What type of power source is proper for GTAW?

• A. Constant Current
• B. Constant Voltage
• C. Pulsed Current
• D. Variable Frequency

Answer: (A)

GTAW requires a stable arc and controlled heat input, which is best achieved with a constant-current power source. By keeping the current set value steady, the welder can maintain a consistent arc even as the arc length changes slightly during weaving or filler addition; the machine automatically adjusts voltage to hold that current, giving predictable penetration and weld quality.

Using a constant-voltage source would keep voltage fixed, causing current to swing as the arc length changes, leading to an unstable arc and difficult heat control. Pulsed current is commonly used as a mode to manage heat input, especially on thin materials or when trying to limit distortion, but it’s a mode of operation on a current-source unit rather than a different fundamental power-source type. Variable frequency is not a separate power-source type for GTAW; it’s a parameter used with AC TIG, not the baseline means of delivering power.