Study On The Arc Quenching Capability Of C₄F₇N/CO₂ Mixed Gas

With the development of electric power technology and the enlargement of power grid scale,SF₆ electrical equipment has been widely used.However,SF₆ gas has a serious greenhouse effect,the power industry needs to significantly reduce or even ban SF₆ gas,scholars around the world have been committed to seeking a replacement for SF₆environmentally friendly gas.In recent years,perfluoroisobutyronitrile?C₄F₇N?gas has been favored by many researchers because of its excellent electrical performance and low global warming coefficient,and is considered as the most potential to replace SF₆ in the field of high pressure.However,due to its high liquefaction temperature limits its scope of use,it needs to be used in conjunction with certain buffer gases?CO₂ gas is currently widely used?.It is important to study the extinction performance of C₄F₇N mixed gas,but there is little research work in this field at home and abroad.Therefore,this paper studies the extinction performance of C₄F₇N/CO₂ mixed gas.In this paper,the research status of gas substitution is introduced,and it is pointed out that C₄F₇N/CO₂ mixed gas has the most potential to replace SF₆.Then arc theory is introduced to lay a theoretical foundation for the follow-up test analysis.Through the design of the test circuit,and then set up an arc test platform,and the test circuit debugging,so that it meets the test needs of precision.Short circuit current cutoff tests were carried out for SF₆,CO₂,1%C₄F₇N/99%CO₂,5%C₄F₇N/95%CO₂ and 9%C₄F₇N/91%CO₂ mixture under0.4Mpa?0.8MPa with 1.6kV circuit voltageat.The arc quenching capability of C₄F₇N/CO₂mixed gas was studied by analyzing arc voltage,arc conductance,arc energy,different open phase angle and energy dissipation coefficient calculated by Mayer equation.The results show that with the increase of C₄F₇N content,The arc quenching capability of C₄F₇N increases gradually.The peak value of arc voltage in 5%C₄F₇N/95%CO₂ mixed gas of 0.6MPa is about 0.67 times of SF₆ and 9%C₄F₇N/91%CO₂ mixed gas is about 0.76 times of SF₆ at 15kA interrupting current.Under the same conditions,the arc quenching performance of C₄F₇N is still lower than that of SF₆ gas,and the dissipation coefficient of C₄F₇N/CO₂ mixture is lower than that of SF₆ gas.By increasing the gas pressure of C₄F₇N/CO₂ mixture,the substitution of SF₆ gas can be realized in a certain situation.The arc conductivity of 9%C₄F₇N/91%CO₂ mixture of 0.8MPa is lower than that of 0.6MPa SF₆ at20kA interrupting current.Decreasing the open phase angle is beneficial to extinguish the arc.After several interruptions in the C₄F₇N/CO₂ mixture,there will be a large amount of black dust,which will affect the arc quenching performance of the gas,and should be cleaned in time.