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Calibration of Welding Machines

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  • Calibration of Welding Machines

    I am in the business of calibration. Mainly focusing on dimensional and mechanical calibrations. I recently got into some electrical stuff, due to an obvious need for it in the area.
    There are a lot of welding activities and so I went ahead and bought the Miller LBP350, along with a 600A Shunt and a Fluke 8808A.
    I have the procedure outlined by Miller's paper - TechLine "Welding Equipment Meter Calibration", as well as the manual for the Load Bank. I manage to get everything hooked up to where I'm getting corresponding readings on the load bank and the meter..... there is something that I just can't seem to understand though (and pardon my innocence where this is all concerned, I'm just not welding/electrically minded!)....
    When I am hooked up for reading voltage, I get the Open Circuit reading of 80V.... (rated output of the welder is 32V). The procedure says to take readings at 10V intervals from min to max, and I would have thought this would have been done with the load bank switches? How does this work if it's constant current?
    Also, when I'm hooked up (in series with the Shunt) to read amps, the procedure mentions to have the loadbank switched on 100A higher than the max output of the welder. How can I then take the load off (using the breakers) because for a 300A welder as soon as I take the load off to 200A all the breakers trip.
    I'm sure I'm doing something wrong, or totally messing this up, but this is why I'm posting on this forum. I tried looking all over the internet for some better descriptive procedures but I just can't seem to find anything.
    Is there anyone out there that can help me get this part of my business functioning????

  • #2
    For one thing the Load bank (I prefer the Lincoln 750 loadbank) is merely the load point. The gages are pretty much worthless, so I use a Fluke 1010i coupled to a Fluke 87 for amperage and nother Fluke 87 or equvalent for voltage. The are calibrated by an independent lab. As they need to have paperwork behind them.

    Most welding machines can't be truly calibrated anyways as there is nothing to adjust on them..

    Now standalone wirefeeders basically can't be calibrated, nor will they come close to data plate specifications.

    Alot of newer Millers like the Pipworx and such calibrate themselves with a sim card and downloaded Cal software.

    Most newer Lincolns like 350pro, 350mp, and ac/dc subarcs are calibrated through your laptop in conjuction with the above equipment.

    Although, with the exceptions of subarcs and robotic applications, I find calibration is merely a cash cow for the person doing it.

    Best to test the machine to dataplate specifications, if you can't obtain data plate specs to the tune of a 10% error, then the machine has to come in for service,


    • #3
      If the load bank is rated to 350, and I get a welding machine of the same output, yet the procedure says I need to have the breakers on 100A OVER that of the welder.... how does this work?


      • #4
        Do you happen to have a procedure, or know where I can get one - my knowledge is really basic on the electricity side of things!


        • #5
          On say a miller loadbank, they are saying to have a load 100 amps over the Data plates 100% spec. If you set your load bank to 350 amps on a 350 amp welder, It'll never read 350 amps. I'm testing a Vantage 300 right now and I set the load bank to 500 amps. to see if the machine is reading to both 32V @ 300 and Lincolns plus rating of 29V @ 300.

          A basic homemade load bank won't have the stamina of either the Miller or Lincoln version. the hassle with the Miller version is that you can't change the load via the load bank without alot of internal sparks. the Lincoln version has toggled loads via a series of internal contactors. Mind you it was over $5K to buy.

          As for calibration procedures there really arn't any. Thats why I shoot for data plate specs first then dial it down via the machines local control to test the displays in my calibrated meters to the machines. This tells the customer whether or not the machine is working properly, simple testing the displays, means squat.


          • #6
            Thanks Cruizer!!
            Ok- that's kind of what I thought. Wanted to make sure though!!
            What's the deal with voltage readings? Can you take different readings on constant current?


            • #7
              Does anyone know if there's a standard to go by??


              • #8
                Well, I could email you my cert form, just email me at