » Tue Feb 13, 2018 6:54 pm

Richr wrote:Allan

I have a power TIG 200 DV. The only problem I had was erratic arc on AC..

It was easy to adjust the sparkgap two locking nuts and two screws... it was at .038, adjusted it to 30..
it seemed to fix the problem... still not great at low amps.. but better


Rich,

Mine looks different than they show in the manual, and I don't have the locking nut. There looks to be a very tiny copper phillips head screw (my wife would call a "plus screwdriver" ;) ), but it seems I would need to take the entire motherboard out of the machine to adjust it. I posted a message on the Everlast forum, will follow up there and see what they say, but it seems they must have changed the i-Tig 201 which I have, sometime after the manual was printed.

Alan
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Re: Whats purpose of the Spark Gap

Postby Bill Beauregard » Tue Feb 13, 2018 8:22 pm

I don't fully understand spark gap. I have pieced together a few facts:
Sine wave TIG power in AC when viewed on an oscilloscope, is a curvy line. Each half cycle, current tapers down to zero, then gradually builds in the other direction.

When we weld aluminum, most older transformer welders are balanced flow current, or 50/50 balance. As argon is not relatively conductive, it must be ionized to easily conduct. Imagine a bolt of lightning. If we could see faster than we can, we would perceive steps in a bolt of lightning. A space in ionized air conducts, electrons stop at the edge of ionized air, billions of electrons rush to this point, but are unable to move until sufficient power of electrons ionize another volume of air. Then these electrons surge forward, and the process repeats. In a bolt of lightning, each step happens so fast that our eyes can't see each step. We see it as a crooked bolt of lightning.

Welding in AC, many transformer based welders are fixed at sixty HZ. direction of electron flow reverses 120 times per second.

Electrons flowing from the pointed tungsten ionize easily. Electrons flowing from the workpiece find it more difficult to ionize shielding gas. There is more surface they are spread over, and if welding aluminum, oxide layer is less conductive than clean aluminum.

If we didn't have HF, an overrunning high voltage, low energy high frequency power source, ionization of shielding gas would have to be recreated 120 times per second.

A 1960 car used collapsing magnetic field to induce high voltage, low energy electrical charge, igniting gasoline/air mixture. Something similar happens in the HF circuits in transformer welders. The spark gap fires, dissipating a build up of electrons, then pressure falls, interrupting flow. The magnetic field in a transformer coil collapses. This collapse, brings the magnetic field across transformer coils, inducing high voltage.

varying gap changes the intensity of this process. greater HF increases radio interference. There are things you can do to reduce a problem.

Spark electrodes should be polished. sandpaper makes thousands of scratches, interfering with ionization.
Bill Beauregard
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