Numerical Calculation and Analysis of Fluid Characteristics of Gas Chamber Environmental Protection Type 1100kV GIL HSGS during Breaking Process

The environmentally friendly C4F7N gas and its feasibility of application in switchgear are one of the hot spots in the field of electrical engineering. In this paper, a two-dimensional dynamic calculation model for 1100kV GIL high speed grounding switch(HSGS) was established based on the theory of fluid dynamics for the opening process of 1100kV GIL HSGS. By changing the type of C4F7N mixed gas in the gas chamber, the proportion of C4F7N and the basic pressure in the gas chamber, the finite element method was used to carry out arc simulation calculation on the model and the pressure, temperature and density changes of the mixed gas in the gas chamber of the HSGS were obtained. The study analyzed the effects of C4F7N mixed gas type, C4F7N ratio and base pressure of gas chamber on the arcing characteristics of HSGS. The calculation results show that increasing the pressure and the proportion of C4F7N can enhance the arc blowing effect, effectively reduce the arc channel temperature, and increase the arc channel density during arcing; Comparing the three C4F7N mixed gases, C4F7N/CO2 has the lowest arcing temperature, and the strongest arc blowing effect and the highest arc density when C4F7N accounts for 5% and 9%. When the proportion of C4F7N is 13% and 20%, C4F7N/N2 arc temperature is higher. Moreover, it has the strongest arc blowing effect and higher arc path density. C4F7N/Air has the highest arcing temperature, its blowing effect and arc channel density are lower than the other two mixed gases. The results can lay a theoretical foundation for the research of C4F7N mixed gas in arc extinction.