Combined lightning and surge arresters - spark-gaps or varistors?

摘要

Erich Reuss, of Dehn (UK), discusses the potential problems associated with MOV combined arresters and urges engineers to be aware of the limitations of these devices. According to European Standard EN 61643-11, low-voltage surge protection devices are classified as Types 1, 2, and 3. Nowhere are these discrepancies more obvious than with so-called 'combined arresters', where a multitude of names such as 'combined arrester set', 'Type 1/Type 2 combination', 'B-C arrester', 'T1+T2+T3 arrester' or even 'BCD arrester' are a recipe for confusion, leading to the situation where different products are available with parameters, protective effects and even different wave shapes which deviate from one another.