Wouldn't have believed if it didn't see it

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Today my buddy had to air_arc out a large deeply beveled weld. We really didn't have a welder up to the task. He hooked together a Bobcat 250 and an old dail arc 250 transformer machine together and crank them up. I know this can be done with 2 like welders would have never tried this. It worked. Both welders survived. Anyone ever try anything like this?Tough as nails and damn near as smart
Reply:If the transformers or generators are not matched you can have a situation where one will "drive" the other.  In the case of generators it can overspeed one engine until it throws a rod.  Most instructions for hooking up machines in parallel is to have matched transformers or generators.  Check some of Lincoln and Miller's operation manuals.
Reply:No I haven't but it should be similar to 2 batteries in parallel. The amps are combined.Leo
Reply:Originally Posted by lotechmanIf the transformers or generators are not matched you can have a situation where one will "drive" the other.  In the case of generators it can overspeed one engine until it throws a rod.  Most instructions for hooking up machines in parallel is to have matched transformers or generators.  Check some of Lincoln and Miller's operation manuals.
Reply:You can't back-drive through a rectifier.  So the problem you'd have like on a DC generator style won't happen.  What will happen is which ever machine has the higher voltage will suffer the greatest load until its voltage droops down to the other machine's voltage.  Then they will both start delivering current.  The one machine may be pegged out constantly, while the other machine just help a little.  With matched machines they should have about the same voltage, and should roughly provide the same amount of current.  Still sounds like a good way to burn something up.What you can't do (without more consideration) is parallel two AC transformers.  If you have them 'out of phase' they will fight each other and burn up.  With two AC engine driven machines you'd have to synchronize the frequency/phase of the AC.  Probably not going to happen with a quick field setup.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:I've seen  a lot of DC welders run parallel in an industrial settings but they were always identical brands and capacity.
Reply:I have operated missmatched DC power supplies (not welders, but simular) in parallel and shared the reletively constant load between them according to their capabilities.  It took a seperate ampmeter on the output of each power supply and careful adjustment of the output voltage controls (an output voltage change of .1 volt made a big difference in way the load was divided between the supplies).I offer three choices: Good, Fast, & Cheap. You may pick two.Hobart AC/DC StikMate LXHarbor Freight AD HoodHarbor Freight Industrial Chop SawDeVilbis 20 Gallon, 5 HP Compressor
Reply:Originally Posted by nadogailI have operated missmatched DC power supplies (not welders, but simular) in parallel and shared the reletively constant load between them according to their capabilities.  It took a seperate ampmeter on the output of each power supply and careful adjustment of the output voltage controls (an output voltage change of .1 volt made a big difference in way the load was divided between the supplies).