Power supply circuit for electric arc welding appts. - for striking DC arcs, and for striking and stabilising AC arcs

摘要

An a.c. supply voltage is fed through a rectifier and a controllable resistor to charge a capacitor (C), which is then discharged by a bridge circuit contg. four thyristors connected in two branches via junctions (a,b). The two junctions (a,b) are joined together by the prim. winding of a pulse transformer; and the sec. winding of the latter is connected to a welding electrode and a workpiece. Trigger pulses for the welding circuits are obtd. from an a.c. supply (Us), which is employed to charge another capacitor (c1). Capacitor (C1) is discharged by a bilateral semiconductor switch (BS) of symmetrical polarity, e.g. a trigger diode. The circuits can be used with either 22O or 380 V a.c. mains supplies, and require only standard components with a low cost.