What is the typical power source for TIG welding?

• A. Constant-voltage (CV) machine
• B. Constant-current (CC) machine
• C. Pulsed DC machine
• D. AC only power source

Answer: (B)

Controlling heat input with current is what makes TIG welding precise. A constant-current power source keeps the welding current at a set level even as arc length and arc voltage fluctuate, giving a stable arc, predictable penetration, and a smooth bead—crucial when using a non-consumable tungsten electrode. Using a constant-voltage machine would let current swing with arc length, leading to inconsistent heat and bead quality. Pulsed DC is a mode you can use on a CC machine to modulate heat, but it isn’t the basic power source. An AC-only supply wouldn’t reliably provide the required DC welding current for many TIG applications (though AC is used for aluminum under the right settings). So the typical power source for TIG welding is a constant-current machine.