What type of power source is required for GTAW?

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

Answer: (B)

GTAW relies on keeping the electrical current steady to control heat input precisely. A constant-current power source maintains a fixed current through the arc, while the voltage automatically adjusts as the arc length changes. This stability is crucial for TIG welding because the tungsten electrode and the shielding gas create a very precise, heat-sensitive arc, and variations in arc length can quickly alter heat if the current isn’t stabilized.

If you used a constant-voltage supply, small changes in arc length would cause large swings in current, making the arc erratic and the weld bead inconsistent. Variable voltage isn’t a standard way to describe the needed control for GTAW, and pulsing describes a mode of current, not a separate power-source type—often a CC machine can pulse the current, but the underlying supply is still constant current.

So the best match is a constant-current power source.