Correlation analysis between formation process of SF6 decomposed components and partial discharge qualities

To obtain relationship between concentration of SF6decomposed characteristic components (or their concentration ratio) during the formation process and partial discharge qualities and pulse repetition rate, this paper used needle-plate electrode to simulate outthrust insulation fault and conducted a serial of experiments. First, the SF6decomposition characteristic under different PD strengths is obtained. Then this paper defines average discharge qualities per second as QSEC. It considers both apparent discharge qualities and discharge pulse repetition rate, and analyzes the relation feature between SF6decomposition characteristic (both concentration of component and their effective formation rates RRMS) and QSEC. Besides, it proposes C(SO2F2)/C(SOF2) as the energy characteristic ratio (ER) to represent PD energy, and defines the effective energy characteristic ratio as (ERRMS). Moreover, it achieves the inner correlation feature between QSECand all the characteristic component concentration, the RRMS of each characteristic component and ERRMS. The results show that: since number of C atoms from stainless steel surface and content of trace H2O and O2in gas chamber were limited, both decomposed component concentration and component concentration ratio accords with the famous "Logistic Population Model" growth trend in ecology, which means they present "S"-curve increase with QSEC. The proposed ER can effectively indicate the amount of PD energy and the defined ERRMScan objectively reveal the variance regularity of PD energy with QSEC. Hence, the correlation mathematic formula between ERRMSand QSECis obtained and ERRMScan be used as the new characteristic parameter to represent PD energy. It establishes the foundation for the further fault diagnosis research.