Decomposing Mechanism of SF₆ under Positive DC Partial Discharge in the Presence of Trace H₂O

Abstract

The influence of H2O on SF6 decomposition characteristics under positive DC partial discharge (PD) is significant. To evaluate PD fault severity in DC SF6-insulated equipment using the production characteristics of SF6 decomposition components, the corresponding relationship and mathematical expression between the production of SF6 decomposition components and the H2O content should be identified and achieved. Thus, SF6 decomposition experiments under positive DC PD are performed to reflect the influence of H2O on SF6 decomposition components. Results show that the total discharge quantity and the discharge repetition rate averaged for 1 s decrease slightly when the H2O content increases from 0 to 970 ppmv and then increase when the H2O content increases from 970 to 5120 ppmv. The effective production rates of SO2F2, SOF2, and SO2 increase with the H2O content, whereas that of SOF4 decreases. Finally, the corresponding relationship and mathematical expression between the characteristic ratio (c­(SO2F2) + c­(SOF4))/(c­(SOF2) + c­(SO2)) of components and the H2O content have been achieved, which can afford references for PD fault diagnosis in DC SF6 gas-insulated equipment.

A DFT Study on Adsorption of SF6 Decomposition Products on Zr-MOF-808

“…During the operation of the equipment, these faults could instigate the decomposition of SF 6 into lower fluorine sulfides (SFn, n = 1-5) [29][30][31]. Given the presence of minute amounts of O 2 and H 2 O, these lower fluorine sulfides could further react to yield SO 2 , SOF 2 , SO 2 F 2 , and other primary products [32][33][34]. Should surface discharges occur in the basin insulator, SFn might produce CF 4 , CS 2 , and the like [35,36].…”

Computational study of the atmospheric oxidation and global warming potential of thionyl fluoride

“…The formation of by‐products in SF 6 has been the subject of extensive experimental and theoretical investigations in various kinds of discharges, that is, power arc, spark, corona or partial discharge [4–12]. Persistent among the observations is the finding that the major by‐products include SOF 2 , SOF 4 , SO 2 F 2 , S 2 F 10 , and so forth, where SOF 2 is always the most abundant stable decomposition product under electrical discharges, formed from hydrolysis of the primary product sulfur tetrafluoride (SF 4 ) [13–16].…”

Theoretical Study on Adsorption Behavior of SF6 Decomposition Components on Mg-MOF-74

“…SF 6 decomposes into extremely unstable low-fluorine sulfides (SF n , n = 1~5) in an overheated environment with long-term failure [1][2][3][4][5]. Although SF n can collide with F atoms in the environment to recover to SF 6 molecules, in the presence of micro-amounts of O 2 and H 2 O, SF n further reacts to form SO 2 , SOF 2 , SO 2 F 2 , H 2 S and other major products [6][7][8]; if the fault occurs on the basin insulator, SF n can react with electrode materials, insulation materials, etc., to generate characteristic gases CF 4 , CS 2 , etc. [9,10]; therefore, the types of the above decomposition products are closely related to the fault types.…”