Arc welding current source - with smoothed direct current feeding thyristor bridge for square wave alternating current arc welding

摘要

Welding current source for alternative d.c. welding (heavy metals) and a.c. welding (light metals) uses a rectangular wave form for the latter. This is produced by a bridge circuit, fed by a d.c. source, which includes four thyristors in pairs of two. A firing circuit controls the thyristor pairs which are connected with the anode of one pair to the positive pole and with the cathode of the second pair to the negative pole of the d.c. source. This requires no stabilizing high-frequency pulse generator for igniting the half waves in a.c. welding. A smooth shape of the direct current is combined with a steep zero passage for a.c. welding so that excellent stability is combined with good quality welds in both cases.