摘要
液氮环境中绝缘材料的沿面闪络特性对超导电力装置的绝缘设计具有重要意义。为此,选择玻璃纤维增强环氧树脂复合材料(G/R)和挤出成型的聚四氟乙烯材料(PTFE),通过实验研究了他们在液氮中的冲击沿面闪络电压和闪络时间的变化特征。结果表明:G/R材料的冲击沿面闪络特性很差,闪络电压值愈高则闪络电压的下降率愈大,而闪络次数愈多则闪络电压值愈低;PTFE材料表现出了良好的沿面闪络电压重复性。其主要原因是高能量的沿面闪络电弧会改变G/R材料表面状况,同时也使环氧树脂基体发生分解,改变了表面电阻率。G/R材料的沿面闪络电压略低于PTFE材料,其原因是相对于PTFE,G/R的介电常数与液氮的偏离更大,电场线更加扭曲,导致其交界面的闪络电压更低。2种材料在液氮环境中服从韦伯分布的0.1%闪络概率的首次冲击闪络电压和爬电距离的关系,可以为在稍不均匀电场条件下工作的超导电力设备的外绝缘设计提供参考。
The surface flashover characteristics of insulation materials are important for the insulation design of HTC electric equipment. Hence, taking glass fiber enhanced epoxy composite material（G/R） and extruded polytetrafluoroethylene（PTFE） as the example, we studied their impulsive surface flashover voltages as well as the lags of flashover time in liquid nitrogen through experiments. According to the experiment results, G/R had poor impulsive surface flashover characteristics： the flashover voltage reduces faster when its value gets higher, but the voltage gets lower when G/R had flashovers more frequently. Meanwhile, PTFE＇s impulsive flashover voltage showed has good repeatability. Further analysis indicates that the phenomenon shows mainly because flashover arcs changed the surface condition of G/R and consequently caused thermal decomposition that varied the material＇s surface resistivity. As for PTFE, it has higher impulsive flashover voltage than G/R since the dielectric constant of G/R is more different from that of liquid nitrogen and this leads to more distorted electric field lines that induces lower surface flashover voltages. We summarized the relation of 0.1% flashover probability initial impulsive voltage obeying the Weibull plot to creeping distance for the two materials from the experiments. The relation could be used as reference for outer insulation design of HTC electrical equipment working in quasi-uniform electric field.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2015年第2期654-661,共8页
High Voltage Engineering
基金
国家自然科学基金(51277063
51407013)~~
关键词
玻璃纤维增强环氧树脂复合材料
聚四氟乙烯
冲击沿面闪络
液氮环境
韦伯分布
闪络痕迹
glass fiber enhanced epoxy composite material
polytetrafluoroethylene
impulse surface flashover
liquid nitrogen circumstance
Weibull plot
flashover trace
