Three phase controlled power supply for a direct current arc welding system

Claim 1

IN AN ARC WELDING SYSTEM FOR SUPPLYING A DIRECT CURRENT TO A WELDING ARC STRUCK BETWEEN A PAIR OF SPACED ELECTRODE MEANS, A POLYPHASE TRANSFORMER HAVING A PLURALITY OF SECONDARY PHASE WINDINGS AND HAVING CONTROL SOURCE WINDINGS WOUND ONE IN COMMON WITH EACH PHASE WINDING, A PLURALITY OF RECTIFYING MEANS CONNECTED ONE EACH IN SERIES WITH EACH PHASE WINDING AND DEFINING A PAIR OF DIRECT CURRENT OUTPUT TERMINALS FOR CONNECTION TO THE ELECTRODE MEANS, SAID RECTIFYING MEANS BEING NORMALLY NONCONDUCTING AND HAVING AN EXTERNAL FIRING TERMINAL FOR RECEIVING AN INPUT SIGNAL AND EFFECTIVE TO CAUSE THE RECTIFYING MEANS TO BE CONDUCTIVE, FIRING MEANS HAVING A STORAGE MEANS AND A DISCHARGE CIRCUIT INCLUDING THE FIRING TERMINAL AND A CHARGING RATE CONTROL MEANS TO CAUSE SAID RECTIFYING MEANS TO FIRE AT A SELECTED POSITION IN A HALF CYCLE OF ALTERNATING SECONDARY WINDING VOLTAGES, A RECTIFYING MEANS CONNECTED TO THE CONTROL SOURCE WINDINGS AND THE STORAGE MEANS FOR CHARGING THEREOF TO A PRESELECTED VALUE AND DISCHARGING THROUGH SAID DISCHARGE CIRCUIT, AND ADJUSTABLE CONTROL MEANS CONNECTED TO THE CHARGING RATE CONTROL MEANS TO PRESET THE FIRING POSITION IN EACH HALF CYCLE.