Investigation on SF6 spark decomposition characteristics under different pressures

The decomposition characteristics of SF6 gas-insulated equipment remarkably vary under different working pressures (0.3–0.7 MPa). Thus, the influence of pressure should be considered when adopting decomposed components for spark discharge fault diagnosis. A series of experiments on SF6 spark discharge decomposition under various pressures were performed on the spark discharge simulation experimental platform. The influence of pressure on SF6 spark discharge decomposed components were analyzed quantitatively combined with molecule chemical decomposition mechanisms. Results show that the species of spark decomposed components do not vary under different pressures. However, pressure directly affects the accumulated energy of the electrons in the spark channel, leading to diverse dissociation intensities of electrons on SF6. This phenomenon further affects the rate of neutral-neutral molecule and ion-molecule reactions responsible for the decomposed components. Finally, the yields and effective generation rates of decomposed components CF4, SOF4, SO2F2, SOF2, and SO2 decline with varying degrees under increasing pressure. Moreover, mathematic regression equations were derived for the effective generation rates of the components influenced by pressure.