What power supply does FCAW typically use?

• A. Direct current (DC) constant current (CC)
• B. Alternating current (AC)
• C. Pulsed DC
• D. Direct current (DC) constant voltage (CV)

Answer: (D)

In FCAW you want the arc length to stay steady as the wire is fed, so the voltage is held constant and the current can vary with the wire feed. A DC constant-voltage (CV) power supply does exactly this: it fixes the arc voltage, while the welding current increases or decreases as you change the wire feed speed and material conditions. This creates a stable arc, predictable penetration, easier arc starting, and consistent bead quality.

Using direct current is standard for FCAW because it provides a stable, unidirectional arc that works well with flux-cored wire. An alternating current supply can reverse the arc and disrupt the flux behavior, making control more difficult. A constant-current supply would keep current fixed and cause the arc length to vary with changes in arc resistance, leading to an unstable arc. Pulsed DC exists in some setups to modulate heat input, but it is not the typical baseline for FCAW.