DISPOSITIF POUR STABILISER ET ALLUMER UN ARC DE SOUDAGE ELECTRIQUE A L'AIDE D'IMPULSIONS D'ALLUMAGE

Welding arc stabilizing and igniting is effected with at least one pulse-forming condenser switched by spark gap or semiconductor switch to deliver a sharp discharge pulse through the winding of a pulse transformer, the magnetic energy thus built up in the transformer being then dissipated by a unidirectional diode bypass of the winding through the switch. The pulses are delivered by the transformer to the welding electrodes, and can be combined with pulses of lower voltage and longer duration by an appropriate series condenser-resistor combination in the transformer output. The pulse-forming condenser can be charged by simple resistor connection to the input of a step-down welding current transformer, or by transformer coupling to any source of AC welding current. Trigger means can also be connected as by transformer coupling for operation from the welding current to trigger the pulse discharge switching at the appropriate times in the current waves, although the triggering can be effected through the use of voltage-dependent pulse switching and the charging of the pulse forming condensers to voltages at least as high as that needed to actuate the switching. The switching means can also be protected by a blocking condenser in series in the output of a pulse-forming condenser, and the blocking condenser can be bridged by a resistor to bleed off the charge developed in the blocking condenser by a discharge pulse.