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Tig Welder

sk1nner

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#1
I was given a Miller Econotig from work. It's said to work good. The only problem is that it runs on 460v single phase, 33 amps of it. I (obviously) don't have 460 in my garage. I removed the cover and inside was this diagram 20151106_190520-1.jpg I'm no electrition so I need some help figuring if I can convert it to 220 single phase. If this makes sense to anyone please, any info you can lend me is greatly appreciated. As always, thank you in advance.
 

Hawkeye

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#2
The drawings themselves don't give an easy solution, but if you open the welder up and look at the main transformer itself, you might find extra wires or terminals coming out of it. If so, it's just a case of moving the second incoming wire to the appropriate terminal. You will be drawing quite a bit more current at 220V, so I'd plan on running a 50 amp welder outlet.

An easy alternative would be to source a 220 - 460 transformer, but it would need to be around 20 KVA to give you full use of the welder. And again, that would need to be fed by at least 50 amps.

If you do find extra taps on the transformer, post a picture so we can better advise you.
 

sk1nner

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#3
I disn't see any extra wires inside, bUT i can taka a nother look. What I wonder is in the diagram I see there is a circle with FM inside if it. What does that mean? I calculated it out and I would need a 15180VA. Do you think a 15KVA transformer would be adequate? I've looked on ebay and I see a whole lot of 460 to 220 step down transformers, those can be used backwards to increase the voltage right? Thanks for the info
 

David VanNorman

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#7
If you was able to set it for 220 it would take like 66 amps to run it. I think you might put it on E-bay. It is not for a ham and egger.
 

Hawkeye

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#8
You would need 15180 watts if it was a resistive load, but, since it is a highly inductive load, the VA should be rated higher.
 

Tony Wells

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#11
On the main diagram, T1 shows to have a 230 primary. The additional diagram is a supplement where it came factory wired for 460. Probably a different transformer. Before getting too excited about it, I'd get a price on a replacement T1. Yes, probably plenty of money, but cheaper than a whole new welder. Check that PC1 has the same inputs as shown. I would presume so, since there is no other schematic.
 

sk1nner

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Active Member
#12
FM most likely means fan motor. If I had it I'd seriously consider rewinding the primary for 240.
Could you please elaborate on this? I've done a little bit of research but it sounded like I would need a thicker wire (they say it's magnetic?) And half as many windings. Does that basically cover it?
 

sk1nner

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Active Member
#13
On the mail diagram, T1 shows to have a 230 primary. The additional diagram is a suppliment where it came factory wired for 460. Probably a different transformer. Before getting too excited about it, I'd get a price on a replacement T1. Yes, probably plenty of money, but cheaper than a whole new welder. Check that PC1 has the same inputs as shown. I would presume so, since there is no other schematic.
From what I've seen it looks to be about $700 . Would a step down transformer used in reverse work? They seem to be a lot more affordable. Thank you
 

John Hasler

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#16
Could you please elaborate on this? I've done a little bit of research but it sounded like I would need a thicker wire (they say it's magnetic?) And half as many windings. Does that basically cover it?
I'd make the existing winding into two paralleled windings. Exactly how I did it would depend on what I saw when took it apart.
 

Tony Wells

Former Vice President
Staff member
Administrator
#17
Using a stepup transformer is one way to go, but like John says, extra care around 480. It's not forgiving. I'm not really sure how that transformer would be to be sized, with out thinking about it some. You know the demand of the machine, but the transformers I have seen are rated for stepdown use. I suppose energy is energy and the same ratings would apply either way.
 

jim18655

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#19
Using a stepup transformer is one way to go, but like John says, extra care around 480. It's not forgiving. I'm not really sure how that transformer would be to be sized, with out thinking about it some. You know the demand of the machine, but the transformers I have seen are rated for stepdown use. I suppose energy is energy and the same ratings would apply either way.
Transformers aren't as efficient in "reverse" as they are in the way they're designed to be used. It has to do with the magnetic flux around the core and the position of the coils.
 

John Hasler

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#21
So I could actually use the same wire, just double it up. That sounds interesting. I may look into this more. Thank you.
Well, I said *I'd* consider trying it, but I'm an electrical engineer and also a little bit crazy. Whether or not I actually would try rewinding it would depend on what I found when I took it apart.
 

sk1nner

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Active Member
#23
You have sparked my interest in doing this. I don't want to mess anything up, could you give some tips. I know I will have to be careful with the wire. But what else should I look for?
 

MozamPete

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#25
Looking at the first post with the circuit diagrams, I would say the fan motor is 230Vac in both configuration (230V or 460V supply), so if you just disconnected wire '11' from the switch to the transformer and reconnect from the switch to the transformer terminal wire '13' connects to you would get all the correct voltages out of the transformer when running on 230Vac (the 24V control supply, supply to the electrode, etc). You would probably still only be able to draw the original 33 amp from the supply without risking burning out the transformer primary so would need to de-rate the welder output to around 1/2 current - but you could easily add a fuse or circuit breaker to the input to protect against that and give it a try.

Clipboard-1.jpg
 
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sk1nner

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Active Member
#26
With wire 13 being 230v, logically wouldn't there be the other end of that wire somewhere? Or would it actually splice off of the 460 coil winding?
 

MozamPete

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#27
That's what the circuit diagram is showing, 460v across the entire primary with a tap off half way for the fan motor (which I'm assuming is 230vac). It is called an auto transformer and can be done with only one winding needed, and also work the other way round - when you put 230v on as show in my markup you will get 460v at the unused end so make sure you insulate it and don't just leave a wire floating around.

As you haven't increased the wire size you as still limited to the original transformer current limit - which is probably something just above the 33A quoted supply requirement, but how much above is unknown unless you can find some actual markings on the transformer.
 

RJSakowski

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#28
According to the manual, there is over temperature protection circuitry so you could probably still use to full capacity, just derate the duty cycle chart accordingly.

If the tap for the fan comes out from the winding (and is 230v), you may be able to split the primary winding there and reconnect the two halves as two parallel windings.
 

sk1nner

Active User
Active Member
#30
Yes the fan is 220v. So I can input 220 to the "fan" lead (#13) and power the welder, this is great news. I really can't express how grateful I am for the info guys, you saved me a lot of time and money on this. Thank you!