Patent ID: 7105772

Claim:
An electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path on a workpiece, a first power source for passing a first current with alternate positive and negative pulses between said first electrode and said workpiece, a second power source for passing a second current with alternate positive and negative pulses between said second electrode and said workpiece, a first circuit to generate a first series of polarity changing signals for said first current, a second circuit to generate a second series of polarity changing signals for said second current, a circuit to create a polarity changing command signal in response to each of said polarity changing signals, each of said command signals using a change in polarity only when said current commanded to change polarity decreases to a set value, and a circuit to delay creation of one of said polarity changing command signals after generation of the polarity changing signal that caused said delayed command signal.