Power supply for arc welding in inert gas - includes main thyristor rectifier and auxiliary diode rectifier controlled by logic circuits

摘要

The appts. includes a mains transformer (a); a thyristor-rectifier unit (b); a discharge diode (c); a choke coil (d); and a thyristor switch unit (e). Parallel with the high power thyristor-rectifier unit (b) is a low power auxiliary diode unit (f) contg. diodes and resistors. Unit (f) is fed with a reduced voltage from transformer (a) which feeds unit (b), or by a separator transformer (f1). The master switch unit (e) pref. uses nine pairs of logic elements to feed trigger pulses to the six thyristors in the high power unit (b). Alternatively, six logic elements can be used, two on each phase of the 3-phase mains supply. Used for MIG welding, where the appts. provides stepless adjustment of the starting voltage.