Which voltage is measured at the output terminals when energized but no welding is being performed?

• A. Arc voltage
• B. Open circuit voltage
• C. Load voltage
• D. None

Answer: (B)

Open-circuit voltage is the voltage you read at the welding output when the machine is energized but no welding current is flowing. This no-load voltage sits there because, with no arc, there’s no current causing drops in the supply. During actual welding, the arc draws current and the voltage across the arc (arc voltage) is typically lower than the open-circuit value. Load voltage refers to the voltage under load when welding is happening, not when nothing is being welded. So the measured voltage in this energized-but-not-welding condition is the open-circuit voltage.