question for you techinical guys on weld output...

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Something I have always been curious about, and never really sought to find out, but when looking at welders (mainly engine driven)  what's the difference between a machine that produces say 250 amps @ 25 Volts versus one that produces 250 amps @ 28 volts.  I'm just curious how the higher voltage effects weld output at the same amperage?I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Man, that is a good question. I wish I knew too.
Reply:Volts times amps equals the wattage however when you are dealing with an arc gap things change in terms of where that energy ends up.  You know already that long arcs produce more voltage when stick welding.  In answer to your question for the same amperage and two different voltages the arc distance would be different.  Now the question becomes complicated as to how much the heat is going... into the air, into parent metal and into the electrode.  I am sure it is more of a design/engineering question known only by electrical power engineers.
Reply:Originally Posted by Hammack_WeldingSomething I have always been curious about, and never really sought to find out, but when looking at welders (mainly engine driven)  what's the difference between a machine that produces say 250 amps @ 25 Volts 250 X 25 = 6250 wattsversus one that produces 250 amps @ 28 volts.250 X 28 = 7000 watts  I'm just curious how the higher voltage effects weld output at the same amperage?
Reply:Its all in the rating.  Sure 250 amps at 26 volts isn't as powerful as 250 amps at 28 volts.  Just like Tanglediver showed.We stick weld between 27 and 32 volts.  If you look at a HH140, its rated at 140 amps around 14 volts.  It will put out the 140 amps, but not at welding voltage.  This is why I say its how they rate it.When mig welding, the rating means a little different, because mig welding is done up to 23 volts, then its globular or spray in the 26 to 28 volt range.If you take those same #s and figure it out backwards, you will see the amp rating will be different.  With Tangledivers first example, 6,250 watts, AT stick welding voltage, you will get 6250/30 = 208 amps, OR 7,000/30 = 233 amps.I have been welder shopping (again  ) and those #s and duty cycle mean the most to me.I hope I made it sound in print like it comes out of my head.  Edit:  I just checked the Blue and Red machines.  Gas driven Kohler engine. Both the 250 amp model @ 100% duty cycle in CC mode.250 amps @ 25 volts = 6,250 watts250 amps @ 28 volts = 7,000 wattsIN CV mode.275 @ 25 = 6,875 watts.275 @ 28 = 7,700 wattsNOT trying to start anything.  Just too much time on my hands.  David Last edited by David R; 05-13-2008 at 09:51 AM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:I guess its like dropping a bowling ball and a golf ball of a building.  They both fall at the same speed, but one make a bigger impression when it hits.