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Joined: Jul 2001
Posts: 311
An arc welder rated 230V 3Ph.,70A. was transferred from one of our facilities to another. The new location has a building electrical system of 120/208V. 3Ph. 4W.
We would like to spare the expense of boost transformers if possible. Will the 230 volt rated arc welder operate adequately if fed with 208 volts?

[This message has been edited by Frank Cinker (edited 10-02-2004).]

[This message has been edited by Frank Cinker (edited 10-02-2004).]

Joined: Jan 2001
Posts: 1,044
Tom Offline
I've put welders on 120/208 systems several times with no problem. The operator usually has to crank up the amps one or two settings above what he is normally used to using. Since most welding operations do not max out the amps, you should be OK. However, if the users usually run near the top end, you may have to install the transformers..


Few things are harder to put up with than the annoyance of a good example.
Joined: Apr 2002
Posts: 2,527
Generally, where voltage changes over a fixed resistance, power output changes with the square of voltage ratio. So… (200/230)² ≈ (208/240)² ≈ 0.75 or a power-output reduction of 25%.

[This message has been edited by Bjarney (edited 10-03-2004).]

Joined: Oct 2004
Posts: 55
I have never done such a thing but I would expext that it is possible. However you would need insure that the branch circuit was sized sufficently tho handle the additional current. It would not be 125% of 70A and I'm not sure if the calculation would be 125% 77A (230/208*70) or 121A (1.73*70). When you consider the additional power (I sqrd R) loss over time (depending on the amount of use this welder will have) it may be cheaper to buy a boost xfmr.

Joined: Jun 2001
Posts: 161
Almost all of our welders (TIG, MIG, Stick) as well as one of our plasma cutters are made for 230V. We run them at 208 with no problems. More and more you'll find today inverter machines that will accept anything from 208v 1Ø to 480v 3Ø without changing any of the taps. If you have taps for 200v, use those. Lastly, if your machines are CC/CV sources then it really shouldn't matter except on the top end of the machine since they'll compensate for the reduced input by raising their output accordingly.

Mike Wescoatt
Joined: Apr 2002
Posts: 2,527
Mike, thank you for bringing us into the modern world of switchmode power supplies for something besides PCs, like “lunchbox” welders nowadays.

Indeed — "The Auto-Line circuitry automatically connects to 120—460VAC, single- or three-phase power…"

My ancient 60% duty-cycle Airco box has 200-230-460V straps [and old, large but very inefficient selenium rectifiers and a 'mag-amp' saturable reactor for current control.]

[This message has been edited by Bjarney (edited 10-04-2004).]

Joined: Sep 2002
Posts: 931
Likes: 1
Your machine will be around long after the newer equipment is long gone.........

Joined: Jul 2003
Posts: 394
Your's sounds a bit like mine but mine is a big mamma - 100% duty cycle up thru 200 amps, rated over 400 amps on TIG.
These new 'inverter' welders are slick and portable but I don't think and of them will ever run DC as smooth as mine which has a 200 pound inductor in series in the output line. At moderate amps, the welding sounds more like a whoosh that the crackle you always hear about. At about 1000 pounds, it just isn't very portable.

Joined: Apr 2002
Posts: 2,527
Jim, I lied. It's a Linde box {arch comepetior to Airco.}
[Linked Image from]
[Doesn't every guy carry a picture of their welder in their wallet? And nowadays, jpegs on their computer?]

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