Welding Tips and Tricks

Hello,

I'd like to know what is the mathematical relationship between the arc voltage and the arc length?

It becomes also a relationship with where the energy of the electricity is focused. Ohms law is the mathematical formula. It takes volts to jump a gap and make an arc. If you increase the gap it takes more volts. If your on a transformer machine there is a limited amount of volts. If your on an inverter it may sense the needed increase of volts and make changes accordingly. However if you increase volts on a transformer then with its limited adjustments it will decrease amps. (It depends on where your reading the amps) if your talking overall amp draw on the machine or amps applied to the weld arc. The arc length also affects where the energy is focused. This has a relationship with the polarity of the welding process if your talking DC welding. AC transformers would be your most straight forward to calculate. Increase in required voltage would result in a decrease of energy to be registered as amperage. Oscar is a math guy! Wait till he ways in. There’s a few others that can talk joules with you as well.

I'd like to know why you'd like to know. Finals question for you on a test?

In general, the longer your arc length, the higher your arc voltage. After that, "it depends," and a lot of it depends on the Volt-Amp curve for your particular welder, and the slope of that curve in the amperage range you're using it.

See:

https://www.millerwelds.com/resources/a ... g-purposes

for an interesting discussion of "stick machines that can TIG weld" versus "TIG machines that can stick weld" and how their different V-A curves give them different personalities for welding.

An example of one of the consequences of the V-A curve is dig: On machines that have a classic "drooper" V-A curve, the other side of the coin that "amperage decreases with increased arc length" is the opposite: "Amperage increases with decreased arc length." What this means is that as you dig down in a deep root with 6010, the closer you get to snuffing it out, the more amperage and heat you get, which gives the arc a more driving/gouging personality and helps prevent the rod from snuffing out. Typically, inverters need a lot of electronics to give them the "dig" that transformers naturally have simply as a consequence of how they work.

A related discussion that may also be useful is here:

https://books.google.com/books?id=jNxCx ... 22&f=false