IEC 61643-21 Ed. 1.0 b:2000, Low voltage surge protective devices - Part 21: Surge protective devices connected to telecommunications and signalling ... Performance requirements and testing methods

Is applicable to devices for surge protection of telecommunications and signalling networks against indirect and direct effects of lithning or other transient overvoltages. The purpose of these SPDs is to protect modern electronic equipment connected to telecommunications and signalling networks with nominal system voltags up to 1 000 V (r.m.s.) a.c. and 1 500 V d.c.