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Running Surplus 3-Phase Welders on Single-Phase Power

dkamp

eMail NOT Working
Hey Everybody-

If you're interested in getting a good welder, but you're on a low budget, used industrial-type 3-phase welders can be found for incredibly cheap prices.

Many people say that three-phase machines cannot be made to perform properly on single-phase power, but Peter Haas and I have found a technique that proves otherwise. I've been working with Millers, but I believe others will work just fine using similar technique.

I've documented the technique and method (no withheld secrets anywhere) and posted them freely, so check it out, and give them a try. If you run into difficulty, or would like to discuss it further, shoot me an Email, and I'll reply, or give you a call.

So far, I've done:

Miller CP-200 (MIG)
Miller SRH-333 (stick/tig supply)
Miller CP-250TS (spray-transfer only- still messing with it to make it happy on short-arc)

Next up:
Miller CP-300
22 Airco 300 MIG supplies (yep... twenty two of 'em)
a Lincoln somethingorother with digital controls

Here's where I've posted the first three:

http://www.practicalmachinist.com/v...ler-cp200-converted-240v-single-phase-199832/

http://www.practicalmachinist.com/v...ler-cp200-converted-240v-single-phase-199832/

http://www.practicalmachinist.com/v...ler-cp200-converted-240v-single-phase-199832/
 

dalmatiangirl61

Subscriber
Last Subscription Date
07/10/2019
Re: Running surplus 3-phase welders on single-phase power

All 3 of those links go to the same post, is that correct? I have a 3 phase carbon arc power supply which I think it is a re-branded Miller machine (stick), if this works on it that would be sweet. Honestly suck at electrical, I'll show this to a friend and see if he understands it better. Thanks!
 

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

Argh... you're right... must'a had copy-paste problems.

CP-200 MIG: http://www.practicalmachinist.com/v...ler-cp200-converted-240v-single-phase-199832/

SRH-333 Stick/TIG:http://www.practicalmachinist.com/v...-vfd/miller-srh-333-240v-single-phase-201310/

CP-250TS MIG: http://www.practicalmachinist.com/v...iller-cp-250ts-converted-single-phase-206509/

That should work better.:bonk:

---------- Post added at 08:49 AM ---------- Previous post was at 08:45 AM ----------

The basic concept of all of these, is that the welding transformer is based on a 3-phase core... having 3 sections, and built so that magnetic flow circulates through the core in a figure-8 pattern.

Wire the far left and far right cores so that they're operating opposite of eachother (criss-cross one). Wire the CENTER coil in EITHER orientation, but pass each leg through a motor-run capacitor of sufficient size to create 90 degrees of phase shift at full load current.

What this does, is force the core to function in it's original design-plan, and once the flux is spinning in a coherent figure-8, you'll get full functionality and output.
 

Matco

Registered
Re: Running surplus 3-phase welders on single-phase power

I know I'm responding to an old post... did you ever convert the Miller CP-300? Could you post your results?
 

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

I know I'm responding to an old post... did you ever convert the Miller CP-300? Could you post your results?
Hi Matco-

I have not gotten to converting MY CP-300 to single YET, but I do have one waiting. I HAVE however, advised several others on converting the CP-300, and all have found success. The general agreement of all, is that 130uF was the 'happy' value for it, and that they weld extremely well on single-phase.

Keep watching- one of them SHOULD be posting his diagram and connection procedure soon... but for a hint... it's very similar to the CP-200, but the CP-300s I've seen so far have all been DELTA input machines, so the mod is substantially easier... eliminate the cross-connections of the delta, break out the primary leads for each transformer segment, and wire in the capacitors...

:wave:
 

Bob Phillips

Registered
Last Subscription Date
08/27/2013
Re: Running surplus 3-phase welders on single-phase power

Back in the olden days and being around a excess of 3-phase motors and knowing a ole smart millwright/machinist, 3-phase can be made/generated from driving a 3-phase motor with a single phase, 22/240 volt, slave motor... I ran my first small machine shop, single phase wired, by this method... I drove a 5 HP 220/240 motor pulleyed to a small 1/4 horse 220/240 single phase motor... Using a drum switch, start the single phase motor... When the speed is up to approx. 1/2 or full speed of the driven 220/240- 3 phase motor, switch the juice off the single phase motor and direct it to the 3-phase motor through the drum switch... Presto, your 3-phase motor will now generate a phase from its 3rd leg... Simply use the 3 HOT legs of the 3-phase motor to run lathes, mills, welders, etc, etc, etc... You can run the driving belt off the pulley of 1/4 HP motor if desired or let it be driven by the 3-phase, 5 HP motor... Bob
 

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

Yes, that's referred to as a Rotary Phase Converter, and the prevalent description is the Fitch-Williams white-paper.

