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# phase welder on 240 V single phase?

I'm sure this has been asked before, but I searched past posts and couldn't find anything .... I have an old 300 A DC 3 phase welder. It was built to operate on 208 through 440 volts, 3 phase. I was thinking about the whole transformer, rectifier setup which must be the guts of this welder and it seems it should operate, at reduced output on 240 volts single phase with each of the two hot 120 volt inputs connected to 2 of the 3 inputs on the welder, ignoring the third input altogether. What do you folks think? thanks !

John

Reply to
Doctor John
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Reply to
Pat

I think this may work - I found this post on an engineering news group - just no description of how he did it.. I Have An Older Airco [Miller] Mig Welder----------------100% Duty Cycle------And Get Ready For This!! It's 3 phase--------Running On Single Phase!!!! I Looked at The Schematic,And Wired It To What I Thought Should Work.On The Old Miller's Everything Is wired In the Back,You Lift A Flap,And there Is A huge Terminal block For ALL The Connections!! Wich Is the Way All welders Should Be By The Way,And Sure Enough,When I powered it up The Freaking Thing Worked!! Only Thing Is I Lost A Bit Of Control On The Heat, But Otherwise It Works fine! I Use It To Weld Aluminum With A Great Deal Of Sucsess. And I Did This After Everyone Told Me It Can't be Done-----------------ED

Reply to
Doctor John

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My only concern would be overheating/loading if you aren't careful while running it since there are components that are no longer contributing to the load current. Billh

Reply to
billh

You'll have to change the fan motor to a single phase motor. Otherwise it will work. Max output amperage should be held to about 170 amps to prevent overheating the transformer/diodes.

Gary

Reply to
Gary Coffman

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