Design of Metal-Oxide Surge Arresters

Metal oxide surge arresters protect electric power systems from overvoltages. The conventional design of metal oxide surge arresters includes a stack of metal oxide varistors and a housing, either a porcelain hollow core insulator or a polymer hollow compound insulator. However, the progress in the polymer technology makes designs possible which are simpler and more cost effective. As an alternative to the use of a polymer compound housing, the active part of the arrester may be kept together by fibre reinforced plastic material wrapped onto it or by a cage of fibre reinforced plastic rods. Among the different polymer material for the housing of wrapped and cage design surge arresters, silicone rubber shows the best ageing and pollution behaviour. Cage design surge arresters with silicone rubber housing offer cost effectiveness, high mechanical resistance, safe burning and short circuit behaviour and excellent long term ageing properties. They are typically used as medium voltage surge arresters, substation surge arresters up to 300 kV and line surge arresters up to the highest voltage levels. 1