SF6 Partial Discharge Decomposition Characteristics Under Different Lengths of Wire-Type Metal Particles in Direct Current Gas Insulated Equipment

Aiming at the serious defects of wire-type free metal particles, which can cause severe partial discharge (PD) in Direct current (DC) gas-insulated equipment, the experiments on the influence of four lengths (3.0, 5.0, 7.0, and 9.0 mm) of wire-type free metal materials on SF 6 decomposition under DC PD were conducted. The formation rules of four characteristic decomposition components, namely, CF 4 , SOF 2 , SO 2 F 2 and SO 2 , under different lengths of wire-type free metal particles, were determined using gas chromatography. Results showed that the amounts of four kinds of SF 6 DC PD characteristic decomposition components are proportional to the length of wire-type free metal particles. The long length of wire-type free metal particles increases the intensity of PD and the amount and effective generation rates of SF 6 DC PD characteristic decomposition components. All these findings provide an experimental basis for the diagnosis of insulation defect types in SF 6 DC gas insulated equipment.