Control circuits for three-phase welding transformers - using three thyristors connected to the sec. windings

摘要

Welding current source uses phase-splitting to control the voltage and/or the current from a three-phase welding transformer. Three thyristors are located on the sec. side of the transformer, their inlets being connected to the sec. windings which are joined to one pole of the welding circuit, and their outlets are connected to the other pole of the welding circuit. Each of the sec. windings is pref. connected to a bridge rectifier providing single phase current, and a diode and resistor connected in series may be connected in parallel with each thyristor, three embodiments being described together with a control circuit contg. a voltage divider. The welding current voltage can be varied over a wide range.