Step Up Transformer for Welding Machine

by Gregg

Help -- Step Up Transformer for Welding Machine (CP-300 Miller):

Sir, I have an important question I need answered? I have a 3 phase power supply: 120/208/240 - (200amp box)....... Miller CP-300 wire welder set up to operate at 460v - 575v (30amp.). Can you tell me what size step up transformer I need in order to operate my machine proficiently? And if so do you have one in stock? I am trying to open my own modest welding repair and fabrication shop and that is the only thing preventing me from opening the doors... Anything would be a great help, thanks. GT.

Additional info: L1-120v/L2-120v/L3-213v........actual voltage readings on meter. I don't know what I have other than it's 3 phase. Delta or Wye? All I know is i need to make this work before I go so far in dept that I'm a statistic. I feel safe in saying it is 4-wire...... one being a type of ground.


Comments for Step Up Transformer for Welding Machine

Average Rating starstarstarstar

Click here to add your own comments

Apr 22, 2010

Thanks for posting your own answer! We really appreciate it. :-)

Apr 22, 2010
Power Conversion 3-Phase
by: Gregg

I am answering my own question with hopes that it may help someone else in the future. What I have is commonly known as a (240 Delta with a high leg). L1-120V / L2-120V / L-3-208V. I purchased a refurbished "Square-D" transformer, with a 460v Primary and a 240v Secondary. Through hours of personal research I discovered that the norm seemed to be stepping down more so than stepping up. Any way these transformers will run in reverse. In other words I can take my 240v-D and feed it into the secondary and have 460v-D comming off the primary. So there you have it. New transformer with a KVA rating of 30, which means approximately 30 amps, will cost in the neighborhood of $1500.00 - $2000.00. I got a refurbished with a "new warranty" for $450.00 and the iceing on the cake was that it was close enough to drive and pick it up myself, saving literally hundreds on shipping. These things are full of copper and very heavy. About 380lbs, unless you get one with aluminum windings, which I would rather have the copper myself. So there you have it, I can now run equipment on 460v up to about a 30 amp load and be ok. Hope this helps someone someday. Thanks.

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Advice.