AC balance is a feature on a lot of ac/dc tig welders that allows the user to tweak the arc to different applications.
AC balance for aluminum welding actually adjusts the percentage of negative and positive current within the Alternating current.
More negative gives more penetration and lets you weld aluminum with a tapered electrode.
more positive gives more cleaning action but also heats up and balls the tip of the electrode.
Miller, Lincoln, and several other manufacturers display AC balance as a number that indicates percent of negative.
for example , a display of 70 would indicate 70% electrode negative….or 70 % of each alternating current cycle is on the negative side.
but other manufacturers display as a percentage of positive …
Still others like the new Everlast 210ext display ac balance is percentage either side of a 50/50 balance where a reading of -30 indicates 30 % + 50% .so a reading of -30 is equivalent to 80% on a Miller or Lincoln. Weird huh?
Its a shame that there is no international standard. But that is the free market place.
Eventually, a manufacturer will devise a simple and intuitive way to display and adjust AC balance.
until then, its important to understand AC balance.
Understand this….if you are working with a new tig inverter that has the AC balance feature for aluminum welding, the electrode will heat up and the point will ball when you add more electrode positive.
This is how you can tell the way the manufacturer designed the machine….so if your electrode is balling, try setting the AC balance in the other direction until you achieve a clean puddle without excessive electrode balling.