Trending of SF6 decomposition by-products characteristics under artificially induced PD in GIS

Abstract

This work aims to study the decomposition of Sulfur Hexafluoride (SF6) and describe the energy of partial discharge (PD). It is also aimed to identify feature or key gases generated under the activity of discharge induced by artificially introduced insulation defects. Different configurations of four types of defects were used in the discharge chamber, and the analysis of decomposition components were employed to detect the PD. The variation of decomposition by-products along the stress duration under different levels of PD energy were studied, and key gases generated under each type of defect have been proposed. A series of experiments have been conducted using experimental platform including testing equipment, discharge chamber and PD measurement equipment. The applied voltage was gradually increased beyond the PD inception voltage after each sampling throughout the energisation duration to study the correlation of discharge energy with concentration and amount of generated products. Decomposition by-products, detected using Fourier transform infrared spectroscopy (FTIR), have been analyzed to reveal the relationship with the energy of PD. Results have shown that products such as SO2F2, SOF2, CO2 and C3F8 were generated by some defect configurations at different rates, and sulfur-containing products are more stable and correlated with the PD level. Analyses of the characteristics of decomposition by-products can be used to effectively assess the condition of SF6 gas insulated equipment (GIE).