METHOD AND APPARATUS FOR PRODUCING WELDING POWER

摘要

A method or apparatus for sub arc/tubular wire arc welding includes providing a first wire to a first welding arc and a first ac power signal to the first welding arc. The first ac power signal is a substantially constant voltage signal. A second wire may be provided to a second welding arc near the first welding arc, and a second ac power signal is then provided to the second arc. A phase relationship between the first and second ac power signals is selected from a plurality of at least three possible phase relationships. Preferably the frequency and/or balance of at least one of the signals is selectable. Also, the output frequency is preferably controllable such that it can be more or less than the input frequency.