One could drive a three-phase welder from a single phase source by employing a Fitch-Williams, but it's pretty pointless to do so, just for the sake of a welder, if the welder can be internally configured as described above. Reason being, is that the Fitch-Williams utilizes single phase input at 180 degrees, to drive two of the three idler motor's legs (at 120 degree intervals) for purpose of generating third phase suitable for starting other machines. IN the process of doing so, there's substantial limitations, particularly in driving what appear in finality as resistive loads (welding)... and the end result, is that it takes considerably more iron, complexity, and motion to synthesize that third phase, than to reconfigure the transformer core to simply run in a four-quadrant mode, with the center coil being shifted 90 degrees.

I initially test my shop machines, including my welders, on a 10hp RPC I made many years ago... and while it works well for what it does, it simply cannot compete with the performance and integral nature of doing an internal conversion on a welder.

By the way, A CP-300 was successfully converted by a gentleman who read the posts and downloaded writeups from the PM forum. He reported that it's performance is everything expected and more, and he noted that he'd be posting a full step-by-step process fairly soon.
 

poppi

Registered
Re: Running surplus 3-phase welders on single-phase power

just bought Miller Econo Twin HF 60Hz 460 Volt one phase welder.i am told that i can get a one phase transformer rated at 10KVA 208/230 volt to 440/460 volt or vice versa and run it since it is a one phase machine. however looking at attached schematics i believe if i do some changes i will end up with a one phase machine?
AT Schematic 460/575 Volt 60 H z Models with HF
1.remove at L2 between 8/10 PRI T1......S1 and CTI .......18/17.....CB.....
2.remove at L1 between 7/20 PRI T1.......FM.........
3.remove at T1 SOP 25/23 .....CB........W CB......
AT Schematic 208/230 Volt 60 Hz Models with HF
1. add .......CB1....... at L1 and L2........
2. add........FM..........between 9/10 at PRI T1.......
3. .....run 208/230 juice thru L1 and L2 and start burning rod.......
eye..... hope...... eye...... am not off the wall here and agent orange is taking over.........LOL.....
Thanks in Advance
 

Attachments

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

Without opening it up and looking at the 575v transformer primary connections, can't tell. There's a good possibility that they're actually using same transformer for both the 208/230 and 575v, however, they're not indicating anything on this diagram that would support it one way or the other.

If the 575v transformer primary is segmented (meaning, several windings, with interconnections made in series, but not shown in this drawing) then all you'd hafta do, is break that series connection, try to figure out the voltage drops of each segment, and wire them in parallel combination that yields closest to 240. At that point, it'd be plug-and-play.
 

poppi

Registered
Re: Running surplus 3-phase welders on single-phase power

dKamp
thanks
my friend
i will give it a try in the next week or two and eye will keep you posted..........
poppi
 

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

Your method reminds me of this method of operating 3 phase motors on single phase. http://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

Robert
Hi Robert!

That author refers to it as a 'miller system'... more accurately described as Fitch Williams, you'll see that Fitch's rotary phase converter design was published in his white paper long ago... perhaps back in the early '70's and has been in use heavily ever since. Here's a really nice writeup that Fitch did in '98, and posted after he retired back around '04

http://www.practicalmachinist.com/FitchWConverter.pdf

There's some similarities, in the fact that there's two powered phases, and some capacitors, and although it LOOKS similar, that's about where the similarity of operation ends.

A Fitch-Williams converter's function is to generate three phases at 120 degree intervals, using two legs of a three-phase Y connected motor, and the third phase, by nature of capacitive and inductive coupling, yields a 'generated' voltage that acts as the third 120 degree interval. That third leg is a rotating inductor... the starting capacitors will cause enough directional EMF to 'spin up' the motor to it's proper speed, at which point, the single-phase driving current will keep it turning.

