Correlation characteristics between DC partial discharge quantity and SF 6 decomposition components under the needle-plate electrode

In order to study the relationship between SF 6 gas decomposition components and the strength of PD caused by the metal protrusions defect inside the DC gas insulated electrical equipment, the DC SF 6 PD decomposition experiment was carried out for 96h under different discharge quantity in this paper, using the needle plate electrode to simulate the metal protrusion defect. The DC PD quantity was detected by the pulse current method. The paper obtained the growth regularity of SF 6 decomposition components under different DC PD quantity. The results show that the stable decomposition components of SF 6 under the negative DC PD include CF 4 , CO 2 , SO 2 F 2 , SOF 2 , SO 2 and so on. The generation amount relationship between the five gas compositions is CF 4 2 2 2 F 2 2 . SO 2 F 2 and SOF 2 are the main decomposition products of SF 6 under DC PD, the content of which is much higher than the other three. The DC PD quantity affects the concentration of these products significantly. The concentration of CO 2 , SO 2 F 2 , SOF 2 correlates well with Q sec . The concentration of these components increases continuously with the discharge time under the different Q sec . The generation speed γ m of SO 2 F 2 , SOF 2 and (SO 2 F 2 +SOF 2 +SO 2 ) linearly increases with Q sec roughly, which can be the characteristics of DC PD quantity.