Negative DC partial discharge decomposition characteristics of SF6 under different gas pressure initiated by needle-plate insulation defect

Summary

To study the correlation between the internal partial discharge(PD) of Negative DC gas insulated system and pressure, SF6 PD decomposition characteristics experiment research under different pressures were carried out based on constructing SF6 decomposition experiment platform. Firstly, the 96h experimental data of decomposition components SOF2, SO2F2, CO2, SO2 and CF4 under different pressures was obtained by the stainless steel needle-electrode defect. Then the characteristics component content and its ratio along with the change of pressures were analysed in detail. The study show that SF6 decomposed components content will decrease as the pressure increases. The concentrations of SO2F2 and SOF2 are much larger than the other three gases, which are the main decomposition products of SF6 under DC PD. What ‘s more, the effective characteristic ratio of SO2F2/(SOF2+SO2) and CF4/CO2 gradually decreases with the increase of gas pressure and its modification of the pressure effect is needed, when GIS is used for fault diagnosis. The effective characteristic ratio of (CF4+CO2)/(SO2F2+SOF2+ SO2) gradually increases with the increase of gas pressure and reaches the stability after 0.3MPa. Therefore, when the GIS is used for fault diagnosis whose gas pressure is in range of 0.3MPa ~ 0.4MPa, the effect of gas pressure on the effective characteristic ratio of (CF4+CO2)/(SO2F2+SOF2+ SO2) can be neglected.

Additional informations

Authors

D. YANG, J. TANG, Q. YAO, Y. MIAO, F. ZENG

Keywords

SF6, Partial discharge, Decomposition component, DC, Gas pressure