WELDING APPARATUS

An improved welding power supply includes saturable reactor means in its output to control welding current. A pulse generator is used to control the firing of SCRs which in turn control the average current in the control winding of the reactor and thus the welding current. A unique current sensing circuit provides a feedback voltage to the pulse generator and monitors alternating current, direct current and direct current-reverse polarity welding current without mechanical switching means. The pulse generator is provided with a secondary control circuit which may be used for a limited time to provide higher initial currents to aid in the establishment of the arc. A secondary power supply is also provided which may be connected in parallel with the main power supply to provide a relatively high open circuit voltage to heat the electrode and establish the arc.