Asymmetric AC Pulse

  1. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    Hi! :)

    That's independent AC?
    Can you mean something else?
    Asymmetric is different current amplitude on DC+ and DC- I think. Like 40A DC+ and 20A DC-. Alternating. AC.
    There can be a pulse but that's not asymmetric if the pulse is between 100-70A. First one or several waves with 100A DC+ and 100A DC-. Then one or several waves with 70A DC+ and 70A DC-. That isn't asymmetric I think. That's just a pulse.
    I'm reading about walter acdc tigs and the manual doesn't say anything about it although their brochures are saying asymmetric AC pulse.
    No luck contacting them.

    Best regards
     
  2. Seadog

    Seadog Forum Supporter

    Messages:
    4,085
    Location:
    NE London - UK
    Alternating dc+ and DC- is akin to ac. Does it perhaps mean pulses of DC of different pulse widths?
     
  3. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    Thanks @Seadog! :)

    I think DC+ and DC- alternating is AC.
    They have something they call AC double pulse but that looks like just pulsing AC.
    Nothing asymmetric about it.
     
  4. 1fingerBET

    1fingerBET Member

    Messages:
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    Location:
    Sweden
    Also they have a acdc mix in two versions.
    AC followed by DC-. And AC followed by DC+.
     
  5. Seadog

    Seadog Forum Supporter

    Messages:
    4,085
    Location:
    NE London - UK
    It sounds like BS to me. But what do I know? :D
     
  6. 1fingerBET

    1fingerBET Member

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    28
    Location:
    Sweden
    I really would like to know. :)

    Bad wibes when they don't answer emails.
     
  7. Richard.

    Richard. Member

    Messages:
    17,814
    Location:
    Cambridgeshire
    It’s not BS it’s a real thing.
    Iirc it’s something miller started off on the higher amperage dynasty range.

    So you get AC balance let’s say 60% dc neg and 40% dc pos.
    both take place at a fixed current at say 100 amps.

    You can use a pulse and set say 50 on the back ground and 150 on the main but a pulse is still a totally independent system to the AC balance. You do not have any control over where the background current is in relation to where the AC cycle is.

    Asymmetric Ac welding combines the two things to work together. So you can set a balance of 30% dc positive with a current of 50amps and the 70% dc negative at 150amps.

    Why???
    Very nice feature indeed imo.
    Balance is a compromise
    Too much neg and you lack cleaning
    Too much pos and you lack penetration and wreck tungstens.

    You can over come this and make each half of the cycle more useful than before by adding lots of current to the negative side and reduce the negative%
    Then take current away from the positive side and increase the positive %

    In theory its a big step closer to been able to weld with deep pen, lots of cleaning and keep the tungsten pointed without using helium doped gases.
    I’m yet to try it out but if it works like I think it should then it’s brilliant.
     
    Hopefuldave and eLuSiVeMiTe like this.
  8. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    Welding tips and tricks talks about it.
    "Aluminium bike welding with Mike Zanconato"
     
  9. 1fingerBET

    1fingerBET Member

    Messages:
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    Location:
    Sweden
    And I don't think he means that independent AC is BS.
    I think he talks about the manual and brochures. About the asymmetric claim.
    But what do I know? :)
     
  10. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    Anyway, Walter is in business. My mails was filtered as spam they think. :)
    They apologized and are planning to give me an answer.
    The topic was
    Can asymmetric AC pulse be something else than independent AC?
     
  11. Seadog

    Seadog Forum Supporter

    Messages:
    4,085
    Location:
    NE London - UK

    Richard, I'm struggling to make sense of this. Is it terminology that's causing the issue here or my complete lack of understanding of the setup? You're using dc +ve and dc -ve in the same sentence as ac balance. If we're talking ac, then I would refer to the positive and negative going parts of the cycle. Is this what you are referring to as the dc pos and dc neg?
     
  12. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    DC+ and DC- alternating is AC.
    Positive volt and negative volt.
     
  13. DTS Member

    Messages:
    157
    Location:
    Rugby
  14. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    What weco is calling extra fusion is independent AC. They also have a acdc mix ending with DC-.
     
  15. DTS Member

    Messages:
    157
    Location:
    Rugby
    Asymmetric over one cycle then, or is there another definition of asymmetric?
     
  16. Seadog

    Seadog Forum Supporter

    Messages:
    4,085
    Location:
    NE London - UK
    Thanks for that DTS. That makes it clearer. All that's happening is that an offset is applied with respect to zero volts (the return lead) and the ac is pulsed for a set period and then held negative for a further set period.
     
  17. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    I am mot sure. Guess you can call several things asymmetric. Like a balance that isn't 50/50.
    But I think that asymmetric ac is when you can set DC+ to 100A and DC- to 140A and alternate between them. Alernating current. AC.
    Independently set AC.
     
  18. Richard.

    Richard. Member

    Messages:
    17,814
    Location:
    Cambridgeshire
    Yes in a nutshell that’s what it is.
    Not particularly difficult to understand.
    The polarity is fluctuating at your set frequency and the time you set in each side of the polarity is your balance.

    Asymmetric despite what people want to say it should and shouldn’t mean, in AC tig welding terms means you can assign a current to the half wave so that not only the polarity changes but the current changes with it.
    Top half being DC +
    Bottom half being DC -
     
  19. 1fingerBET

    1fingerBET Member

    Messages:
    28
    Location:
    Sweden
    I was wrong about the weco discovery machines.
    They don't have independent AC.
    What they call extra fusion is an increase of DC- from 0%(DC+ and DC- is equal) to 80%(DC+ stays the same and DC- is 80% higher than at 0%).
     
  20. brockenhammer Member

    Messages:
    156
    Location:
    Freiburg, Germany
    Stel should have it at the 221.

     
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