Experimental Study On Arcing Characteristics Of SF₆/N₂,C₄F₇N/CO₂ Mixed Gas

SF₆has excellent insulation and arc extinguishing properties,and is widely used in power equipment.However,SF₆is a strong greenhouse gas,and its liquefaction temperature is relatively high.Therefore,it is necessary to explore the environment-friendly SF₆alternative gas.SF₆and N₂have a strong positive synergistic effect and show high insulation properties,so the development prospects of their mixed gases are very broad.In recent years,in order to reduce the consumption of SF₆gas,State Grid Corporation has also strengthened the research on 30%SF₆/70%N₂mixed gas and has achieved significant results.In addition,C₄F₇N gas has received extensive attention due to its excellent insulation,arc extinguishing performance and low global warming coefficient.However,its own liquefaction temperature is relatively high,and it needs to be used in conjunction with some buffer gases（CO₂gas is most commonly used at present）.In order to study the arcing performance of SF₆/N₂and C₄F₇N/CO₂mixtures,this paper uses a self-designed arc test platform as a carrier to study the arc characteristics of SF₆/N₂and C₄F₇N/CO₂mixtures.The research is mainly divided into the following aspects:（1）Use the LC oscillating circuit as the test power source,design and process the arc test tank,and assemble the test tank pneumatic operating mechanism.Calculate the relevant parameters of the experimental loop,select voltage,current and stroke measurement equipment,install and debug information reading equipment such as high-speed cameras,oscilloscopes,and complete the construction of the experimental platform.Under 0.3MPa and0.5MPa gas pressure,SF₆,C₄F₇N and N₂,CO₂mixed gas interrupted 0.4k A and 1k A short circuit current arc test respectively,and the arc voltage,current and arc shape information were collected.（2）Process the arc voltage and current data,analyze the changes in arc voltage and current waveform during arcing,and study the volt-ampere characteristics of the arc;Under0.3MPa and 0.5MPa gas pressure,SF₆,50%SF₆/50%N₂,30%SF₆/70%N₂,5%C₄F₇N/95%CO₂,10%C₄F₇N/90%CO₂mixed gas breaks 1k A short-circuit current,the arc voltage,conductance and accumulated energy characteristics are compared and analyzed,and the gas types,The influence of charging pressure on arc characteristics.Analyze the difference in arc characteristics of SF₆,30%SF₆/70%N₂,10%C₄F₇N/90%CO₂mixed gas at 0.5MPa pressure when interrupting 0.4k A and 1k A short-circuit current respectively,and study the effect of short-circuit breaking current on arc ignition characteristics.Quite Mayr equation,calculate the arc time constant of different kinds of mixed gas,and further study the gas thermal breaking characteristics.（3）Combine the arc images obtained by shooting,study the arc shape characteristics and changing laws during the arcing process.Under the same charging pressure and short-circuit breaking current conditions,the difference of different types of mixed gas arc images is studied.The arc image processing technology is used to calculate the transverse diameter of the arc,and the change trend of the arc diameter and the size distribution of the arc diameter of different types of mixed gases during the arcing process are studied.Analyze the arc decomposition products of different kinds of mixed gases,and comprehensively discuss the arc performance of the gas.