Abstract: The invention comprises a control system for Arc Welding for steady and pulsed direct current welding with a single three-phase bridge converter (1) For steady direct current welding, output DC voltage (V.sub.d) and current (1.sub.d) are varied through the tapping of transformer (2). Finer voltages can be obtained through the variation of firing angles .alpha. of the thyristors of the converter (1). The contemplated control system can also be used for pulsed DC current welding with an impured dynamic response with less effort. The background current, which lies between the maximum and minimum firing angle .alpha. of the thyristors of the converter (1), is set by the transformation ratio of the transformer (2) and the pulsed current is superimposed thereon through the relatively rapid changing of the firing angle .alpha..