Very high efficient inverter three-phase synergic power source for MIG/MAG - MMA welding, consisting of a new hardware architecture that fully meets the most stringent requirements in terms of performance and consumption, placed within a robust structure, entirely made of pre-galvanised steel. Separately cooled power electronics: an air flow is forced by the fans inside the cooling tunnel which ensures a perfect division between the exterior and the interior of the power source, thus preventing contamination from metal dust. The yield of this power source is the highest among the comparable ones and allows to obtain a maximum current of 400 A at 100% of the duty cycle (10 min. 40°C), according to IEC 60974-1 standards absorbing about 25 A from the mains power supply