直流电晕下环氧绝缘材料的表面电荷特性

Research on Surface Charge Characteristics of Epoxy Insulating Material by DC Corona

环氧树脂广泛应用于电力系统中,其表面电荷的积累和衰减行为已成为制约众多高压直流电力设备研制的关键问题。薄片状介质试样的表面电荷密度与表面电位近似呈线性关系,因此,常通过表面电位衰减行为研究表面电荷的衰减特性。基于栅控负直流电晕充电方法,采用纯环氧试样及几种环氧纳米复合试样,研究环氧树脂的表面电位衰减特性。结果表明:随着栅极电压的增大,环氧树脂表面电位的衰减速度逐渐加快,并在约?8 k V处开始出现"交叉"现象;随电晕时间的增长,环氧树脂表面电位的衰减速度逐渐加快,并在约480 s处达到稳定;环氧树脂的表面电位衰减速度与ε/γ成线性关系,即与介电常数ε成反比、与体电导率γ成正比。

As an insulating material, epoxy resin is widely used in the power system. However, its surface charge accumulation and decay behaviors have been the key problems restricting the development of high voltage direct current power equipment. For flat samples, the density of surface charges can be regarded as having a linear relationship with the surface potential. For this reason, the decaybehavior of surface charge can be directly related to that of surface potential. Based on DC corona charging process, pure epoxy and three kinds of epoxy nanocomposites are used to study the surface potential decay characteristics of epoxy resin in this paper. The experimental results show that the larger the grid voltage is, the faster surface potential decays, and a cross-over phenomenon will appear when the grid voltage exceeds？8 kV; the longer charging time is, the faster surface potential decays, and the decay rate will reach steady state when the charging time attains the threshold time 480 s; surface potential decay rate has a linear relationship withε/γ, i.e., the decay rate is proportional to bulk conductivity γ and inversely proportional to permittivityε.