IEC 61643-11:2025 is applicable to devices for surge protection against indirect and direct effects of lightning or other transient overvoltages. These devices are intended to be connected to AC power circuits and equipment rated up to 1 000 V RMS, the preferred frequencies taken into account in this document are 50/60 Hz. Other frequencies are not excluded. Performance and safety requirements, tests and ratings are specified in this document. These devices contain at least one nonlinear component and are intended to limit surge voltages and divert surge currents. The test requirements provided by this document are based on the assumption that the SPD is connected to an AC power circuit fed by a power source providing a linear voltage-current characteristic. When the SPD is to be connected to a different kind of source or to a different frequency, careful consideration is required. This mainly applies with regard to system and fault conditions to be expected in such a system (e.g. expe
