Abstract: A power circuit combined with a power circuit control unit includes a single-phase leakage output voltage regulated transformer having a primary winding connected to a power supply and a secondary winding connected to a controlled bridge rectifier. Connected to outputs of the controlled rectifier are a variable resistor, an induction coil with non-linear variable inductance, and an integrator, each being electrically connected to an electrode and to an article being treated. The power circuit control unit acts on the power circuit to permit the welding arc to be fed a current the variation of which can be represented as a sum curve of a direct current component and a periodic curve, having its leading edge rising approximately linearly and its trailing edge falling approximately exponentially.