一起500 kV沿海线路复合绝缘子异常发热原因分析

Abnormal Heating of Composite Insulators in a 500 kV Coastal Transmission Line

沿海线路复合绝缘子长期受高盐雾、海风侵蚀,为了有效判定沿海线路复合绝缘子运行状态,对沿海某500 kV线路开展了无人机复合绝缘子红外测温,发现部分复合绝缘子多部位出现异常发热,1月后复测发现非高压端发热消失,仅剩高压端仍有温升。针对此现象抽取了8支异常发热复合绝缘子试品进行试验分析,包括外观检查、红外测试、芯棒剖检、水扩散试验等。试验结果表明绝缘子发热均位于护套表层,非高压端发热现象由复合绝缘子表面积污引起,高压端发热主要由端部高场强、积污共同作用引发,绝缘子芯棒内部无酥朽缺陷,绝缘子机械性能良好,短期内仍满足运行要求。针对此次复合绝缘子发热提出如下建议:该线路虽仅运行7年,但外观检查发现复合绝缘子伞套材料粉化严重,同时存在部分绝缘子局部芯棒-护套粘结不良缺陷,建议于下次综合检修时全部予以更换;沿海线路长期处于高盐雾、高湿度环境下,需定期对复合绝缘子开展带电检测,并依据检测情况适当缩短复合绝缘子运行年限。

Composite insulators of coastal overhead transmission lines operate under the long-term influ-ence of high salt spray and sea breeze.In order to efficiently detect the operating status of composite insu-lators,UAV infrared inspection was made on a 500 kV line along the coast.Abnormal heating was found at many parts of some composite insulators.One month later,the retest found that the heating at the non high voltage end disappeared,and only the high voltage end still had temperature rise.In response to this phenomenon,8 composite insulators were selected for testing,including visual inspection,infrared test,core dissection and water diffusion test,etc.The results showed that the heating of the composite insula-tors are located on the surface.Heating at the non-high voltage side is caused by surface contamination,and the high voltage side heating is mainly by the high field strength and the pollution.There is no fragile defects inside the composite insulators core,and the mechanical properties are good,which still meet the operation requirements in the short term.The suggestions are:although the insulators has only been in operation for 7 years,the appearance inspection found that outer umbrella material of the composite insu-lators was severely chalked;at the same time,there is poor bonding of some insulators core sheaths;it is recommended to replace all insulators in the next maintenance work.The coastal transmission line has been exposed to high salt fog and high humidity environment for a long time,regular UAV infrared in-spection on composite insulators is necessary,and appropriately shorten the operating life according to the detection result.