SF_6及空气中绝缘子表面电荷的消散过程分析

Analysis of Surface Charge Decay Process on Insulators in SF_6 and Air

为了研究绝缘子表面电荷消散的规律,建立了一套表面电荷测量装置,可以测量不同气体中、不同气压下盆式绝缘子的表面电荷分布。采用的测量方法为电容探头法。针对盆式绝缘子的两种典型应用环境,即0.1MPa的空气环境及GIS/GIL中0.5MPa的SF6气体环境,实验测量了0.1MPa的空气中和0.5MPa的SF6中绝缘子表面电荷的消散过程。实验测得绝缘子表面电荷的消散过程近似呈指数衰减过程,时间常数是104 s数量级。结合实验结果,对绝缘子表面电荷消散的3种途径进行了分析,认为表面电荷主要通过绝缘子内部消散,且消散速率与绝缘子的体积电阻率和表面电阻率有关。

The surface of insulators is prone to generate charges under a DC high-voltage for a long time,which has a great impact on insulation performance of the insulators.Surface charges decay by three mechanisms,by volume and surface resistivity of the insulator as well as by neutralization from the gas.To study surface charge decay process on insulators,a set of surface charge measurement device was designed,which could measure the surface charge distribution on insulators in different gases and different air pressures.The insulator which was used during experiments was made of epoxy resin,and the capacitance probe method was used for measurement.The surface charge decay processes were experimentally measured in air at 0.1 MPa and in SF6 at 0.5 MPa.The experimental results reveal that,the decay process of the surface charge is similar to exponential decay process,and the time constant of the decay rate is 104 s.The rates and mechanisms of charge decay in different environments are discussed in particular.The surface charges mainly decay by volume and surface resistivity of the insulator.