Abstract: A welding device for carrying out a TIG welding process, which device enables improved control the welding process. A measuring winding is provided in an ignition device and a second voltage measuring device is provided in the welding device for detecting a measuring winding voltage at the measuring winding; and/or a measuring winding simulation device is provided in the welding device for simulating a virtual measuring winding of the ignition device and for determining a measuring winding voltage at the virtual measuring winding; and a control unit is designed to use the power source voltage and the measuring winding voltage detected by the second voltage measuring device or determined by the measuring winding simulation device to determine a TIG arc voltage at the TIG arc, and is designed to use the determined TIG arc voltage to control the TIG welding process.

Abstract: A power supply unit for a resistance welding apparatus, said power supply unit comprising a converter circuit adapted to convert an alternating power supply current, AC, applied via a residual current protection circuit to an input of said converter circuit into a pulsed electrical current supplied from an output of said converter circuit to a primary coil of a transformer of said resistance welding apparatus, and at least one switching element provided between the output of said converter circuit and protective earth.

Abstract: A power supply unit for a resistance welding apparatus, said power supply unit comprising a converter circuit adapted to convert an alternating power supply current, AC, applied via a residual current protection circuit to an input of said converter circuit into a pulsed electrical current supplied from an output of said converter circuit to a primary coil of a transformer of said resistance welding apparatus, and at least one switching element provided between the output of said converter circuit and protective earth.