FCAW and GMAW use _______ power sources because they are ideal for semi-automatic processes.

• A. Constant voltage
• B. Constant current
• C. Pulsed current
• D. Alternating current

Answer: (A)

Constant voltage power sources keep the arc voltage around a set value while the current varies with the wire feed. In FCAW and GMAW, the operator mainly controls how fast the wire is fed, not the voltage. So as you push the trigger and the wire current rises, the heat increases, but the arc length stays relatively stable because the voltage is held steady. This makes the arc easier to control and the weld bead more consistent in semi-automatic work. Other power modes would require you to manage voltage more directly or don’t provide the same stable arc behavior for automatic wire feeding, which is why constant voltage is the preferred choice.