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Classic AC transformer machine CC

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  • Classic AC transformer machine CC

    Noticed that most AC transformer based machines use a block of metal between the primary and secondary with variable positioning with a threaded rod to vary the constant current output, i.e. Miller thunderbolt XL 225, Forney, Irontron, Vulcan.
    Lincoln AC 225 uses a selector switch with taps from the secondary transformer coil that supposedly selects the constant current output level.

    Can understand why the continuously variable coupler method between primary and secondary works.

    Thought the secondary voltage resulted in ratio of turns between primary and secondary.
    Seems like only the secondary voltage is selected on the Lincoln from the multiple position selector switch and no method to maintain constant current is obtained.

    ​​​​​​How is the secondary current output controlled using the primary selector switch method?

    The LIncoln Idealarc 250 AC\DC (true tombstone) uses the variable transformer core coupling method.


    Last edited by Almond farmer; 12-04-2017, 01:15 PM.

  • #2
    Not much interest in this topic, apparently.
    Researched the two types of AC stick welder transformers.

    The Miller method is to use a variable shut on a threaded rod to adjust the magnetic field coupling between the primary and secondary coils using a magnetic material. With the shut fully engaged between the two coils maximum current is developed and with the shut totally disengaged out the direct path between the primary and secondary , minimum current is developed between the rod end and work.
    With this shut type of transformer the duty cycle increases with decrease in current and vise versa.
    The open circircut voltage remains constant with change in shut position in the transformer core.
    Any shielded arc welder that has a hand crank either on the side or top is the variable shut type transformer.

    The LIncoln type shield arc transformer on the infamous AC 225 incorporates multiple taps on the secondary coil.
    To increase in current the secondary coil is tapped with less windings thereby decreasing the resistance in the secondary circuit to provide addition current. As a result the open circuit voltage is decreased but only by a small amount about 1 volt between coil position selection controlled by the hand operated selector switch. To decrease current the coil is tapped with additional windings with additional resistance in the secondary circuit.
    The current must pass through the selector switch resulting in the same 20% duty cycle for each current selection.

    Apparently , 225 amp AC is the upper limit on the selector switch contacts because the Lincoln Idealarc 250 amp AC\DC uses the variable shut type transformer.

    Comment


    • #3
      AC that's like the AM radio in my car. I haven't used either since the mid 70's...Bob
      Bob Wright

      Spool Gun conversion. How To Do It. Below.
      http://www.millerwelds.com/resources...php?albumid=48

      Comment


      • #4
        I think there are people interested. I simply don't know how to respond.
        I'm into welding with welding machines not into working on or experimenting with welding machines too much.
        I'm way more technical on arc quality and durability and capability.
        Old stick welders/buzz boxes aren't anything I even use anymore.
        I use my Dynasty and the 350P and that pretty much covers it.
        Maybe you should check out welding web for better responses on this stuff. they have a category just for that.


        www.facebook.com/outbackaluminumwelding
        Miller Dynasty 700...OH YEA BABY!!
        MM 350P...PULSE SPRAYIN' MONSTER
        Miller Dynasty 280 with AC independent expansion card
        Miller Dynasty 200 DX "Blue Lightning"

        Miller Bobcat 225 NT (what I began my present Biz with!)
        Miller 30-A Spoolgun
        Miller WC-115-A
        Miller Spectrum 300
        Miller 225 Thunderbolt (my first machine bought new 1980)
        Miller Digital Elite Titanium 9400

        Comment


        • #5
          I like AM radio.

          Comment


          • #6
            Leakage (also referred to as Stray) Transformer basics:

            https://www.youtube.com/watch?v=k5684mQJQRU
            ESAB TIG 252 with Miller CoolMate
            Spectrum 875
            Diversion 180
            Oxy-A (Harris, ESAB, Ox Weld)
            Miller 252
            MM 211
            CST 280
            Trailblazer - Kubota

            http://www.blackdiamondblooms.com/

            Comment


            • #7
              Originally posted by aametalmaster View Post
              AC that's like the AM radio in my car. I haven't used either since the mid 70's...Bob
              WolfMan Jack owes his start to AM Radio --- big honking transmitter (now illegal) they used down in the Desert Southwest.


              Old time transformer tech shines when it comes to longevity -- just look at the number of machines still around and working just like they did on Day 1.
              ESAB TIG 252 with Miller CoolMate
              Spectrum 875
              Diversion 180
              Oxy-A (Harris, ESAB, Ox Weld)
              Miller 252
              MM 211
              CST 280
              Trailblazer - Kubota

              http://www.blackdiamondblooms.com/

              Comment


              • #8
                Originally posted by Crepe Myrtle Farmer View Post

                WolfMan Jack owes his start to AM Radio --- big honking transmitter (now illegal) they used down in the Desert Southwest.
                Comon have a popsicle they are melting all over the place. What movie?...Bob
                Bob Wright

                Spool Gun conversion. How To Do It. Below.
                http://www.millerwelds.com/resources...php?albumid=48

                Comment


                • #9
                  American Graffiti
                  ---Meltedmetal

                  Comment


                  • #10
                    "Hey you think you could spot weld a bumper bracket on my mopar "

                    Comment

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