Yes, that is generally true, especially if the welders don't have high power factor correction. Many generators are not "clean power", which means they emit a sine wave that is not real pure, and has a lot of distortion...more than 10% or by some definitions, 5% from a true wave form. A lot of generators even put out a "modified" sine which is basically a square wave, even though it is relatively clean for the type wave it produces. Another issue is the consistency of the power voltage with the voltage being able to sustain at a constant level if under load or at high rpm. The square wave generators are fine for light bulbs and some electric motors but not electronics. A frequent question I get is why if the welders are square wave, why they can't operate on a square wave generator...which really isn't worth discussing as to why here, but illustrates the point that there is a large variation in generators in general. You can run even the older inverters from Miller on a generator, as long as it is properly matched, and certified by the company that produces the generator with less than 5% total harmonic distortion. We have a similar requirement for our Everlast PA140ST's to be run on a clean genset...which are comparable overall. However, for our new Powertig 210ext's which have a greater than 99% PFC, they are able to handle some distortion and uneven output.
