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  • #16
    Originally posted by ryanjones2150 View Post
    My little maxstar 150 STH is dual voltage and the best it will do on 115v a 3/32 7018, but it actually does good on that rod. It’s also only 100amps max on the lower voltage. That would probably be a good machine for an experiment like this. Turn the amperage down to 100 when it’s plugged into 230v and fire away.
    If it actually runs good then theres no reason it would not be as strong as the same weld done on any other machine. A stick welding machine is really not much more then a glorified transformer. Somebody could make a welding machine that has 300 amps output on a 120 volt input. But they never would because it would take a breaker of double the size and they input wires would also be double the size. It just makes no sense. Voltage is the king of moving power
    www.silvercreekwelding.com

    Miller Trailblazer 325 efi
    Miller extreme 12vs
    Thermal arc 186 ac/dc
    Lincoln power wave 455m/stt with 10m dual feeder

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    • #17
      One other thing. The length / size of wire running to these little 110v or dual voltage machine has a pretty big effect on how they run. Plugged into an outlet close to the pannel vs 200 feet of cheap 16 gauge extension cord. Close to the outlet and it probably runs that 3/32 7018 pretty decent. Plug it into that 200 foot cord and you probably wont even be able to get the arc started.
      www.silvercreekwelding.com

      Miller Trailblazer 325 efi
      Miller extreme 12vs
      Thermal arc 186 ac/dc
      Lincoln power wave 455m/stt with 10m dual feeder

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      • #18
        Makes good sense to me, Willvis.

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        • #19
          Originally posted by ryanjones2150 View Post
          Every welding machine manual I’ve ever seen has a volt/amp curve chart. Check yours, you’ll see it. It certainly makes more sense when you see it graphed out, I’m with you there.
          Right on, Ryan. And lots of other good comments in this thread.

          I've been busier than the proverbial one-armed paper hanger for the past couple of months, but just had to toss in my two cents on this one. Many of you guys know all this stuff, but hope this helps someone.

          The 120/240 input power (or even the 460/480 range) voltage is all about convenience (not many of us have 480 available in our shops, and some don't have 240) and cost. I am going to dramatically oversimplify this, because there are a lot of equations about transformer design, efficiency, power loss, etc. that are behind this question, but here's my attempt at a hopefully relatively simple answer. The weld output needs X amps at Y volts to melt the rod and penetrate the base metal. There is a lot to be said about how much of each has what impact on the weld, but as I said, this is a simplified description. Volts x amps = watts. So, let's say you're burning a rod at 150 amps at around 30 volts. That's 4,500 watts. Now, the puddle doesn't care if that 4,500 watts comes from a 120 volt or 240 volt source, so long as the design of the welder can pump it out. (But, with the 120 volt machines I know of, you'd probably never get 150 amps out of one. One could be designed to do it, but I don't know of anyone who sells one that will --would cost too much to make and no one would buy it). Anyway, you could be feeding that thing with 25,000 squirrels running in their little cages, so long as they are producing that 4,500 watts steadily and reliably without allowing the voltage or current to ever bog down. Now, the question is, how do you design the welder to effectively put 4.5KW (for our example) into the puddle? You could hook up a gasoline or diesel engine that has enough horsepower and torque to not get dragged down by the generator when you strike the arc. In fact, if you're anywhere but the US (and maybe Canada, I don't know), a lot of engines are rated in KW rather than HP now. If you don't want all that noise, (and don't want to have to feed and water the squirrels), then maybe plugging it in to the power line is better.

          So, someone designs a welding machine to plug into 120 volts. It will need a transformer to step that 120 down to 30 volts. (In real life, they use much higher voltages on those small machines, to get enough power.) For purposes of discussion, we will say the transformer is 100% efficient. (they aren't. If you put 1,000 watts in the input, you may only get 900 or so out of the secondary winding; the rest goes into heating your shop. With our 4.5KW example, and a perfect transformer, how much current would we have to draw from the power line? Well, 4500 watts divided by 120 volts, says you would be pulling 37.5 amps from the power line--and drawing it through the primary winding of the transformer. Here's where the cost comes in. Besides the power being transferred to the secondary (and through the rectifiers and out to the puddle), there is also power lost due to heating of the wires that make up the transformer, and that power is calculated by squaring the current and multiplying times the resistance of the wire. At relatively low currents, this isn't too big a deal, but as the weld current goes up, the transformers get bigger (and thus require larger wire to get the current through). Knowing that copper wire (and aluminum, for that matter) isn't cheap, you want to design for the lowest current in the transformer windings you can, and still get the required watts out of the secondary, because higher currents demand bigger wire. (Just an aside--aluminum wire is a pretty fair conductor, but nowhere near as good as copper, and since it heats up more, its resistance goes up and down more as you weld, meaning you may need a ditch box to keep tweaking the current as the aluminum changes temperature. And since it isn't as good at conducting as copper, you have to use bigger wire for a given amperage, which makes the generator or transformer bigger...). Back on topic...The kicker is that the power lost in the transformer increases as the square of the current; double the current, and you generate four times as much loss as heat, never to be recovered except for heating the shop. Thus, it becomes immediately obvious why you want to use as high a voltage as you can, and still satisfy your target market. If you use lower input voltage, you have to have higher currents, which means you have to use bigger, more expensive wire to make the transformers, and you generate a lot of heat. If you use a higher voltage at the stinger, you can have a shock hazard and the lawyers get after you...lots of design compromises to be considered. On the other hand, if all you made was 240 or 480 volt welders, there are a lot of people who wouldn't buy one, but those who had the power infrastructure to run them would only be drawing a fraction of the current. So, in a well-designed welder, the input voltage should not make a big difference, all else being equal--just be sure you're putting out the kilowatts with no bogging down. Now, practically, there is a lot more to it. A 120 volt welder just isn't going to have the chutzpah that a 240 volt one will, just due to the simple limitation of available input power; half as much, essentially, at a given current draw. That said, when I run my Dynasty200 on 120v, it will burn 3/32 rod very nicely. At 1/8, it will burn it, but it probably won't make you happy. On 240, it runs 1/8 or 5/32 like any other 200 amp machine. Slagslapper noted the difference on arc starts. For sure! The reason is at arc start, there is a huge surge for a number of milliseconds, and at that moment, a 120 unit is going to bog down (remember that current squared thing?) Huge pulse of heat in the transformer, (not to mention inductive reactance--more involved topic) caused by energy that never gets to the puddle. And, as Willvis notes, you can measure this stuff yourself in relatively 'steady state' welding--you just can't measure the surges at arc start unless you invest many thousands of bucks in fancy test equipment.

