scope:

This part of the IEC 61643 series is applicable to devices for surge protection against indirect 203 and direct effects of lightning or other transient overvoltages. 204 These devices are intended to be connected to 50/60 Hz AC power circuits and equipment 205 rated up to 1 000 V RMS Performance and safety requirements, tests and ratings are 206 specified in this standard. These devices contain at least one nonlinear component and are 207 intended to limit surge voltages and divert surge currents. 208 The test requirements provided by this standard are based on the assumption that the SPD is 209 connected to an AC power circuit fed by a power source providing a linear voltage-current 210 characteristic. When the SPD is to be connected to a different kind of source or to a different 211 frequency, careful consideration is required. This mainly applies with regard to system and 212 fault conditions to be expected in such a system (e.g. expected short circuit current, TOV213 stresses). 214 This standard can apply for railway applications, when related product standards do not exist 215 for that area or for certain applications. 216 Based on a risk assessment it may not be necessary to apply all requirements of this 217 standard to SPDs designed for specific power applications only, e.g. circuits with a low power 218 capability, circuits supplied by nonlinear sources, circuits with protective separation from the 219 utility supply. 220 NOTE 1: More information on risk assessment is provided in IEC Guide 116. 221 NOTE 2: Other exclusions based on national regulations are possible.