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  • What size generator

    I have a Hobart 235 ac stickwelder. What is the best size generator for me.

  • #2
    Spec sheet for that welder is here:
    https://www.hobartwelders.com/pdf/sp...mate_LX_AC.pdf

    if you intend to run it at full rated output, multiply the input voltage (230) times current draw ( 47.5 amps) and you get 10,925 watts. You would want something higher than that because you don't run a generator at max all the time. You would need at least a 12KW generator. With that said, will you weld with full power all the time? Not likely. You might also consider buying one of the new inverter Hobart Stickmates (160i or 210i) and a much smaller generator. Flip side of that is your 235 is a rock--not much to ever go wrong and if it does, it's cheap to fix. The inverters have many more expensive parts inside. I recently bought a 160i and love it. Great little machine, so little it almost looks like a toy but it welds great. However, I'm not getting rid of my Thunderbolt (Miller version of your stickmate 235).

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    • #3
      http://www.lincolnelectric.com/en-us...ze-detail.aspx
      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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      • #4
        So even 12 KW isn't enough -- and 1/8 certainly isn't full load. Sounds like you could buy a welder and a gen to run it for less than the gen for that welder.

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        • #5
          people forget that the wall receptacle is just really an extension from a really really big generator at the PoCo That's why the math doesn't work straight across when comparing input amps used between a wall receptacle and a little portable generator-

          They just don't have the mass behind them to absorb the kick in the nuts from the inrush.
          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


          • #6
            Originally posted by Broccoli1 View Post
            people forget that the wall receptacle is just really an extension from a really really big generator at the PoCo That's why the math doesn't work straight across when comparing input amps used between a wall receptacle and a little portable generator-

            They just don't have the mass behind them to absorb the kick in the nuts from the inrush.
            Exactly. Even with only 125A welding current on my inverter stick welder, it will still bring my 7kW generator to it's knees for a split second.

            This one should be fine though.
            HTP Invertig221 D.V. Water-cooled
            Eastwood MIG175 w/spoolgun
            Eastwood Versacut40 Plasma cutter

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            • #7
              Thank you. What you are saying makes sence. Is there a reliable place to get a used generator of that size.

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              • #8
                Have researching the generator requirements to power a classic transformer based and new technology inverter based machine.
                The problem with so called small generators is the output wave form.
                The output is a modified sine wave. Instead of profile that is a perfect sine wave supplied by the utility company, the modified since wave has the tops of the perfect since wave chopped off to a flat profile. When the the voltage reaches the neutral there a slight time delay a zero voltage before the voltage reverses. The delay occurs at zero voltage when the voltage reverses from positive to negative and negative to positive.
                The result makes the already inefficient AC transformer operate at an even lower efficiency, producing more heat from magnetic.

                A review of the specifications for the Lincoln transformer 225AC/125DC reveals the overall efficiency in AC mode at 49% & 38% using utility company power. Would guess the overall efficiency decreases by 50% when small frame generator modified since wave power is supplied.
                This translates to 25% efficiency in AC mode and 17% efficiency in DC mode.

                There is a U Tube video showing a Lincoln 225 AC unit powered by 5500 watt small frame generator burning 1/8" 6011 rod about 2" long bead without tripping the generator circuit breaker. The power output is 60 cycle/sec alterating square wave with time delay at zero voltage.

                Powering the new technology inverter type with the modified sine wave is another issue.
                There welding machines are totally electronic using printed circuit boards.
                The specifications on the Miller Maxstar 161S & Maxstar 210STR mention that not as sensitive to dirty power source.
                The specification on the new Miller Thunder bolt 160 and 210 do not address dirty power.
                Thunderbolt transformer based XL 225AC & 225AC/150DC are no longer being manufacturered.

                Plan on getting a new Harbor Freight 80 Amp DC inverter welding machine , plug in my 7000 watt small frame generator and find out if it will strike an arc. If it does going for the new XL 160 with fingers crossed.

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                • #9
                  Modified sine wave (essentially square wave) outputs are commonly associated with solid state inverters that convert DC Power to AC; do you have some links that show this waveform related to mechanically driven AC generators? I know there are some, usually smaller, " inverter " generators that have an oscillator/amplifier based output, and thus might do a modified sine wave, so maybe that's what you are referring to. In general, a rotating mechanical generator wouldn't seem to me to commonly generate a modified sine wave; would be interested to hear more on this topic.

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                  • #10
                    The specification on most small frame generators state modified sine wave.
                    It is not a true square wave with vertical sides.
                    This type of generator uses brushes on armature to generate AC.

                    Miller technical advised recently that the Bobcat and Trailblazer engine drive welding machines have the armature machined to improve on the output profile over the generic generators like Genrack, Tractor Supply, Harbor Freight, Yamaha. The output is not a pure sine wave like one would believe.

                    Found a U Tube video using a Lincoln 225 AC powered by 5500 watt continuous brush type generator.
                    difficult to start and the arc failed after ten seconds. lincoln was set at 100 amps, looked like 1/8" rod.
                    needed smaller rod or more current.
                    according to my figures the Lincoln could run on ~ 115 amps max secondary draw on 2/10 duty cycle because of inefficiency created by the modified sine wave generator output. With a perfect sine wave from the utility company with lincoln will go up 225 amps.

                    profile of modified sine wave out from brush/armature type generator is easily found online.
                    it is rather disappointing.
                    Last edited by Almond farmer; 12-02-2017, 01:05 PM.

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