The development of vacuum and SF6 distribution switchgear

The nonoil technologies of vacuum and SF₆ have become well established and in so doing have almost completely taken over from oil. The author examines the development of vacuum and SF₆ from their origins and reviews the progress made which has led to the modern designs which offer a long life maintenance free performance. The development of an SF₆ transverse rotating arc circuit breaker is described in some detail together with its further application into outdoor cable connected and overhead line equipment. Details are also given of the special environmental tests carried out on vacuum and SF ₆ switchgear to satisfy the stringent requirements laid down by China Light and Power to cater for the climatic conditions in Hong Kong