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  • Load Bank DIY

    I posted on the welding projects and I now realize that might not be the place for this topic, however after buying many used Miller Welders I started looking at videos of testing, calibration, etc. and I thought about making one myself with capacity similar to the Miller Load Bank 750, but with controls similar to the LBP-350 because a "switch" type control will be easier to procure than the fan style switch. Has anybody made a Load Bank or maybe what might be helpful to me would be some technical manuals for both the 750 and 350 Miller styles and/or the Lincoln Load Master 750. Wondering if it has been done as a new unit is +$5,000.
    Miller Syncrowave 250 DX
    Miller Dynasty 200 DX
    Miller XTM 350 CC/CV Autoline
    Miller Millermatic 252
    Miller Thunderbolt 225 AC/DC
    Miller LMSW-52T
    Miller AlumaPro 25’
    Miller Spoolmatic 30A
    Miller 3045 FC Wirefeeder
    Hypertherm 45XP

  • #2
    The majority of the cost in those banks are in the precision of the meters. I use an oscilloscope with differential probes on the voltage and a hall probe.om the leads. You can use the nichrome coils (dryer/toaster element or coil your own from the wire and hold it with the ceramic standoffs) or do what I did and use two RV water heating elements secured on a single hanger that sits in a big tub of water. You just need to figure out what resistances you want. My RV heaters are each 2500W and 1 ohm resistance, so I run the CV anywhere from 1 to 50V and CC anywhere from 1 to 100a to get up to 5kW output. That is over 100% duty cycle on most inverters run in single phase, except the Thermal Arc 400GTSW (almost had one, missed out on the sale) and the 300 or 350 series Lincoln Invertec/Powerwave. You can get a third heater to go higher, but I think it's overkill from what you want to see. On the opposite side of the coin, you can crowbar your outputs with a 3+ foot of steel to check your CC amperage control from lowest to peak amperage. Your welder has a built in overcurrent protection. This method is actually listed in the Thermal Arc 400 series troubleshooting manual.

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    • #3
      Edit: I think your XMT350 100% duty cycle is higher than 5kW output with a 6/3 power cord, possibly even with the 8/4 power cord that came with it. That's a lot of heat and probably warrants two big tubs...

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      • #4
        Ok thanks, I may try to stay away from the tub of water. I never liked water around my electricity.
        Miller Syncrowave 250 DX
        Miller Dynasty 200 DX
        Miller XTM 350 CC/CV Autoline
        Miller Millermatic 252
        Miller Thunderbolt 225 AC/DC
        Miller LMSW-52T
        Miller AlumaPro 25’
        Miller Spoolmatic 30A
        Miller 3045 FC Wirefeeder
        Hypertherm 45XP

        Comment


        • #5
          If you search load bank in the Miller manual section, you can find the load bank owner's manual (OM-849). The parts breakout give you an idea of the heating coil array they use and the operation portion gives you an idea on the total resistance ranges you should have.
          Hope this helps,
          Jon

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