Connect 2 - 110V welders in series across 220VAC?

Not enough information - however -

If the two welding machines are electrically similar and isolation transformers, not autotransformers, then probably yes...

If you get the phase of the inputs or outputs wrong when you try to connect them, your 'parallel' connection will be a series short circuit.. if they hum loudly and the room lights dim when connected, you did it wrong...

The Lincoln tombstone or Miller Thunderbolt 225 amp buzz boxes are cheap and reliable - probably less trouble and $$$ than the two 110 volt machines and ready to go 'out of the box'

Carla

Carla,

I have a Merlin 150 that I picked up for about $30.

For a 110V welder, this brand is top drawer.

If I could get another for the same price, and I could parallel them, not only would I have the capacity of the Miller or Lincoln, I would also have the portability of a lightweight pair of 110 welders, I could use them in places where 220V is not convenient.

You could use 2 - 110VAC receptacles from different breakers. A 'parallel' receptacle box could be built for a few bucks to make the parallel connections a plug-it-in operation. You could store them on a shelf and save scarce shop floor space.

Is there a multimeter test to determine if the transformers are isolation?

Thanks for your valuable input.

Boyntonstu

With the meter on ohms, measure from one of the primary leads to one of the secondary leads. The reading should be infinite or extremely high (over 100K ohms). If the reading is low (less than around a 100 ohms) then the primary and secondary are connected and is likely an autotransformer.

If you should do this then if you have to be careful which circuits you plug it into. If you use 2 110V circuits that are "in phase in the North America system" and wire the secondaries appropriately and the next time plug it into 2 110V circuits that are "out of phase" the secondaries will be wrong.

I am not a big fan of running transformer secondaries in parallel because there is too much chance for a high circulating current if they aren't well matched. Since the welders are a CC device this problem may be lessened (?).

Billh

If you connect their ground clamps together and separate their electrode clamps you could put a voltmeter across the electrode clamps and when you plug both of them in and turn them on any voltage you can measure is an indication of how mismatched the outputs are. I don't know how much would be acceptable, maybe only a volt or so, but if its many then you have a problem.

If the welder is electronic type - e.g. the controls that controls the current - It likely would not work but one never really knows on complex servo systems in parallel.

Pure transformer type welders with step down low voltage, high current likely. It is very risky if not the exact model since the phasing can be out by 180 degrees and you would not have an output but a great amount of current flow from one machine to another.

To test this condition, I'd put a #16 gage wire or less - or better - if you have one - a fuse of say 20 amps - in each leg of welders. At least 2 maybe 4ea. If there isn't a problem the fuses won't blow. They will protect the boxes from a bad hookup. Then and only then can they be hooked up in high current use.

This is the way the power companies connect parallel windings and motor types connect windings of unknown motors.

Martin