Motor Run Capacitor Dual Head Spot Welder, Capacitor Welding Machine. DESCRIPTION MF DC Inverter Spot Welder is a set of advanced welding equipment. The welding transformer is in small size but the outout energy is large. Three-phase AC will be converted into DC after being rectified. Then the DC will be converted into medium frequency 1000HZ square wave to be connected to primary welding transformer through the inverter circuit which is composed of IGBT. The MF square wave