Numerical analysis on effects of power source characteristics on arc properties in gas tungsten arc

Arc properties in Gas Tungsten Arc (GTA) strongly depend on welding conditions such as an arc current, an arc length and so on. In GTA, the arc current and an arc voltage are determined by an external characteristic of a power source and an electrical characteristic of the arc. There are two kinds of external characteristics of power sources, namely, Constant Current (CC) and Constant Voltage (CV) characteristics. The electrical characteristic of the arc depends on the arc length. In this study, dependences of the arc properties and relationships between the current and the voltage on the arc length in GTA employing power sources with the CC and the CV characteristics were numerically analyzed. As a result, it was found that the voltage and power of the arc decreased with decrease of the arc length in case of the CC characteristic and the current and the power of the arc increase dramatically with decrease of the arc length in case of the CV characteristic. Furthermore, with variation of the arc length, the arc power hardly changes for the CC characteristic, although the arc power largely changes for the CV characteristic.