The invention relates to an energy supply system for a mobile resistance welding machine for flash-butt welding of track rails, comprising a combustion engine (1) coupled to a generator (2) as well as a charging device (5) for charging an energy store (7), wherein the energy store (7) is a buffer element of an intermediate circuit (13) to which a welding inverter (14) is connected. In this, the energy supply system comprises an island grid to which the generator (2) is connected and which is coupled to the intermediate circuit (13) by a controlled power converter (16).

The invention relates to an energy supply system for a mobile resistance welding machine for flash-butt welding of track rails, comprising a combustion engine (1) coupled to a generator (2) as well as a charging device (5) for charging an energy store (7), wherein the energy store (7) is a buffer element of an intermediate circuit (13) to which a welding inverter (14) is connected. In this, the energy supply system comprises an island grid to which the generator (2) is connected and which is coupled to the intermediate circuit (13) by means of a controlled power converter (16).

A flash welding machine welds together a first metal product's tail with a second metal product's head. The machine includes a carriage, a first structure with a first grip, a second structure slidingly supported by the carriage with a second grip. The power group includes an inverter, a transformer, a rectifier, a control unit operating the inverter at frequencies greater than 700 Hz, and conductors connected to the first and second grips. The transformer delivers predetermined nominal power at a predetermined nominal supply frequency. The predetermined nominal power is less than the predetermined operating power and the nominal supply frequency is less than 700 Hz. At frequencies greater than 700 HZ, actual power equal to/greater than predetermined operating power, or the predetermined nominal power of the transformer is at least equal to predetermined operating power and nominal supply frequency is greater than 700 Hz, with actual power greater than predetermined operating power.