Patent ID: 7105773

Claim:
An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece, said welder comprising a first electrode driven by a first wire feeder toward a point in said groove, a second electrode driven by a second wire feeder toward said point and a main power source with a first output terminal connected to said first electrode and a second output terminal connected both to said second electrode and directly or indirectly to said metal workpiece to create a second electrode path and a workpiece path, said power source including a high speed switching output stage for creating current with a selected AC waveform between said first and second output terminals, said waveform of said main power source having an independently adjustable frequency unrelated to a line frequency of line voltage provided to the main power source and said waveform being generated by a waveform generator controlling a pulse width modulator circuit to determine the current operation of said output stage and a device for moving said electrodes in unison along said groove in a given direction.