Partial Discharge Decomposition Characteristics of SF6/N2 Gas Mixtures under Insulator Air Gap Defects and Free Metal Particle Defects

The use of $\mathrm{SF}_{6} / \mathrm{N}_{2}$ gas mixtures in gas-insulated equipment reduces the greenhouse effect of pure sulfur hexafluoride gas. In this paper, the partial discharge decomposition of $\mathrm{SF}_{6} / \mathrm{N}_{2}$ gas mixtures under insulator air gap defects and free metal particle defects is investigated. The results show that the main decomposition products of $\mathrm{SF}_{6} / \mathrm{N}_{2}$ gas mixture under insulator air gap defects and free metal particle defects are $\mathrm{SO}_{2} \mathrm{~F}_{2}, \mathrm{SOF}_{2}, \mathrm{SO}_{2}$, nitrogen dioxide, nitrogen trifluoride and carbon tetrafluoride in insulator air gap defects $\mathrm{SO}_{2}, \mathrm{NO}_{2}$ and NF
3
maintain a good linear relationship, and these decomposition products can well characterize the magnitude of discharge, and then characterize the equipment internal intensity of localized discharges. Under the free metal particle defects, the rms gas production rates of SOF
2
and $\mathrm{SO}_{2} \mathrm{~F}_{2}$ basically show a linear increase with the increase of discharge, and the rms gas production rates of NO
2
and NF
3
basically show a saturated state.