3 phase welders

A static phase converter will not do a thing for a transformer type 3 phase welder. It might do OK on an old rotary welder. Some one on sci.engr.joining.welding NG tried a rotary phase converter. Seems to me it didn't work as well as expected. I suspect that the inductive load from the welder interacts with the nade up phase from the converter. (Hmmmmm sounds like a GREAT final exam question for a EE major!)
But many of the transformer welders will run OK on 2 phase at 2/3rds power. The output from the transformer goes to a massive diode block, you are just missing one phase. Not as smooth as full 3 phase but decent. You may have to experiment with which phase is dead since there will be fans, control circuits, etc that will be running off a single phase.
Specifics on which make and model you are looking at would be helpful.
Ignoramus15786 wrote:

Thanks.
Miller CP-300 welder.
i

RoyJ sez:
" But many of the transformer welders will run OK on 2 phase at 2/3rds power."
Little problem with your arithmetic, today RoyJ ? Your reply is totally misleading. You should know by now from reading posts on RCM, there is no such thing as 2 phase (generally) available to the home shop machinist.
Bob Swinney
The output from the transformer goes to a massive diode block,

Sure it's single phase but you can put it into a 2 phases of a 3 phase machine. And if you reference it to neutral, you indeed have 2 phases.
Robert Sw> RoyJ sez:

I have run my Airco Pulse Arc 300 (3ph) on my 5hp rotary converter with .35 wire. Worked pretty well, but damn it made the electric meter spin like a dervish. Ive not tried to run it on single phase as I loaned it to a buddy who does have 3 phase in his shop, but will be getting it back soon as his shop has my warehouse attached..and the City is going to turn it into another badly needed abandoned empty lot at the first of the month.
Gunner
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown

If it's wye-connected -- which "reference to neutral" implies, since there is no neutral in a delta connection.
Check the schematic for the welder.

What're we doing here - trolling for Gary?
Bob Swinney

How about answering the OP's question?
Robert Sw> What're we doing here - trolling for Gary?

My experience has been that a transformer machine will work well on a rotary phase convertor, up to the limit of the convertor's ability to produce the third phase.
Older machines without solid state output control (Miller migs with the three big coild with brushes that slide on them) should work well on single phase, as another poster recommended it'll be important to isolate the line that feeds the fan, etc.
John

Thank you, John and others.
i

It depends on the 3 phase welder. New Millers for example are possible of many voltages and phase or legs.
Old versions of 3 phase would likely be best on a rotary I suppose but the other tuned type might work.
Just use a 220V motor to drive a shaft that couples to a shaft of a 3 phase...
Martin

Gunner pretty well answered the OP's question when he stated:
"Specifics on which make and model you are looking at would be helpful."
In other words the original question was so non-specific as to only be answerable in non-specific terms. However, this was no deterrent to some that blurted out "facts" anyway as they hastened to confirm their lack of knowledge on the subject.
Bob Swinney

The item in question is Miller CP-300.
i

thanks... the question is about a MMiller CP-300...
i

Say what? They going to tear it down with nothing going up there?
There's got to be more of a story behind this - the ink isn't even dry on the Supreme Court eminent domain ruling, and CA is supposed to have some pretty strict Eminent Domain restrictions over and above what the Feds just bestowed.
As in, today they wouldn't be able to get away with bulldozing out "blighted" Chavez Ravine for "housing projects" then conveniently have the project fall through right after the Brooklyn Dodgers announce they'd like to move west...
If a municipality already owns the land and building, it isn't in imminent danger of falling down, and they have no use for it, offer them a few bucks of month-to-month rent to leave the building standing.
Even if it's a token rent in exchange for taking care of the place till they come up with a use for it, it's probably more than they'll get for a stupid vacant lot - you can find those just about anywhere.
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Ayup. The very large oilfield shop (complete with 8' radial arm drill, Rockford shaper, 36" x 15' lathes, etc...is owned by one of the local empire builders.
The land is owned by the railroad. The tracks were removed 10 yrs ago, and a bike path put in.
Evidently the owner wants to build some housing elsewhere in town, so the city wants him to remove the building before granting him a permit to build on the other side of town.
I understand that if the renter can come up with $2,000,000 liability insurance per year, he has a chance of keeping the building..but he claims the amount per month will double his rent.
Ive sublet a corner of the machine shop to store machines. The rent is the odd occasional bit of tooling and bits and pieces that I give him. Plus I supplied him with loaner machine tools, so there is no cash out of pocket and is a win win for us both.
He gets tech support, machine tools etc..and I get a decent sized corner of a 140 foot by 60 foot steel building, with 1000 amps of 3 phase, a 10 Ton overhead crane that runs through the building, etc etc.
He is a transmission rebuilder and race car builder. Disabled vet also.
The street that the shop is on, was the main hub of the oilfield warehouse/supply/services part of town. Since the bottom fell out of the oil field in the early 80s..most of the buildings have been torn down, and there is nothing but a half mile of dusty empty lots with a bike path running through it.
So while its not being done under the eminant domain thing..tis being done via blackmail. No permits until the 'eyesore" becomes another dusty empty lot. Its a dying town unfortunately, and the city fathers think it will come back. One of the old builders here claims they are going to turn it into a retirement community. Right..they closed the hospital 5 yrs ago, and the nearest medical services is in Bakersfield...35 miles away. Lots of folks are going to retire here. Ayup. A Kmart, an Ace hardware..and a main street filled with empty storefronts and For Rent signs..that have been up for years.
Gunner, a bit pissed off.
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown

You can buy a new manufactured home, on a foundation on a 2 acre lot, zoned universal, for less than 90k. The average 3 bedroom home, here, on a city lot is less than $100k, and most run $60k.
We have a federal prison, a state prison and a return to custody facility within 10 miles of town, but most of the employees of those places live in Bakersfield, 30 odd miles away, because of the shopping, entertainment and so forth. Its an easy commute.
I love the area, low crime, good schools, very low taxes (for California) and while it tends to be in the 100-107 range during the 4 summer months..its a very dry heat as humitity is quite low.
Gunner
"Considering the events of recent years, the world has a long way to go to regain its credibility and reputation with the US." unknown

Don't be an ignoramus - Oh waitaminit, I've gotta remember who I'm talking to here... ;-P
Go to Go to the 'Service & Support' tab, then the 'Owners Manual' sub-tab, and enter CP-300 in the model box and the serial number in that box, and the exact instruction manual for your welder should pop up in a .pdf file. And you're good to go. ;-)
It wouldn't show me the book for your particular welder because I don't have the serial number. Obviously, when they made mid-year upgrades, they reprinted the manuals to cover them. I looked in my paper catalog, and the current model CP-302 is 3-phase only.
If it's three phase only, that's what the transformers inside need to see - the inverter style units can adapt, transformers can't unless they were designed for both 1ph and 3ph. Static converters are out - they are simply a start capacitor box to get motors going, they won't supply effective running power to the third leg.
A rotary converter will probably work IF you connect the manufactured leg only to the welding transformer - two of the legs go to the control circuits and they'll need to be the two Utility supplied legs. Call or write Miller for details, I'm sure they've been through all this thousands of times...
Hell, I'd just order up a new Big-40 or Trailblazer 302 and be done with it. Just add fuel and go.
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