Decomposing Mechanism of SF(6) under Positive DC Partial Discharge in the Presence of Trace H(2)O

[Image: see text] The influence of H(2)O on SF(6) decomposition characteristics under positive DC partial discharge (PD) is significant. To evaluate PD fault severity in DC SF(6)-insulated equipment using the production characteristics of SF(6) decomposition components, the corresponding relationship and mathematical expression between the production of SF(6) decomposition components and the H(2)O content should be identified and achieved. Thus, SF(6) decomposition experiments under positive DC PD are performed to reflect the influence of H(2)O on SF(6) decomposition components. Results show that the total discharge quantity and the discharge repetition rate averaged for 1 s decrease slightly when the H(2)O content increases from 0 to 970 ppmv and then increase when the H(2)O content increases from 970 to 5120 ppmv. The effective production rates of SO(2)F(2), SOF(2), and SO(2) increase with the H(2)O content, whereas that of SOF(4) decreases. Finally, the corresponding relationship and mathematical expression between the characteristic ratio (c(SO(2)F(2)) + c(SOF(4)))/(c(SOF(2)) + c(SO(2))) of components and the H(2)O content have been achieved, which can afford references for PD fault diagnosis in DC SF(6) gas-insulated equipment.