Investigation on the formation reactions of SOF<inf>4</inf> and SO<inf>2</inf>F<inf>2</inf> under electric discharges

Abstract

The analysis technique of main SF 6 decomposition products (etc. SOF 4 and SO 2 F 2 ) is expected to compensate for the ultra-high frequency (UHF) method in partial discharge (PD) diagnosis and insulation condition monitoring of power equipment. SOF 4 and SO 2 F 2 as well as other corrosive byproducts derived from the reactions of SF 6 dissociation species (e.g., SF 2 , SF 3 and SF 4 ) with the trace impurities of H 2 O and O 2 under electric discharges. But the formation processes of SOF 4 and SO 2 F 2 are still not clear, which are closely related to the evaluation of PD type and energy, making the analysis method of SF 6 decomposition products in PD diagnosis a lack of theoretical supports. For this reason, this paper is devoted to investigating the formation reactions of SOF 4 and SO 2 F 2 under electric discharges. The possible formation reactions of SOF 4 and SO 2 F 2 are studied by quantum chemistry calculations with density functional theory (DFT). Then the rate constants of these chemical reactions are calculated in a large temperature range 300 – 12 000 K by transition state theory (TST) with Wigner's tunneling effect correction. This work lays a basis for better understanding of the analysis approach of key SF 6 decomposition products in electric discharge diagnosis and insulation condition monitoring of power equipment.