环氧基碳纳米管纳米电介质的直流真空沿面闪络特性

Surface Flashover Characteristic of EP/MWCNTS in Vacuum Under DC Voltage

气-固界面的沿面闪络电压低于同等条件下同种气体的击穿电压,从而制约着特高压电力设备的发展。对固体绝缘材料进行改性可以提高气-固绝缘系统的沿面闪络性能。为此,制备了8种不同的多壁碳纳米管(MWCNTS)掺杂环氧树脂,即掺杂质量分数分别为0%、0.02%、0.05%、0.1%、0.125%、0.15%、0.2%和0.5%的8种试样,并对试样进行了显微形貌、玻璃化转变温度、介电常数、表面粗糙度、电阻率、表面电位衰减特性(SPD)、直流真空沿面闪络特性的测试。试验结果表明:随着掺杂质量分数的提高,环氧复合材料的沿面闪络电压先上升后下降,并且在掺杂质量分数为0.1%时达到极大值,环氧复合材料的闪络电压比纯环氧树脂的提升了23.1%。通过分析发现,掺杂质量分数较低时,沿面闪络电压的上升与陷阱深度的增加及介电常数的下降有关;而掺杂质量分数较高时,沿面闪络的下降与浅陷阱密度的增加及介电常数上升有关。通过分析得到,介电常数会引起电场畸变,陷阱的深度和密度会影响载流子迁移过程,二者均对沿面闪络电压产生影响。

The surface flashover voltage of the interface between solid and atmosphere is much lower than the breakdown voltage in the same atmosphere, which restricts the rapid development of ultra-high voltage electrical equipment. The modification of a solid insulating material can improve the flashover performance of the gas-solid insulation system. Consequently, we prepared the epoxy resins with multi-walled carbon nanotobes（MWCNTS） particles in 8 different mass fractions, which are 0%, 0.02%, 0.05%, 0.1%, 0.125%, 0.1%, 0.2%, 0.5%, respectively. Then, the experiments of microscopy morphology, glass transition temperature, dielectric constant, surface roughness, resistivity, surface potential decay（SPD）, and DC flashover in vacuum were conducted. The experimental results show that the surface flashover voltage first increases and then decreases as filler loadings increases, and reaches the climax with the filler doping mass fraction of 0.1%, and the flashover voltage increases 23.1% compared with neat epoxy resin. It is found that the increase of the surface flashover voltage is related to the increase of the trap depth and the decrease of the dielectric constant when the filler doping mass fraction is low, while the decrease of flashover voltage results from the increasing of dielectric constant and the density of shallow traps at high filler doping mass fraction. It can be concluded that the dielectric constant will cause the electric field distortion, and the depth and density of the trap will affect the carrier transport process, both of which will affect the flashover voltage.