Study On Arc Quenching And Interruption Performance Of Eco-Friendly C₄F₇N Binary Gas Mixture

As an insulating gas,SF₆ has excellent insulation and arc extinguishing performance,and is widely used in electrical insulation equipment.However,SF₆ is a greenhouse gas with a high potential for the greenhouse effect,and SF₆ leakage is inevitable in the manufacturing of related electrical equipment and the operation of power grids,exacerbating the greenhouse effect.Therefore,the development of environmentally friendly gas insulating media to gradually reduce the use of SF₆ has become a research hotspot.C₄F₇N is widely concerned due to its excellent insulation and environmental protection characteristics.At present research on C₄F₇N and its gas mixtures mainly focuses on insulation performance,while research on arc extinction and interruption characteristics is very limited.Therefore,based on the arc quenching and interruption characteristics of environmental protection insulating gas C₄F₇N and its mixed gas,the arc characteristics under the fixed nozzle,the breaking performance of environmental protection C₄F₇N hybrid gas and the dielectric recovery characteristics of environmental protection gas insulation circuit breaker are studied.The main research work is as follows.First,based on the local thermodynamic equilibrium theory and the hydrodynamic theory,this study combines the Maxwell equation to establish a mathematical model of two-dimensional magnetohydrodynamics in which the k-εturbulence model is used to simulate the influence of turbulence on the arc characteristics in the flow equation,and the net radiation coefficient is used in the energy equation.The interpolation function is used to complete the input and call of physical parameters,and establish a complete nozzle arc model and circuit breaker to establish the foundation for subsequent research.Secondly,based on the nozzle arc model under a single nozzle and fixed electrode,with SF₆,CO₂,C₄F₇N/CO₂ and C₄F₇N/N₂ gas as the research objects,the arc temperature distribution and electromagnetic field distribution under DC steady state are calculated,and the differences of arc characteristics during arc stable combustion of different gas media are analyzed.After stable arc combustion,by simulating the interelectrode current under zero at the constant rate of change,the small current arc of C₄F₇N binary hybrid gas under air blowing is studied,and the influencing factors of arc extinguishing performance are analyzed combined with the gas physical property parameters.The results show that the arc quenching performance of C₄F₇N binary hybrid gas is between SF₆ and CO₂,and the energy accumulation in the arc radiation absorption zone causes the arc extinguishing performance difference between C₄F₇N binary hybrid gas and SF₆ gas.Considering the performance of all items comprehensively,the C₄F₇N/CO₂ mixed gas has more alternative potential.Finally,based on the multi-physical field coupling model of 40.5kV self-blasting circuit breaker,with the most potential C₄F₇N/CO₂ mixed gas as the study object,the dynamic process of the circuit breaker under different gas media is simulated,and the gas arc breakdown characteristics are analysed combined with the Mayr arc model.According to the flow injection theory,combined with the pederson breakdown criterion,the dielectric recovery mathematical model is established,and the dielectric recovery characteristics of C₄F₇N/CO₂ mixed gas circuit breaker under different filling pressure are simulated.After the comprehensive calculation results,the influencing factors of C₄F₇N/CO₂ mixed gas breaker and C₄F₇N/CO₂ mixed gas alternative are presented.The results show that the difference of heat transfer performance between the C₄F₇N/CO₂ mixed gas and SF₆ is the main reason of the breaking performance gap,and the breaking performance and dielectric recovery characteristics of the C₄F₇N/CO₂ mixed gas can be improved by adding O₂ or increasing the inflation pressure.