SANS 61643-21-2009 低压电涌保护器.第21部分:连接到电信及信令网络的电涌保护器.性能要求及试验方法
Low voltage surge protective devices Part 21: Surge protective devices connected to telecommunications and signalling networks - Performance requirements and testing methods
Applicable to devices for surge protection of telecommunications and signalling networks against indirect and direct effects of lightning or other transient overvoltages.