SkillsUSA District Welding Practice Test

GMAW welding relies on a constant-voltage power source. Keeping the arc voltage steady as the wire is fed in allows the arc length to stay consistent, which gives a stable arc and uniform bead as you vary welding conditions. The wire feed speed mainly controls the current, so you can adjust heat by changing feed rate while the voltage remains steady. If the power source were constant current, the voltage would have to swing with changes in arc length, leading to an unstable arc and erratic welds. Pulsed and AC options exist in some specialized setups, but for typical GMAW, a constant-voltage supply is the standard choice.