The Haas-Kamp conversion doesn't do that... it uses single-phase power to drive a three-phase delta transformer in three-phase sequence, for purpose of generating full magnetic field, and full output on the secondary side of a welding transformer. There is no physically-rotating mass, and it doesn't 'generate' a third phase... it simply creates a figure-8 sequence of magnetic circulation through the transformer core, and uses the phase-shift of capacitors to make the center core segment 'play ball'.

So it would be more like saying soccer and baseball both use one ball... so they're the same. ;-)
 

Mike G

Registered
Last Subscription Date
12/11/2014
Re: Running surplus 3-phase welders on single-phase power

Very cool Dave! Now to find a 3 phase welder cheap......:)
 

Adrielp

Registered
Re: Rewiring Miller MP-30e for single phase power

I maybe able to get a Miller MP-30e for cheap and I am wondering if it can also be rewired to run on a single phase. I believe Mechanically, I have to skill to rewire it myself but I would need to some very good step by step instructions to do that. Either way, if its cheap enough to purchase, I will sell it but I would much rater keep it and avoid the entire barter process if possible. The manual can be found below with the wiring diagram contained within on pg 28. I would appreciate any help in achieving this, thanks.

http://www.millerwelds.com/om/o226e_mil.pdf
 

dkamp

eMail NOT Working
Re: Rewiring Miller MP-30e for single phase power

Hi Adriel-

Yeah, based on the diagram on page 28, looks like it'd work fine... it's a DELTA machine... note there's some jumpers that connect A to B, B to C, and C to A. You'll need to open up the case and look at the terminal strips... find and disconnect those jumpers, then set the voltage selection jumpers to 230v, and connect your incoming lines to coils A and C in reverse phase, then drive the center coil through about a 120uf motor-run cap in each leg. Look at the process for the CP-200 and SRH-333, then take the time to examine your machine, locate all the wires, etc.
 

sandgink

Registered
Re: Running surplus 3-phase welders on single-phase power

Dave,

I have been following this thread and the one on practical Machinist for some time now. My employer has a Miller CP-252TS 3 Phase that they are replacing. I am waiting to see what they want for it. Our welding supplier told them the unit and wire feed together was worth $1300. My question is this. If I can get the price down to some where in the $400 range, can the 252 be converted successfully. I know you have been battling low range performance issues. Attached is the electrical diagram.

thanks

Jake
 

Attachments

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

Hi Jake!

The CP-250TS that I have, operates on single phase, but it doesn't like going into the lower range, because it was never designed for short-arc welding- it only likes spray mode.

Your CP-252TS is substantially newer than the CP250TS, and I suspect that it has been redesigned with additional inductance to allow it to settle down and do short-arc process.

Wiring wise- yes, it'll convert just fine. Looking at the diagram, aside from the adjustable slope inductor, it appears to be very similar to the CP-250 series, so my BET, is that it'll work just fine on single.

That being said, if you're patient and keeping your eyes open, you'll probably stumble upon a CP200 or CP300 for $100... and mebbie even get a used, but serviceable wire feeder for $50...
 

aircrush

Registered
Re: Running surplus 3-phase welders on single-phase power

I just joined this site today & need help.I just bought a old Miller CP-2VS,200 amp mig.I do not have 3 phase service.The welder work's perfect on 3 phase but need to convert to single phase.I took it to Charles Rewind in Dover,Ohio,it is a very good shop but have done little to covert welder's to single phase.Thank's for any help,aircrush
 

dkamp

eMail NOT Working
Re: Running surplus 3-phase welders on single-phase power

I checked:

http://www.millerwelds.com/service/ownersmanuals.php?model

and even searched through the whole list, and I see no listing for a CP-2VS. :shrug:

Please check your machine's serial number, model number, and if it has a 'name', that as well, and find the correct owner's manual for it. If the machine is VERY old, you may have to send the serial number and model to Miller technical support, they'll pull the appropriate document, scan and send it to you in PDF format. Once you have that, we can look at the wiring diagram and transformer design to determine wether or not it's a likely candidate for conversion.
 

aircrush

Registered
Re: Running surplus 3-phase welders on single-phase power

It is a old welder & that is the model number.Here is the serial number.K208010I have pic's but do not know how to post them.Thank's
 
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