Abstract: A square wave welding power supply system includes two constant current power sources. The first power source 10 is preferably an SCR controlled power supply having an output connected in an arc circuit 15 through an inverter circuit including SCR-1 through SCR-4 which controls the polarity and duration of the welding current applied to the arc circuit. The second power supply 20 is preferably a reactor power supply for supplying additional welding current during one polarity of the square wave. A shorting means (SCR-5) is connected across the output of the second power supply to maintain current flow therefrom during those intervals when the output of power supply 20 is not connected to the arc circuit. A gating circuit 30 controls the SCRs (SCR-1 through SCR-5) and commutation circuits (C-1 through C-5) connected across each SCR. A diode D1, or SCR, is connected in series with the second power supply output to prevent short circuiting of the arc by SCR-5.

Abstract: A square wave welder includes two regulated constant current power supplies which are alternately connected to a welding electrode. The on time and current of each power supply are independently adjustable. Switching is accomplished by means of gate controlled thyristors, and each power supply is either connected to the electrode or its output is short circuited in order to maintain the current flow at a substantially constant level to improve current regulation.