SF 6 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 SF6 decomposition under DC PD were conducted. The formation rules of four characteristic decomposition components, namely, CF4, SOF2, SO2F2 and SO2, under different lengths of wire-type free metal particles, were determined using gas chromatography. Results showed that the amounts of four kinds of SF6 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 SF6 DC PD characteristic decomposition components. All these findings provide an experimental basis for the diagnosis of insulation defect types in SF6 DC gas insulated equipment.