Study On Partial Discharge Characteristics And Impulse Voltage Breakdown Characteristics Of HFO1234ze（E）/N₂ Mixture

Trans-1,1,1,3-tetrafluoropropylene（HFO1234ze（E））is a new SF₆alternative gas with high electrical resistance and environmental protection.The pure HFO1234ze（E）has a higher liquefaction temperature under high pressure,which can reduce the liquefaction temperature by adding buffer gas N₂,and at the same time save cost and improve economic performance.In order to explore the optimal mixing ratio of HFO1234ze（E）/N₂mixture and its tolerance to different voltage waveforms,this paper studied the partial discharge characteristics of HFO1234ze（E）/N₂under the action of power-frequency voltage and the breakdown characteristics under the action of lightning impulse voltage respectively by using the gas insulation test platform.The partial discharge test tested the partial discharge initial voltage of insulating gas under positive and negative half cycles,and took SF₆/N₂under the same condition as the control group to explore the influence of air gap distance,mixing ratio and gas pressure on the insulation performance of HFO1234ze（E）and its mixed gas.The experimental results show that the initial discharge voltage of the negative half-cycle partial discharge under the condition of pure HFO1234ze（E）under different pressures can reach 0.96 to 1.04 times that of pure SF₆.The partial discharge initial discharge voltage of 40%HFO1234ze（E）/60%N₂mixture gas at 0.3MPa is0.67 to 0.89 times that of SF₆/N₂under the same condition,which has a great application prospect in medium and low voltage electrical equipment.The impulse voltage breakdown test investigated the 50%impulse breakdown voltage of HFO1234ze（E）/N₂and SF₆/N₂mixed gases under the action of positive and negative polarity impulse voltages under the same conditions with electric field uniformity,air gap distance,mixing ratio and gas pressure as variables.The test results show that the breakdown voltage increases with the increase of mixing ratio and electrode spacing under the action of positive and negative polarity impulse voltages.The breakdown voltage under the action of negative polarity impulse voltage can reach 0.65-0.82 times that of SF₆/N₂under the same condition in the slightly uneven electric field of ball-plate 20mm apart.The breakdown voltage at0.3MPa is most similar to SF₆/N₂.Under the action of positive polarity impulse voltage,the breakdown voltage of this proportion of mixed gas is slightly higher than that of negative polarity.Under the action of positive polarity impulse voltage,the breakdown voltage of SF₆/N₂can reach 0.66-0.85 times that of SF₆/N₂under the same condition.Its insulation performance is most similar to that of SF₆/N₂at0.15MPa.The breakdown voltage of and 40%HFO1234ze（E）/60%N₂in the range of0.2-0.3MPa under extremely heterogeneous electric field is slightly higher than that of SF₆/N₂mixture gas.Based on partial discharge and impulse voltage breakdown characteristics test,this paper comprehensively considers the insulation performance,liquefication temperature,environmental impact degree,economic performance and other factors of HFO1234ze（E）/N₂mixture,and proposes that 40%HFO1234ze（E）/60%N₂mixture has the potential to replace SF₆gas in low and medium voltage electrical equipment as a new generation of environment-friendly insulating gas.