绝缘子表面电场及电荷的测量

Measurements of Electric Field and Charge on Insulator Surface

绝缘子表面电荷积聚及其引起的表面电场分布畸变是导致绝缘子表面闪络电压低的主要原因。对绝缘子表面电场及电荷分布进行测量有助于正确地设计绝缘子。为此,在阅读大量相关文献及进行技术调研的基础上,结合作者目前正在进行的研究,对绝缘子表面电场及电荷的测量技术进行了综述。首先简要分析了绝缘子表面电荷的来源(场致发射、局部放电、固体介质夹层极化、电导率分布不均匀或非线性、表面金属微粒等),然后详细介绍了几种绝缘子表面电荷及电场的测量技术,包括静电探头法(有源静电探头和无源静电探头)、粉尘图法、电光法(克尔效应和普克尔斯效应),最后分析了这几种方法的优缺点。

It is well known that the flashover voltage of an insulator between two electrodes is much lower than the breakdown voltage of the same gap in the absence of insulator.The reduced value of the breakdown voltage is generally attributed to the surface charging of the insulator and resulting inter-electrode field modification.In order to correctly design an insulator,it is desirable to measure the distribution of the electric charge and field on the insulator surface.Consequently,the techniques for the measurements of the electric charge and field on an insulator surface are reviewed.Field-emitted electrons,partial discharge,dielectric interface polarization,variations in bulk or surface conductivity,non-linear field-dependent conductivity,and metallic particles are responsible for the charge accumulation on insulator surface.Three techniques for the measurements of the electric charge and field on the insulator surface are described and compared,including capacitive probe,dust figure and electro-optical measurement based on Pockels effect or Kerr effect.