Spark Gap Settings

[fluvannabear]

Hello All:
Been a while but still playing with my EVERLAST CUT-50D and WSME-200 MMA/TIG units but since I got early versions of these items, the manuals were somewhat lacking regarding maintainence and control functions. Still trying to figure out where to set the two current controls on the front panel of the WSME-200 when I am using the remote foot pedal. Not sure if the main current control should be at min or max. And does the Basic Current control work with the foot pedal for pulsed welding? But back to my initial question.

What is the proper distance the high frequency spark gap is to be set at for each of these units? Not having any trouble yet but it has been about a year and want to have the reference information on hand when I need it.

Also working on an new foot pedal that is not a big as a shoebox and easier to operate. Thanks and take care.
Burt

[whitehendrix!]

i was told .030" but for that machine, i really don't know.. i have a Super 200P... that may at least give you a general gap though.. liek i said, no promises on if that's correct or not for your particular machine..

i'm pretty sure the on-board current control is overridden with the foot pedal plugged in. been a while since i got to use mine, but from what i can remember, thats how it was.. thats about all i got. hopefully it's better than nothing.

[jakeru]

I did some research on what the purpose of the arc gap is, and how it is used in the high frequency starting circuit. I think I got some answers.

I read somewhere that the high frequency starting circuit is a tesla coil. I did some research on tesla coils, and indeed it does seem to be an exact, (if not very similar) application in our welders.

There is a circuit of the tesla coil in this wikipedia article that I think generally described our welders high frequency circuits, with the spark gap:
http://en.wikipedia.org/wiki/Tesla_coil

Here is the circuit I think ourSuper200P (and likely other similar welders) use, from wikipedia:

The main difference is that the high voltage arcs in our case are emitted by our welder electrode, rather than the indicated "torus" conductor terminal in the schematic.

So... back to the purpose of the arc gap. I believe that its purpose in our circuit is to control how much energy builds up in the "high voltage capacitor" before it gets released (the the spark arcing), and going through the tesla coil's primary transformer loops. I believe that the wider the arc gap, the more voltage would build, therefore the longer the high frequency starting arcs could be. (And possibly you could start welding without needing to hold the electrode as close to the work.) However, too much voltage may damage the capacitor.

A capacitor usually has a voltage rating printed right on it. Too big of a spark plug gap could cause too much voltage build-up, which could damage the capacitor.

It may be more reliable to run a smaller (more modest) arc gap. The size of the gap is proportional to the voltage build-up. Here you can see from this other wikipedia reference...
http://en.wikipedia.org/wiki/Spark_gap
... "Air breaks down at about 30 kV/cm, depending on humidity, temperature, etc."
Assuming that figure is applicable to our arc gap, here are the amount of voltage that would build up for various arc gaps:
.020" arc gap: would allow ~1,500 volts to build up
.030" arc gap: would allow ~2,300 volts to build up
.042" arc gap: would allow ~3,200 volts to build up
.250" arc gap: would allow ~19,000 volts to build up

So... anyone know what voltage the high frequency starting capacitors are rated at? These are the blue ones shown in the attached picture. If someone knows, post up here. Otherwise I'll check it out next time I have my machine opened up. By the way, the high voltage transformer of the high frequency starting/tesla coil circuit, is shown pictured at left.

[jakeru]

Just to update on my previous post on the high frequency arc gap and capacitors specifications...

I found my HF capacitors in my Everlast Super200P are rated at 15,000 volts.
There are two of them mounted in parallel, and they have the following on their labels:
"HCVA"
"15KV"
"751M"

The "751M" based on my research means 750 picofarad mylar capacitor (75 picofarads x 10^1 = 750 pf) according to the capacitor code decipher from http://wiki.xtronics.com/index.php/Capacitor_codes
(This info may come in handy if any of you has a similar welder with a dead high frequency starting function...)

Also I attached a picture showing how to determine the spark gap size, using a feeler gauge. I found I have mine set up right now at .060" (which based on my previous post's theory would I suppose, allow 4,600 volts to build up across the 15,000 volt rated capacitor.) It seems to be working well and reliably, tested across both TIG and plasma functions, and switched back and forth a few times between.

Based on the theory, a HF gap of .195" would "max out" the capacitor's 15,000 volt specification (and with zero safety margin.)

For anyone's gap that is around or above .195" with this type of welder, I would think there is a good chance your high frequency function is going to fail.

I have tried a smaller hf gap before, around .020"+, and I think I had problems with the high frequency starting reliably in plasma mode. It may have been more difficult in TIG mode as well but I don't recall well enough really to say. I found with a good ground and bare metal starting spot, plasma (as well as TIG) is starting well at .060". Perhaps best of all, my welder seems to be "living" and working quite reliably.

