液氮中聚四氟乙烯冲击沿面闪络的极性效应  

Polarity effect of impact surface flashover of polytetrafluoroethylene in liquid nitrogen

作　　者：李力 宋萌 史正军 Li Li;Song Meng;Shi Zhengjun(Electric Power Research Institute of Guangdong Power Grid Co.,Ltd,Guangzhou 510080,China;Joint Laboratory on Power Superconducting Technology of China Southern Power Grid Co.,Ltd,Guangzhou 510080,China;China Southern Power Grid Power Technology Co.,Ltd,Guangzhou 510080,China)

机构地区：[1]广东电网有限责任公司电力科学研究院,广州510080 [2]南方电网公司电力超导联合实验室,广州510080 [3]南方电网电力科技股份有限公司,广州510080

出　　处：《低温工程》2023年第6期58-62,共5页Cryogenics

基　　金：南方电网公司科技项目“10Mvar超导同步调相机样机研制”资助(GDKJXM20172779)。

摘　　要：为了探究液氮浸渍下的沿面放电问题,对聚四氟乙烯在液氮环境中极不均匀电场下的沿面闪络电压进行了测量。结果表明其极性效应表现出正极性脉冲下的沿面闪络电压普遍高于负极性时的规律。通过对闪络痕迹的分析,结合电场分布仿真和液氮中沿面闪络机理的理论研究,提出液氮环境中沿面闪络极性效应的表现与变压器油相反的原因是液氮介质极易气化,在闪络过程中气化层的形成较容易,而液氮介质相对于气化层内的氮气产生空间电离的程度要小得多。In order to study the problem of along-plane discharge under liquid nitrogen im-pregnation,the along-surface flashover voltage of polytetrafluoroethylene in extremely inhomoge-neous electric fields in liquid nitrogen was measured.The result showed that the along-surface flashover voltage under positive polarity pulse is generally higher than that in negative polarity.Through the analysis of the flash traces,combined with the simulation of electric field distribution and the theoretical study of the along-surface flash mechanism in liquid nitrogen,the reason why the polarity effect of flashover along the surface in liquid nitrogen environment is opposite to that of transformer oil is that the low temperature of liquid nitrogen medium is extremely easy to vaporize,the formation of vaporization layer is easier in the flash process,and the degree of spatial ionization of liquid nitrogen medium is much smaller than that of nitrogen in the gasification layer.

关 键 词：液氮环境 聚四氟乙烯 冲击沿面闪络 极性效应 

分 类 号：TB663[一般工业技术—制冷工程]