Abstract: A AC power source for welding is configured to receive three phase power and to provide single phase current to a welding load. The power source includes a three phase transformer with three center tapped secondary windings, a center tapped output inductor, and suitably triggered thyristors between the secondaries and the output inductor.

Abstract: The invention relates to a process and an apparatus for metal arc welding with a consumable electrode. A pulsating current is supplied to the electrode from a constant current source. During the interpulse periods between pulses there flows a minimum current which is at least sufficient to maintain the arc. The switch from pulse current to interpulse current occurs as a function of the arc voltage, with switching to pulse current occurring if a minimum voltage is detected and to interpulse current occurring if a maximum voltage is detected. Compared with conventional metal arc welding with a consumable electrode, this method offers the advantage of a better welding quality.