Converting 3 phase inverter welder to single phase

Thread Starter

Willnv

Joined Nov 24, 2018
12
I recently purchased a used lincoln power wave 455m inverter welder. The price was right for the machine, I paid $1000 for it and they were originally 10k up. I didn't think to check the input power requirment since all the newer inverters that I've looked at run on 1 or 3 phase. If your not familiar with an inverter welder they rectify the incoming ac to dc then back to high frequency ac in order to reduce the size of transformer required.

Anyways I have turned the machine on from single phase power on 2 of the input legs. It does turn on but I cant test it out yet because all the controls are on a seperate wire feeder that needs to be attached. Being that the first thing the machine does is convert the incoming ac to dc I don't see why it would know/care too much that the incoming power is single phase. The biggest difference I could see is that the dc ripple from 3 phase would be a lot less then that of single phase. So Im thinking of adding some large capacitors to the output of the rectifier to reduce the ripple to at least something close to what 3 phase would have. I have no idea how to calculate this though. Could someone help me figure out what size caps to add. The machine would probably see something like 50 amps max draw on the input.
 

MaxHeadRoom

Joined Jul 18, 2013
19,493
Did you try all combo's of the 3phase for a pair to feed it?
I suspect there could be a single phase transformer in there to obtain the low voltage for control circuitry.
Do you get any indicator lights etc?
Max.
 

Thread Starter

Willnv

Joined Nov 24, 2018
12
I powered it up from single phase 240v connected to l1 and l3. It turns on and gives a green status light. Like I said I can't try it out because I don't have the wire feeder that goes with it and all the controls are on the wire feeder. I suspect it may work at a lower capacity on single phase without doing anything. Maybe the arc would be a bit erratic because of the higher ripple from single phase input. Thats why Im thinking of adding the capacitors.

I also might need to trick the board into thinking its receiving 3 phase. The input lines are tapped with small wires that go to a control board. I think its so it can sense the incoming voltage and so it may complain about the single phase. What Im thinking of doing is removing the sense wires from the supply lines and attaching them to a small/cheap vfd so the machine thinks its getting 3 phase.

Here is the manual for the machine which has the schematic.
 

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MaxHeadRoom

Joined Jul 18, 2013
19,493
The biggest difference I could see is that the dc ripple from 3 phase would be a lot less then that of single phase. So Im thinking of adding some large capacitors to the output of the rectifier to reduce the ripple to at least something close to what 3 phase would have. I have no idea how to calculate this though. .
Could amount to a considerable value, 1phase has 100% ripple 120hz as opposed to 3ph ~5% ripple at 360Hz.
Max.
 

Thread Starter

Willnv

Joined Nov 24, 2018
12
Any idea on a value? I have no idea how to calculate this. Would there be a better way of getting a smoother dc output? The other thing I can think of is using a big rotary phase converter but that would be expensive and not seem very effecient.
 

shortbus

Joined Sep 30, 2009
7,250
The other thing I can think of is using a big rotary phase converter but that would be expensive and not seem very effecient.
Probably why you bought it so cheap. And I'm not to sure welders work with phase convertors, rotary or other wise.
 

Picbuster

Joined Dec 2, 2013
983
I recently purchased a used lincoln power wave 455m inverter welder. The price was right for the machine, I paid $1000 for it and they were originally 10k up. I didn't think to check the input power requirment since all the newer inverters that I've looked at run on 1 or 3 phase. If your not familiar with an inverter welder they rectify the incoming ac to dc then back to high frequency ac in order to reduce the size of transformer required.

Anyways I have turned the machine on from single phase power on 2 of the input legs. It does turn on but I cant test it out yet because all the controls are on a seperate wire feeder that needs to be attached. Being that the first thing the machine does is convert the incoming ac to dc I don't see why it would know/care too much that the incoming power is single phase. The biggest difference I could see is that the dc ripple from 3 phase would be a lot less then that of single phase. So Im thinking of adding some large capacitors to the output of the rectifier to reduce the ripple to at least something close to what 3 phase would have. I have no idea how to calculate this though. Could someone help me figure out what size caps to add. The machine would probably see something like 50 amps max draw on the input.
There is a possibility to do this with a capacitor ( sane way as used by 3 phase motor connected to a one phase line) however; if the welder is not connected in star ( using 3 x 240 plus null) it's in delta that makes it more difficult.
When in star the welder might have an internal strap to select power input format ( see technical manual).
Some welders are using two phases from the 3 available (380-400V) and a strap to use a different power source.

Picbuster
 
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