固体绝缘沿面缺陷下的SF₆分解特性及机理

In order to lay a foundation for application of gas analysis method in diagnosing surface defect on the solid insulation,we constructed an experimental platform to study the decomposition characteristic of SF₆ under surface defect. Besides, the calculation method of quantum chemistry was adopted to explore the formation path of several kinds of key products. Experimental results show that main characteristic products under surface defect on the solid insulator include two kinds of sulfur-containing products and four kinds of carbon-containing products: SOF₂, SO₂, CO, CO₂, CF₄, and CS₂. Contents of CO₂, CO, and CS₂ grow rapidly from 0.46×10^-6, 4.22×10^-6, and 18.69×10^-6 to 2.05×10^-6, 14.76×10^-6, and 27.77×10^-6, respectively. Therefore, it can be assumed that their formation rates are important characteristic parameters for determining defect severity. Complex chemical reactions happen when surface discharges occur on the solid insulator. CF₄ is mainly derived from the reactions between carbureted hydrogen, F, and HF. CO is derived from oxidative dehydrogenation of carbureted hydrogen. CO₂ is generated through various ways including oxidation of fluorocarbon, oxidative decomposition of CO, and oxidative dehydrogenation of carbureted hydrogen. CS₂ is generated be the reaction between CH_x and S₂ or CH_x and H₂S. The fault cases prove the practical value of the research results in actual production.