温度对SF_(6)/CF_(4)气体间隙工频放电特性的影响

Effect of Temperature on Power Frequency Breakdown Characteristics of SF_(6)/CF_(4) Mixed Gas

SF_(6)/CF_(4)混合气体具有低液化温度和高绝缘强度,主要应用于低温环境GIS等设备中,有必要研究低温环境下温度对SF_(6)/CF_(4)混合气体的工频放电的影响。为此开展了SF_(6)/CF_(4)混合气体在−50~20℃温度范围内的工频放电试验,得到了稍不均匀电场中击穿电压随温度的变化,以及极不均匀电场中局放起始电压和击穿电压随温度的变化。在稍不均匀电场中,0.7 MPa 20%SF_(6)/80%CF_(4)混合气体的击穿电压随温度降低出现先下降再上升的变化趋势,而0.7 MPa 50%SF_(6)/50%CF_(4)混合气体的击穿电压随温度降低基本保持不变。在极不均匀电场中,0.7 MPa 20%SF_(6)/80%CF_(4)混合气体的尖端缺陷局放起始电压随温度降低而轻微降低,放电量和放电次数随温度降低呈增大趋势,但击穿电压随温度降低基本保持不变。研究结果对于指导SF_(6)/CF_(4)混合气体在低温下的绝缘设计具有参考意义。

Due to its low liquefaction temperature and high insulation strength,SF_(6)/CF_(4) gas mixture is mainly used in GIS equipment in low temperature.The influence of temperature on the power frequency discharge of SF_(6)/CF_(4) mixture gas in low temperature environment is of great significance for understanding the insulation performance of GIS equipment and ensuring safe operation.However,few related researches are available in the literature.In this paper,the AC discharge tests of SF_(6)/CF_(4) mixture in the temperature range of−50~20℃were performed.The variation of breakdown voltage with temperature in slightly inhomogeneous electric field and the variation of initial voltage and breakdown voltage of partial discharge with temperature in extremely inhomogeneous electric field were obtained.In slightly inhomogeneous electric field,the breakdown voltage decreases first and then increases with the decrease of temperature for 0.7 MPa 20%SF_(6)/80%CF_(4) gas mixture;however,it keeps basically unchanged for 0.7 MPa 50%SF_(6)/50%CF_(4) gas mixture.In an extremely inhomogeneous electric field,the initial partial discharge voltage decreases slightly with the decrease of temperature,the discharge quantity and times increase with the decrease of temperature,but the breakdown voltage remains basically unchanged with the decrease of temperature.The research results are helpful for supporting the insulation design of SF_(6)/CF_(4) gas mixture in low temperature environments.