Application for composites to high voltage SF6 switchgear

Porcelain has been traditionally used in high voltage switchgear for mechanical support insulation and as a `weathershed´. This tradition was continued with the evolution of SF₆ circuit breakers some 25 years ago. The choice of weathershed material is influenced by technical and economic considerations. Here, the author describes how the use of EPDM is very common in the USA particularly for lower voltages, whereas the use of silicon rubber is favoured in Europe. Both CIGRE and EPRI have made comparisons. Pollution tests have shown that silicon rubber resists the continuous water film formation on the surface (hydrophobicity) for a much longer time than KPDrt and has low leakage current activity both new and aged