I sold my inverter machine to buy a three phase arc welding machine because I read it's more solid, but I can't figure out how to wire it, the seller is clueless he doesn't know what is the difference between three phase and single phase, the manual is in Chinese with bad translation to English and for a different model; I returned it to the seller, and I tried to find another one but I couldn't find any three phase AC arc welder there are only single phase welders so I bought it back from the same seller again. The model is BX1-250 "BX1 Series" it has two inputs "1" for 240V and "2" 380V. I think I should connect N-L1 in input 1 and L2-L3 in input 2, but I'm afraid I'm going to toast it. Anyone is familiar with these AC ARC welding Machines?

  • My English is not good.


  • That looks like a single phase welder. Are there any pictures in the manual? There may be some here who can read chinese.
    – Jasen
    Jan 25, 2021 at 18:31
  • Not in Chinese, it's like Google translator from Chinese to English. So this is a single phase after all.
    – David
    Jan 25, 2021 at 18:39
  • Do you actually need a welder that takes three phase power, or do you just need one compatible with your three phase power supply? I'm guessing the seller thought you meant the latter, and sold you a single phase welder which is compatible with your power supply, by using two of the three phases. Also, where in the world are you, and what power do you have available exactly?
    – Nate S.
    Jan 25, 2021 at 19:06
  • 1
    @David, so then why do you need it to draw lower amps? I'm trying to figure out what problem you're actually trying to solve by moving to three phase power, since you can get just as powerful welders designed for single phase as you can for three phase (unless you're talking absolutely huge). And single phase welders are going to be far more widely available since they can be used on either single or three phase power, whereas a three phase unit would require three phase power which most people don't have.
    – Nate S.
    Jan 25, 2021 at 19:29
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    I don't think we can help you without more information. You've given no details about the welder - the only identifier you've given turns up what's obviously a different unit. And you've given no details about what power is available to you in your locale. Jan 25, 2021 at 20:05

1 Answer 1


It depends how you count phases. from looking at the back my guess is that you either connect 240V single phase to the 240V terminals or a 380V supply to the 380V terminals.

I'm guessing that the welder has a single phase transformer inside it.

380V is what you get across two phases of some 3 phase supplies (where they use wye with 220V to a central neutral)

240V is a common 3 phase voltage in USA, but 240V single phase is also used.

Connecting to both sides seems wrong as there is a lot of metal between the terminals, and all conductors in a circuit should always pass through a single hole in the metal, also a welder doesn't need a neutral connection.

  • It seems to be a single phase arc welder it has 2 + 2 cores.
    – David
    Jan 25, 2021 at 19:10
  • 2+2? I have not investigated the construction of moving iron welding transformers in detail.
    – Jasen
    Jan 25, 2021 at 19:14
  • I just noticed that it's an AC arc welder, the only welders that use all three phases are DC welders.
    – Jasen
    Jan 27, 2021 at 3:02

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