I hope this info proves helpful!

[fluvannabear]

Thanks to all who replied. Will check my units and see what the gaps are before I develope any problems. Again thanks. Take care. Burt

[lugweld]

I believe the recommended spark gap on THAT machine is around .030. 0.060 is a little wide.

[jakeru]

Re: gap settings, I just found in my notes (a previous message board post ) that my Super200P was factory delivered with spark gap of .042". (I realize however that does not mean it's "best".) Just FYI.

Also, I found it interesting that apparently not all high frequency board are created equal for all Super200P's... I found in the picture attached below (taken from this thread here: http://weldingweb.com/showthread.php?t=24290 ) someone else's Everlast Super200P high frequency board has a slightly different circuit board, with just one high voltage (larger blue round) capacitors (whereas on mine, there are two.) (I'm talking about the cylinder-shaped blue capacitor on the right side of the pic, right next to the HF spark gap.)

[jakeru]

Update: I took the cover off my Super200P, blew the dust out (there was a surprising amount in there just from being in a dirty garage), and I checked, adjusted and cleaned the spark gap as routine maintenance, and also tried a smaller spark gap setting of .030", which was previously recommended in this thread.

After adjusting the spark gap from ~.060" down to .030", and cleaning my ground clamp, I find my torch is starting more reliably in AC mode on thin metals with super low amps and a small, sharpened tungsten. (Stable arc on a sharp 1/16" tungsten with as little as 3-4 amps.) Before it wasn't starting quite this nicely; although I suppose I can't say for sure whether it was a result of the spark gap adjustment or the ground clamp cleaning.

PS - one tip for finely adjusting the amps on this kind of machine: if you put the machine into "stick" welding mode, you can freely watch the panel amperage readout to see "in real time" what the machine would be trying to weld with, while not triggering any high frequency starting arc starting or using any shielding gas. It even works while using a footpedal and/or pulsing! (To distinguish between the "peak" and "background" current levels, try decreasing the pulsing frequency to the minimum.)

[Ken Smith]

On the Cut50D, is the .030 gap still working ok for you? I have a new CT520D, generic brand, and wonder if the gap should also be in the .030" range. What are your thoughts on compatible specs?

ken

[Jake98]

These points are stationary? and they spark continuously when welding? If I have that right it sounds like a recipe for failure to me.. or at least constant maintenance..

[Jake98]

Originally Posted by Jake98

These points are stationary? and they spark continuously when welding? If I have that right it sounds like a recipe for failure to me.. or at least constant maintenance..

forgot my disclaimer: I don't know jack about welders..

[jakeru]

Jake98 - The high frequency spark gap arcs only during arc starting (high frequency starting.) Once the main welding current kicks in, the high frequency circuit stops.

[mechanic416]

jakeru, I see you useing a metal feeler gauge to set the HF points. That is a NO-NO you should be useing plastic feeler gauges. Unless you like to get a ZAPPPPPP

[Jake98]

Originally Posted by jakeru

Jake98 - The high frequency spark gap arcs only during arc starting (high frequency starting.) Once the main welding current kicks in, the high frequency circuit stops.

That sounds better, thanks Jake, sorry for the 'profliggeration of misinformation'..

[zoama]

Originally Posted by mechanic416

jakeru, I see you useing a metal feeler gauge to set the HF points. That is a NO-NO you should be useing plastic feeler gauges. Unless you like to get a ZAPPPPPP

The metal ones are fine once the caps have discharged.

[Ken Smith]

From my understanding, if the machine sits overnight, the capacitors discharge on their own, and one can use metal feeler gauges. It worked for me two days ago, no ZAP. Mine is at .030 from the factory.

[mechanic416]

Silly me I forgot that everyone that reads this forum went to electronics school knows to discharge the capacitors before checking the spark gap with metal feeler gauges.

[soutthpaw]

[quote=mechanic416;590591]Silly me I forgot that everyone that reads this forum went to electronics school knows to discharge the capacitors before checking the spark gap with metal feeler gauges.[/QUOTE
Heh reminds me of the time I was in Brekenridge sking and some high school kid couldn't get his grand cherokee to start so I had him hold the plug wire while I cranked it over. His buddies all thought it was hilarious. But at least we know it had spark. Choke plate was not openommg enough. There was a TSB out from jeep about high altitude starting issues. But being a HS shop teacher at the time I made it a good learning experience.

My old Airco 300 had a .007 spark gap just for fyi.