沿绝缘表面空气间隙击穿特性的试验研究  

Experimental Study of the Breakdown Characteristic of the Air Gap Along Dielectric Surface

作　　者：李健[1] 周军[2] 黄瑞平[2] 梅红伟[3] 关志成[3] 王黎明[3] 

机构地区：[1]国网湖北省电力公司电力科学研究院,武汉430000 [2]中国电力科学研究院,北京100000 [3]清华大学深圳研究生院,深圳518000

出　　处：《高压电器》2017年第5期1-6,共6页High Voltage Apparatus

基　　金：国家重点基础研究发展计划项目(973计划)(2011CB209406)~~

摘　　要：目前,针对染污绝缘表面局部电弧发展机理主要有两种观点:一种认为是电击穿过程;另一种认为是热击穿过程。论证两种观点的关键在于判断局部电弧弧根处的场强是否达到弧根前端空气间隙的击穿强度。虽然关于空气间隙的击穿强度的研究工作较多,但是目前还缺少沿绝缘表面空气间隙击穿特性的研究。笔者旨在研究沿绝缘表面空气间隙的击穿特性,分析其与纯空气间隙击穿特性的差别以及海拔因素的影响,同时在试验中考虑绝缘介质表面染污状态包括洁净干燥表面、染污干燥、染污自然受潮以及染污饱和受潮等对其击穿特性的影响。试验首次测量得到了沿绝缘表面空气间隙在不同表面状态、不同气压条件下的击穿强度。测量结果表明:绝缘表面的存在会降低空气间隙的击穿强度,且间隙越短,影响程度越大;沿绝缘表面的空气间隙击穿强度随着海拔升高而降低,但是其随海拔下降程度要小于纯空气间隙的下降程度。通过对比局部电弧弧根附近场强的测量值和绝缘表面空气间隙的击穿强度发现:弧根前端的电场强度能够达到沿绝缘表面空气的击穿强度,说明局部电弧前段发生电击穿是可能的,因此在对污闪过程进行建模分析中需要考虑弧根前端空气间隙的电击穿过程。There are mainly two opinions about the mechanism of propagation of local arc along a polluted dielectric surface： electrical breakdown process or intense thermal ionization process ahead of the arc that causes the arc propagating. The key point is to determine whether the electric field can reach the breakdown strength of the air gap ahead of the arc roots. Although the electric break characteristic of the pure air gap had been investigated comprehensively,there was still lack of research on the characteristic of air gap along a dielectric surface. This paper devotes to investigate the difference of the dielectric strength gap along a dielectric surface as well as the influence of altitude. The effects between pure air gap and air of different dielectric surface conditions on the breakdown voltage are also studied including dry-clean, dry-polluted, nature-moistened and wet polluted. The experimental results show that the existence of dielectric surface would reduce the breakdown strength of air gap, and the shorter the gap distance, the greater of the influence. Also, the breakdown strength of the air gap along a dielectric surface would decrease with the increase of altitude,but the influence of altitude is smaller than that on the breakdown strength of pure air gap. Comparing with the measured results of electric strength ahead of arc roots,it is found that the electrical breakdown process ahead of the partial arcs is reasonable to occur and should be taken into consideration when modeling the polluted flashover process.

关 键 词：沿面间隙 空气间隙 高海拔 弧根 电击穿 

分 类 号：TM501.2[电气工程—电器]