          This could go on and on, with lots of math, but I hope it helps. Never did get into duty cycle; obviously, the faster the welder heats up, the shorter the duty cycle. So, once again, higher input voltage = less current= less heating = better duty cycle.

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          • #20
            Welcome back, Wayne!

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            • #21
              A great write up but that I dont think some of that stuff applies as much on an inverter machine. They are using much much smaller transformers due to the fact that they are inverters. Esentially changing the incoming ac to dc and then pulsing it at very high frequrncy in order to reduce the transformer size. So then its just the input wires and breaker that need to be bigger for the lower voltage

              Anyways to answer the OPs question with the right machine and running a rod that it can handle (3/32) 120 or 240v input it doesn't make a difference as long as the rod is running good.
              www.silvercreekwelding.com

              Miller Trailblazer 325 efi
              Miller extreme 12vs
              Thermal arc 186 ac/dc
              Lincoln power wave 455m/stt with 10m dual feeder

              Comment


              • #22
                Originally posted by Willvis View Post
                A great write up but that I dont think some of that stuff applies as much on an inverter machine. They are using much much smaller transformers due to the fact that they are inverters. Esentially changing the incoming ac to dc and then pulsing it at very high frequrncy in order to reduce the transformer size. So then its just the input wires and breaker that need to be bigger for the lower voltage

                Anyways to answer the OPs question with the right machine and running a rod that it can handle (3/32) 120 or 240v input it doesn't make a difference as long as the rod is running good.

                Thanks for the catch; agree completely--I should have stated that. I was talking transformer (old, like me) machines. The transformers are still needed, but as you say, they are really tiny since the inverters run their oscillators at much higher frequencies. I fix old oscilloscopes (or will be getting back into it more as the winter wears on, I hope), and transformers that used to be half the size of a toaster and weigh 20 pounds are now so light you can hardly tell they're in your hand, and a couple of them will fit in my coffee cup!

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                • #23
                  Originally posted by ryanjones2150 View Post
                  Welcome back, Wayne!
                  For a bit. Life has been crazy! Check PM.

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                  • #24
                    Originally posted by ryanjones2150 View Post
                    Ha! Don’t be brother. You know the guys I’m talking about, you’re another one of the good ones holding on through tough times. Fortunately our know-nothings aren’t participating either.
                    I'd like to participate but I know nothing lol
                    Dynasty 400 wireless
                    Coolmate 3.5
                    Sw320 speedway
                    Ck flex lock 230
                    4 victor flow meters
                    2 Flametech Duel flowmeters
                    2 genuine miller torch buttons
                    A$$ loads of tungsten
                    XMT 350 CC/CV
                    S74DX feeder
                    Stick leads from here to China
                    A30 Spool gun
                    WC24
                    Langmuir crossfire hobby table
                    Everlast powerplasma 100 w hypertherm torch
                    Harris O/A
                    Pet raccoon
                    I'm just a peckerwood in the boonies with fancy welding equipment

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                    • #25
                      Man I wouldn’t say “nothing”. Now maybe next to nothing, but not quite nothing.

                      I’m only kidding. Don’t sic the raccoon on me.

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                      • #26
                        Power is what does the work of welding. To find out how much power in watts you have, multiply your volts times amps. If the power is the same, then each have the potential to be equal. But since 110V sockets providing greater than 20A service are pretty rare, (and you probably won't find a 110V welder that could use more,) you are limited to 2200 watts with 110V. But a 220V outlet can usually provide at least 20A in a residential setting and as much as 50A in that same setting. So, you will have anywhere from 4400W to 11000W available with a 220V welder at home. In an industrial setting it would be even more.

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