Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 14 of 14
  1. #1
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default Converting a 3 phase welder to single phase ....

    This is a topic I have been researching for a little while and thought it might be of interest to others.

    There is a method out there, dubbed the "Haas-Kamp" conversion method, that allows a 3 phase welder to be used on a single phase supply, to almost it's full potential. It involves rewiring the transformer primary and adding a couple of capacitors to try and emulate the phase shift seen with 3 phase.

    So recently I got hold of an old 3 phase Uni-Mig 350 (an Australia made welder, fancy that ) and have done a "proof of concept" conversion. Low and behold it works.

    The basis of the conversion is as follows:
    1. Convert the 415V star configured primary to 240V delta. NOTE: For this conversion to work in Australia, you will need to have a welder that is configured 415V star. If is is configured as 415V delta you are out of luck
    2. Wire the first transformer primary straight, the third in reverse (180º out of phase) and connect the middle one to the other two via two capacitors (which will give you something approaching 90º phase shift).
    3. Ensure any accessories (fans, contactors, etc) are running off 240V. This was the case with the Uni-Mig, so nothing to do here.
    4. As the secondary OCV was a little depressed, I also changed the transformer secondard from a delta configuration to star configuration.


    Here are the before and after circuit diagrams (note that the after diagram does not show the change to the secondary).
    Attached Images Attached Images
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  2. #2
    Join Date
    Feb 2009
    Location
    moonbi nsw Aus
    Age
    69
    Posts
    364

    Default

    Hey Vern
    you are getting into the realm of grass skirt and bone through the nose while dancing in a trance around a sacred fire.
    Was the conversion difficult to do?
    Just do it!

    Kind regards Rod

  3. #3
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Quote Originally Posted by chambezio View Post
    Was the conversion difficult to do?
    Hey Rod. Nah is was pretty easy.
    The hardest thing was figuring out the switching configuration for the welding voltage switch. It switches between taps on the primary side of the transformers to change the output voltage. The circuit diagram did not show any of that information.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  4. #4
    Join Date
    Feb 2009
    Location
    moonbi nsw Aus
    Age
    69
    Posts
    364

    Default

    Your tenacity comes to the again. You won't let anything beat you!!!
    You will be pleased to know the drum sander is making forward progress, albeit spasmodic.
    Have you got in mind a project for this welder???
    Just do it!

    Kind regards Rod

  5. #5
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Quote Originally Posted by chambezio View Post
    You will be pleased to know the drum sander is making forward progress, albeit spasmodic.
    Yes, good to hear. Let me know if you need a hand with anything.
    Quote Originally Posted by chambezio View Post
    Have you got in mind a project for this welder???
    I actually needed it last week to weld up a cattle grid, however I ended up connecting my old transformer TIG power supply through my small Kemppi MIG (being used as just a wire feeder), but that is a whole different story.

    I have been looking for a beefy MIG for a while but couldn't find a single phase one in my price bracket. So no immediate need, but it will get used. Still need to tidy it up a little.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  6. #6
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Interesting conversion - do you still get 28V on the output of the aux transformer?

    On a slightly related note, I've always wanted to see how the secondary was wound/wired on a 3 phase AC welder.

  7. #7
    Join Date
    Aug 2003
    Location
    Conder, ACT
    Age
    77
    Posts
    2,803

    Default

    DISCLAIMER

    No liability is accepted by UBeaut or the Wood Working Forum's administrators
    or moderators for advice offered by members posting replies
    or asking questions regarding electrical work.
    We strongly advise contacting a Licensed Tradeperson for all electrical work.
    WARNING

    Information supplied within posts is not to be considered as detailed formal instructions to complete a task.
    Members following such information do so at their own risk

  8. #8
    Join Date
    May 2008
    Location
    Perth
    Posts
    241

    Default

    Interesting!

    How's the duty cycle? And does the 240v lead get warm at all?

  9. #9
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Quote Originally Posted by RustyArc View Post
    Interesting conversion - do you still get 28V on the output of the aux transformer?
    If you look at the circuit diagrams you will see that the aux transformer has both a 415 and 240 (marked 380 and 220) tap on the primary ... I simply moved one of the wires from the 415 tap to the 240 tap and hey presto we still get 28V on the secondary.

    Quote Originally Posted by RustyArc View Post
    On a slightly related note, I've always wanted to see how the secondary was wound/wired on a 3 phase AC welder.
    I'll grab some pics today, if I can.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  10. #10
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Quote Originally Posted by LordBug View Post
    How's the duty cycle?
    The duty cycle shouldn't really change, as I'm still using all transformers in a "3 phase like" configuration.


    Quote Originally Posted by LordBug View Post
    And does the 240v lead get warm at all?
    That would depend on what current you are welding at. In the little bit of welding I have done so far I have not noticed any heating, but I haven't really done much, only testing at this stage. Running off a single phase will mean that more than likely I will be limited by the circuit feeding welder (in my case a standard 15A circuit). Having said that I could always use a 20A or 32A single phase connection, or a hard wired dedicated circuit, but I doubt I will ever want to use this welder at it's full capacity (it is rated at up to 400A ).
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  11. #11
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Quote Originally Posted by Vernonv View Post
    If you look at the circuit diagrams you will see that the aux transformer has both a 415 and 240 (marked 380 and 220) tap on the primary
    Yup, I was thinking that tap was just an autotransformer output to get a 240 supply, but I guess it would work just as well in reverse.

    I'll grab some pics today, if I can.
    I actually meant a 3 phase AC *stick* welder - I've never understood how you get an AC output from that kind of welder.

  12. #12
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Quote Originally Posted by RustyArc View Post
    I actually meant a 3 phase AC *stick* welder - I've never understood how you get an AC output from that kind of welder.
    Oh, I see, sorry. I don't know, I've never really thought about it.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  13. #13
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    Here are some photo's of the welder after conversion. You can see the primary side of the transformer (the photo with all the wiring in it) as well as the secondary side (not as much wiring). Still waiting on the right size caps to come in before I can finish it off - I will mount them on the inside back wall of the case.
    Attached Images Attached Images
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  14. #14
    Join Date
    Oct 2006
    Location
    Armidale NSW
    Age
    52
    Posts
    915

    Default

    The new capacitors arrived yesterday, so fitted them last night.
    Have done a little welding with it over the past few weeks and I must say that it operates perfectly on single phase. So far I've welded 1.5, 3 and 5mm mild steel and have been very, very happy with the results.


    Attached Images Attached Images
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •