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  • #16
    Originally posted by Broccoli1 View Post
    Your House IS run off 1-leg of 3 -phase
    One or two?

    I think the question is not which is better but what you have to work with? Do you have 3 phase on location? Its not a 120 or 220 volt welder kind of thing. Ether you have 3 phase or you don't.
    Weekend wannab racer with some welders.

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    • #17
      Originally posted by Sberry View Post
      just curious, why the concern with this particular question?
      I work closely with Miller for a living and am just trying to learn the products more in-depth. I've only been on the job a couple of months and try to research all I can...But it comes to a point where having someone tell me information works a lot better than just me reading product specs.

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      • #18
        Originally posted by Vicegrip View Post
        One or two?

        I think the question is not which is better but what you have to work with? Do you have 3 phase on location? Its not a 120 or 220 volt welder kind of thing. Ether you have 3 phase or you don't.
        One- @ 240v which is then SPLIT to achieve the 2 120v Legs feeding the domicile
        Ed Conley
        http://www.screamingbroccoli.net/
        MM252
        MM211
        Passport Plus w/Spool Gun
        TA185
        Miller 125c Plasma 120v
        O/A set
        SO 2020 Bender
        You can call me Bacchus

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        • #19
          Originally posted by Broccoli1 View Post
          Easiest example is with the ol' water analogy

          Filling a Bucket with water with one hose- Single Phase

          Filling a Bucket with 3 hoses- 3-Phase

          The Single Phase Hose would have to be rather large to keep up with the 3- Phase hose
          uhhhhhh, no.
          3 phase power is, how you say, hmmm, more or less constanter than single phase. that's to say that although it's 60 hertz (cycles per second) the three legs are offset by 1/3 of a phase. so instead of turning on and off 120 times per sec., with three phase power it would be 360 times.
          to use your water analogy, it's like having 3 old timey hand well pumps, single phase: one stroke=1 short squirt, return handle, repeat. (three pumps in a line, handles connected, one stroke, one squirt per, 3x volume (or amperage)
          three phase: one stroke=one long squirt. three in-line pumps handles oscilliating (as handle 1 is on the power stroke, handle 3 is on the fill, 2 is on the mid point), continuously feeding agua.

          Originally posted by Broccoli1 View Post
          Now for the Machine side:

          Imagine a Water driven wheel BUT with only one paddle- Single phase
          Same Water driven wheel but with 3 paddles- 3-Phase
          --Both wheels produce 300 amps with each revolution--

          The Single Paddle wheel will need to be constructed quite a bit bigger than the 3 Paddle wheel and the size of the Hoses as well.
          again nope, think of it as your previously mentioned buckets poured on a proper water wheel, single phase: you dump one bucket, the wheel turns a bit, you grab another, dump, turn, so on and so forth.
          three phase: you, Matt & the Sprout continuously pour buckets, brigade style, turn, turn, turn goes the wheel.

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          • #20
            Yeah- I know I left out the On-n-Off squeeezin' part but I did provide the Link that showed dat.



            Hey, I was teaching my new guy how to use a Color Meter the same day
            Ed Conley
            http://www.screamingbroccoli.net/
            MM252
            MM211
            Passport Plus w/Spool Gun
            TA185
            Miller 125c Plasma 120v
            O/A set
            SO 2020 Bender
            You can call me Bacchus

            Comment


            • #21
              Originally posted by Broccoli1 View Post
              One- @ 240v which is then SPLIT to achieve the 2 120v Legs feeding the domicile
              would that not make two 120 V lines in the same phase? Is there a way to take a single phase split it and set one leg 180 deg out of phase with the other? Sarcasim free question by the way.
              Weekend wannab racer with some welders.

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              • #22
                Originally posted by Vicegrip View Post
                would that not make two 120 V lines in the same phase? Is there a way to take a single phase split it and set one leg 180 deg out of phase with the other? Sarcasim free question by the way.
                This does not (in general) make in phase legs. The lines are 180 out of phase, relative to the center tap (grounded conductor, in general, in the US).

                By far the most common method is to have a center tap on the secondary of the transformer that provides 240/120. From the center tap, you see 120V to either end, so, relative to the center tap (which is usually the grounded conductor), you see the two ends 180deg out of phase (when one end is positive relative to the center, the other end is negative)


                Several other ways, as well, most of which involve a transformer. For example, if you have a pair coming in with 240 (such as, for example, in the UK, or in the back corner of an industrial plant where all you have is 240 three phase), a transformer with a single winding and a center tap will give two 120's 180 deg out of phase, relative to the tap. This is an autotransformer configuration, and care must be taken with regard to grounding to avoid a fault.

                A non-transformer method, suitable for low current situation, especially with balanced loads, uses capacitors (one form of 'phase splitter' configuration common in communications), and others use other electronic solutions to generate a center.

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                • #23
                  I'm really suprised that Fishy hasn't given his insight here.
                  Dynasty 350DX
                  Dynasty 200DX TigRunner
                  MM 350P
                  MM Passport Plus
                  Spectrum 375 Extreme
                  08' Trailblazer 302

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                  • #24
                    Maybe it wasnt covered in the semester he took in college....

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                    • #25
                      Originally posted by cliff huxtable View Post
                      Maybe it wasnt covered in the semester he took in college....

                      Uhhhh....beauty college???

                      JTMcC
                      Some days you eat the bear. And some days the bear eats you.

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                      • #26
                        Don't know where he went to school, but he's posted several times how dumb us welders are.

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                        • #27
                          For a welder where you usually want to convert AC to DC a full wave 3-phase bridge rectifier will give you 6 current pulses per 16.67 mSec period (in the US) as opposed to 2 for single phase. This results in a smoother more constant DC.

                          Your house has split phase power or better called a a 3-wire, single-phase, mid-point neutral system.

                          So no to the question above, to get three phase you will need more than one wire.

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                          • #28
                            I never think about this as I jamb a rod in the stinger and I think truth be known, Coke or Pepsi kind of thing most people couldn't tell which machine was which if it was on the other side of the wall. Maybe if they were side by side but from one job to the next? Most people are not that good of welders, and some good welders are not that good.

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                            • #29
                              Well now we're closing in on questions this dumb welder has:

                              Do 3-phase powered welders have smoother or otherwise superior arc characteristics? Can a skilled operator make better welds with them? Iron Head's answer indicates a yes to these questions. Just as a wild guess, I would think the arc would be easier to start and less likely to go out. Can you hear a difference, see a difference?

                              Can they be run off a phase-converter such as you would build in order to run a big industrial lathe in a home shop? Would the superior arc characteristics still be there? Is this worth doing, or are the welding results not enough better to be worth the effort, even for precise work? (Maybe this question is too subjective; I can make many welds with an old Sears buzz-box that are reliable and fully adequate to their purposes.)

                              Do portable engine/generator welders have a 3-phase output? Maybe just some of them?

                              Why, if there is a welding advantage (I'm ignoring the input amp-draw advantage here) to 3-phase for stick and wirefeed welding, as Iron Head indicates, is there not a similar advantage for a 3-phase TIG arc?

                              I have run 3-phase machinery in school long ago, but didn't know enough then (and maybe not now!) to detect differences that would be obvious to skilled welders. I suppose at my age I'm not going to do any critical pipeline work or nuclear, but I've wondered about 3-phase anyway, and appreciate any enlightenment, as always.

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                              • #30
                                You will notice a difference in the arc between a single-phase and 3-phase machine, all else being equal. This difference goes away with the inverter machines.

                                SOME welder/generators have three-phase output. The Miller Trailblazer has two alternators, one for single-phase auxiliary power and another for three-phase welding power.

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