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3 phase inverter on single phase

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  • 3 phase inverter on single phase

    I'm wondering if anyone has any experience with running a 3 phase inverter machine on single phase. Specifically the machine I want to run is a lincoln 455m/stt(I know, miller forum... Lol) I picked one up for pretty cheap, didn't really think to check out the phase requirment. Honestly I thought at the time all the inverter machines could run on single phase. All the ones I looked at in the past could run on single phase, I guess I never looked at anything this big.

    The machine does power up on l1 and l3 connected to single phase. I can connect the power wave software, even updated the firmware. The manual mentions reduced output on single phase which leads me to believe it will run, however one lincoln rep I talked to said probably not. I dont have the feeder that is required to test it, all controls are on the feeder. Really the first thing the machine does is run the input into a bridge rectifier so I dont really see why it wouldnt work. Only reason I can see is that the input lines are taped with small wires to a control board so it could complain when it sees single phase. I could probably remove those lines from the input and run them off a cheap/small vfd to trick the machine into thinking its getting 3 phase.

    Anyways so I have a few options.
    1. Try and sell it as is and buy a single phase machine. Could be a hard sell without a feeder or proving it works.
    2. Buy a used feeder(if I can find one) and sell it. Hopefully turn a small profit.
    3. Buy a used feeder and try and run it on single phase. Its like almost a 600 amp machine so even if I can get half the output its probably good for me. I just wanted something the can do pulsed mig.
    4. Say screw it. Take a risk on a new feeder and try run it as is. Worst case scenario maybe I would need a phase converter.

    I guess Im leaning towards try to find a good used feeder then try and run it.

  • #2
    It will power up the power supplies but you need 3 phase for the weld output. No getting around it. Many times I've had a 3 phase machine come in and a customer complaint is it powers up but won't weld. Works fine here to find out the customer lost a leg. 3 phase are tough to sell because mostly factories need them and most don't do private transactions.

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    • #3
      That's one of the reasons Id like to make it work if possible. I still feel as though its going to have output even on single phase. Why would the write in the manual (it also comes up as a code) that weld output is reduced. You would think they would write that there is no output on single phase if that were the case. I wish there was a way to test it without the feeder.

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      • #4
        So there is an option in the computer software to turn the output on for load banking the welder (for calibration). If I used a resistive load of some sort on the output stud at least that could tell me the load it should pull right? I have a 5500w heating element in a still I made. If I took the ohm rating x voltage the machine is putting out I can use ohms law to figure out the amperage. So then in the software I set the machine output to that amperage? What happens when I raise or lower the amperage from what the load should be pulling?

        At least this will tell me if it will output something on single phase. I guess it wont tell me anything about quality of the arc though.

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        • #5
          I wouldn't even mess with it at all on just single phase. Who knows why they stated that phrase in the manual as they did.
          I can understand you bumming out because you paid for a machine without checking into it far enough, but beating your head against the wall will only make it worse!! You are gonna loose money here plain and simple. Stop the bleeding now. BTDT and bought the T shirt
          If you buy a phase converter it's still gonna be somewhat marginal. Inverters are finicky and can even be fickle. If you screw it up are you gonna pay to fix a machine you can't even use? It sounds like it's made for running very thick steel.
          I vote to get rid of it for whatever you can get and lick your wounds now. You only make this mistake once.

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          • #6
            I didn't see anything in the manual about running it on single phase. I have seen this listed in other manuals though for other 3 phase machines. There was a comment in the manual about "max rating 325 if you lose a phase".

            "A single phase input (loss of L2) will reduce the secondary current limit from 570 Amps to 325 Amps." That kinda implies you can run it without L2.

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            • #7
              I read the same thing. It does throw an error code when I power it up under single phase and run the software. But even under the possible solutions it says if single phase is intentional to make sure your procedure doesn't exceed the reduced current of single phase.

              It all kind of implies it would run on single phase. Realistically the first thing it does is run the line power through a rectifier. It would be dc past that point wether incoming power is single or three phase. Only difference would be single phase is going to have alot more ripple on the dc. I could smooth it out with some big capacitors.

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              • #8
                FusionKing,

                I hear what your saying and a part of me agrees. However I think selling a 3 phase power source that doesn't "do" anything is going to be really hard to sell. At least if I found a feeder for a reasonable price and it doesn't work out I can sell it as a package and any one with a shop that has 3 phase might be interested.

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                • #9
                  I would talk with someone that sells phase converters.............as I've seen some interesting things done with large 3 phase stationary 10 HP elec motors being used as a single leg converter.......work well in a friends shop that had several CNC 4 axis mills.........Inverter welder don't know?

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                  • #10
                    Originally posted by Willvis View Post

                    It all kind of implies it would run on single phase. Realistically the first thing it does is run the line power through a rectifier. It would be dc past that point wether incoming power is single or three phase. Only difference would be single phase is going to have alot more ripple on the dc. I could smooth it out with some big capacitors.
                    They were specific about L2 so I'd experiment with hooking the 220 to the 2 other phases. Like you, I think it's just a matter of ripple. It depends on how good their filter caps are on the output of the rectifier.

                    You know 220 is really 2 120 volt wires that give you 220 between them. When you hook up 220 like this to a 3 phase welder, doesn't that mean the output of the rectifier is 120 DC instead of 220 dc?

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                    • #11
                      It has to be connected to l1 and l3 for sure. It wouldnt turn on otherwise. Ive been posting about the filter caps on an electronic forum and I think I found some that will work. They are huge and a bit expensive but would still be worth it.

                      I was wondering the same thing as you about the rectified voltage. Everything online seems to indicate it would have an output of 340vdc. Im going to put the volt meter on the rectifier and see what it reads. Also in the software it tells you the voltage of 2 capacitors and they say they are at 360v dc.

                      Ok now for the confusing part that Ive been wondering about. On 3 phase your line to line voltage reads 208v rms but it is still 120v line to neutral. On single phase(split phase) its is 240v. The 208v reading has to do with the 120* out of phase nature of 3 phase. Therefore I think the peak voltages of the 2 would be the same. The peak voltage is what you end up with when you rectify the ac and add the filter caps. So on the machine there is a jumper wire to select 208v input of 240v input. The question then is what to put the jumper wire on. My gut tells me it should be on the 208v setting. Anyways thats probably just a matter of trying both settings and seeing what works. I dont think its gonna damage the machine either way.

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