SF6 decomposition and fault type in SF6 gas insulated equipment

In the presence of arc, partial discharge and thermal discharge, SF6 decomposes into a wide variety of active products which possess different chemical properties. This paper reports on research in SF6 decomposition relating to the ageing- and fault problems of the insulating materials in the gas-insulated equipment. Under the guidance of detection technology, the decomposition mechanism and the decomposed constituent of SF6 are analysed. The qualitative and quantitative determinations of the by-products are studied according to various modes of electrical discharges. In particular, the influence of discharge energies and impurities on the formation of the dominant stable by-products is discussed. According to the characteristic products, the internal fault inside gas insulated switchgear can be determined for fault diagnosis of SF6 equipment.