The THT 401-501-751 are three-phase professional electronic generators, with separate electronically controlled rod trolley, for use in seam welding (MIG/MAG) and electrode welding (MMA) for acid, basic, stainless steel, aluminium and cellulose. The three-phase power transformer with base current and the SCR arc rectifier are totally controlled, and guarantee continuous controls of the welding parameters and excellent welding even at lower output levels. The THT501 and THT751 versions can also be used for scarfing (ARC-AIR). These are very strong, reliable and easy to use welders. They are ideal for use in medium and heavy metal work, depending on the model, and are particularly suitable for use in shipyards. All the magnetic coils are made from top quality copper and forced ventilation cooled. This gives excellent performance with a 60% work cycle. A temperature probe protects the internal components. The voltage change terminal block inside the machine permits changing the supply voltage. The rod trolley with 4 reels TT4 and 4 reels TP4 (for site work with 5 kg reels) give smooth and constant rod flow, thanks to the control board and the 100W motor installed. On request they may be fitted with digital volt/ammeter. On request, a CW5 gun-cooling unit may be installed. The connection extensions between the machine and rod trolley are available in standard lengths of 4, 10, 25 m. air or water, and 50 m for just air. Special measurements are available on request. The CD-THT remote control permits using the machine as generator for electrode welding (MMA), without the need for the extension or trolley.