New guy 3ph Welder to single conversion

Myst69 · Aug 31, 2018

Hi guys I’m new here and it seems like I’ve come to the right place for my inquiries. I have 2 slightly older cv power sources (miller, airco) that I would like to be able to use at home but I don’t have the 3ph power to run them. I’ve read over a couple of the conversions achieved here and it gave me hope. I am a fabricator/Welder and have been for a few years now but haven’t messed around to much with wiring and diagrams so that’s why I’m here I would appreciate any assistance I can get. Thanks for your time this site is awesome

pics of the machines in question soon to follow.

medsar · Aug 31, 2018

Others will be able to comment more intelligently than me. If you have to change the internal wiring of one of those old welders to convert to 1ph....at first blush, I would say to stray away from doing that. Old Miller/Airco 330 A/BP or Dialarcs can be had from the dealer for $500 bucks here in the PNW. Also, mis-wired welders can be dangerous. If you don't know how to read a schematic to convert it from 3ph to 1ph, then it's best not to do it. Not being mean -- I follow that rule in my shop (If I'm not 100% sure, I don't do it).

Myst69 · Sep 1, 2018

I appreciate your concern, the only reason I’m asking about this is because these welders will be scrapped otherwise. I’m a firm believer in the saying: “they don’t make them like they used to” and I would hate to see them go to waste like that. I have some electrical knowledge but it’s geared more towards residential applications. Whenever dealing with electrical components I’ve always chosen to air on the side of caution, that’s what led me here, I’m just curious if it’s something I could attempt or not given my current understanding.

Myst69 · Sep 1, 2018

Here is the Airco, which according to the faceplate was made by esab

And the Miller

both in pretty decent shape considering I grabbed them for next to nothing.

Myst69 · Sep 1, 2018

I was also considering trying it on this miller cp-250ts but I’m gathering that is a slightly more involved process. Again a really cheap welder that was destined for the scrapyard before I seen it :-(

Myst69 · Sep 2, 2018

Well I’ve started tearing into the Airco today, I sure would like some input based on the pics I’ll be posting but I’ll manage until someone else can give me some info. Pretty dusty on the inside but everything looks to be in order, nothing melted or burnt lol

Code: 1555
Serial: R1008005
I don’t know if these have much significance on an Airco considering how many people have had a hand in manufacturing them in the past. Gonna run over to storage and grab my fluke and a 50A 230V plug and outlet. I have my lincoln squarewave tig-355 hardwired onto a 50A breaker on my service panel, I figured it would just be better to wire in a an outlet for ease of use.

SAF · Sep 2, 2018

Find a copy of your esab diagram and paste this into a search engine.

esab conversion "site:practicalmachinist.com"

SAF Ω

Myst69 · Sep 2, 2018

Having a fairly difficult time locating any supporting information/documents for this specific unit, almost all of the manuals looked to be for newer models of esab and there were no mention of airco.

Myst69 · Sep 2, 2018

So it looks like I kinda lucked out here after knocking off the 1/8” dust on the inner wall I think I found one of the Dead Sea scrolls...ok maybe not but the original diagram was buried there and I can make out most of the info there.

Myst69 · Sep 2, 2018

Since I don’t have 460v and that’s what the terminal link is set at I’ll start by reconfiguring that to 230v.

Myst69 · Sep 2, 2018

So my main question to begin with is since I’m wiring this 230V single phase which line do I cancel out on the plug end? Looks like L1 goes to the left point of the delta triangle L2 to center and L3 to the right. the abbreviation TI is for main primary and L2 goes to the primary terminal

Myst69 · Sep 2, 2018

I can’t locate a clear copy of this diagram anywhere on the net??? Kinda frustrating, it sure would make this process much easier. From looking it over it does appear to only have 2 windings and some booster circuits, I don’t even know where to begin with those.

cyanidekid · Sep 3, 2018

"a little knowledge can be a dangerous thing" comes to mind... it's a bit hard to read that diagram in your pictures, but I'm pretty sure that is not a delta wound transformer. (why are you trying to find it on line when you have it in the machine?)

the Miller is going to be far easier to get info on, contact them directly, and ask if it was available in single phase version. ask them if it can be switched without changing transformers. if so, get the diagrams for the single phase and three phase versions and compare the part numbers. If the transformer is the same you are in luck. wire it as in the single phase version, switch out any other differing parts, and you are good.

others with more knowledge of transformer design will chime in, I'm sure, but most of the info you see on this site regarding running machines built for three phase on single phase are for motor loads, and transformer loads (particularly in welders)are FAR, FAR different animals. please do use caution.

Myst69 · Sep 3, 2018

I was looking for something a little clearer, I might be a little confused about the delta and wye wound differences since this is the first machine I’ve considered converting. With that being said I’ve read somewhere that this machine can be run single phase by cancelling out one of the 3ph legs with major decreases in output, can running it this way be dangerous/detrimental to me, the equipment or the service panel powering it? I am aware these are all very green questions and that is why I chose to come here for input from people who have done it safely and successfully. Again any input is greatly appreciated and of course, before powering on any equipment I will be making absolutely sure that all necessary precautions are in place earth grounds, breakers and extinguishers just in case lol.

Myst69 · Sep 3, 2018

Ohh and the reason I decided to try the airco first is because the cp-250ts has the slope issue and is a little more involved, figured this would be a good one to educate myself with first. The other miller is a viable option but is currently buried in storage :-( although I am tempted to dig it out and have a closer look.

Myst69 · Sep 4, 2018

Went ahead and grabbed the miller cp-300, figured it to be a better choice to educate myself with

Here’s the inside, not to shabby everything looks to be in order. Went to the miller website and grabbed the diagram.

tjb836 · Sep 5, 2018

You probably want to take a look here:https://www.practicalmachinist.com/...-phase-conversion-269124/?highlight=haas-kamp

Myst69 · Sep 5, 2018

That’s actually the thread that I’ve been gathering most of my info from, it’s been a major help in defining the process to my level but now I just have to wait for the capacitors to arrive. I’ll probably start re-wiring it later this week or the weekend. I’ll take as many detailed pics as possible as I go and post them here.

Myst69 · Sep 8, 2018

Okay so I’ve ordered my run capacitors and resistors and I decided to go ahead and start the re-wire process. When I removed the two bolts that hold the terminal block on I was quite surprised at the amount of dirt and dust that had gathered there but then I remembered this machine is 25 years old lol duh. I was able to remove a lot of wires that needed to be moved or removed, fan, jumpers etc but then I ran into in issue identifying wire #8 the one I’m supposed to label 2. Upon inspection of the 6 wires that come from the power switch I realized that they are not numbered like the rest have been so which one I am supposed to remove, I am not quite sure??? I did find one in a different location that appeared to be labeled #8 (pretty grimey hard to make out) but it was actually a bundle of smaller wires that went from the terminal board to the 2nd (middle) coil. I figured that can’t be right? I took a picture of the suspected wire hopefully someone will be along to point me in the right direction.

Myst69 · Sep 8, 2018

Oops double posted that pic I know you can’t really make out the number in that pic but it is labeled #8. it’s actually that zip tied bundle of black wires next to it that run from the power switch there is just no numbering on them that I can see??

New guy 3ph Welder to single conversion

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