Some fun, maybe? UPS to Welder

[Shane@profab]

Hi ya'all

I dont know how to say this without sounding Obsequious but I am dead impressed with the general electrical knowldege that gets nadied about on this forum.

So I reckon this is the best place to pose this question - after successfully hooking up my Tig machine to the transformer (see old thread - still cant post piccies), I even managed to effect some board level repair on the control circuit, I thought I was real bright - my wife has subsequently corrected me, anyway I digress

In the same spirit of reserection, I have an very cool UPS that was tossed out cos the battery pack had died and was too costly to replace.
So while casually reading about inverters and stuff and cursing that my Tig machine cant weld AC, I thought, why not convert the UPS to a welder?

Surely its in essence a big rectifier to charge the battery pack and then an inverter to take that DC off the battery pack back to AC?
So if you could tap into the charging circuit, you would have a DC machine and if you tapped into the invereter, you would have an AC machine?
Ok the voltages are probably going to be a bit of an issue, the DC battery pack as 22 x 12V batteries in series, so you have a whopping 264 volts on the DC side.
The input side is rated at 220V 63 Amps, output is 10KVA, 25 Amps 220V

So, what you think?

[ZTFab]

I think that if you're going to use words like, "obsequious" and "digress", you should learn how to spell words like "resurrection":laugh: J/K

I don't think you're going to be able to get a UPS driver to convert over to a weldor. They have too many benefits and vacation time they would have to give up.:p

[Sandy]

Surely its in essence a big rectifier to charge the battery pack and then an inverter to take that DC off the battery pack back to AC?


Yep, there are several grades of UP Systems. The most basic of which is to provide only backup AC when the commercial AC is bye bye. Then the next added step up is to provide for the buffering or isolation of the input before it gets to the sensitive equipment on the other side. It is in this buffering section where things can be either the most basic or become quite elaborate. The most elaborate being where any metallic connection to the outside world is electronically eliminated, thus total isolation from any outside influence or exterior events. Cost is proportionate. You'll have to research the one you have to determine where in that range it was designed.

But back to the topic. What you have on hand is many of the components that two welders or one multi-purpose welder may or may not have. I'll fall back on the cost issue here. A lot will be determined by how much you are willing to spend filling in the missing pieces. Basically what you will be doing is building your own welder(s) with a free cabinet and some components. Things to think about will be the maximum out put voltages, currents, adjustability and potential limitations.

It'll be a good learning experience if you enjoy working with electronics and have the time and resources.

[Shane@profab]

ZTfab - Do you wear a skirt....only reason I ask is that I am married to an english editor and I constantly get my spelling corrected....so now run off an get me a cup of tea:)

Sandy, well the essence is to play and learn - I need something to keep me away from the TV when there is no motor racing on!. Its quite a fancy UPS, I dont have all the data on it yet (when the manufacturer heard I had it and that it might get binned, they VERY quickly assured me that they would come collect it) Its an online type so it must have line voltage/qaulity montioring capability but I dont see that part as being the NB bit.
It has two, what I think are IGBT's hooked up to some serious caps on the DC link, so there is your smoothed out DC supply, after that I am lost. The IGBT's are force cooled and the base has the usual bank of heavy tranformers.
Yes I agree that getting the combination of low volts and high amps is going to be the tricky bit.

Shane

[ZTFab]

ZTfab - Do you wear a skirt....only reason I ask is that I am married to an english editor and I constantly get my spelling corrected....so now run off an get me a cup of tea:)


Shane


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