一起末屏表面潮气对220kV主变套管介质损耗测量的影响案例分析  

Case Analysis on Influence of End Shield Surface Moisture on Dielectric Loss Measurement of 220 kV Main Transformer Bushing

作　　者：周妺末 杨小涛 唐林凯 赵纲 欧昌宇 ZHOU Momo;YANG Xiaotao;TANG Linkai;Zhao Gang;OU Changyu(State Grid Mianyang Power Supply Company,Mianyang 621000,China)

机构地区：[1]国家电网绵阳供电公司,四川绵阳621000

出　　处：《绝缘材料》2020年第9期75-80,共6页Insulating Materials

摘　　要：电容量(C)与介质损耗因数(tanδ)测量是工程中常用于评估高压套管绝缘性能的基本手段。为深入探究工程实际中影响C与tanδ测量误差的主要因素,针对一起220 kV主变110 kV侧套管tanδ测量结果为负值的案例,讨论了出现此种现象的可能原因并对案例进行故障排查。在现场介质损耗试验数据异常的情况下,以末屏暴露在空气中的时长及隔绝潮气的时长为变量,分析C与tanδ随潮气隔绝时间的变化情况并对出现该现象的原因进行讨论。结果表明:使用环氧树脂材料作为末屏引出小套管结构的套管中,末屏对地阻抗受潮气影响较大,致使tanδ测量出现负值,造成套管介质损耗试验不合格的假象。最后,基于案例分析结果对高压套管预试、维护、检修等环节提出了相关建议。Capacitance(C)and dielectric loss factor(tanδ)measurement are the basic methods to evaluate the insulating properties of high-voltage bushing in engineering commonly.In order to further explore the main factors affecting the measurement errors of C and tanδin engineering practice,aiming at a case in which tanδtest result of 110 kV side bushing for 220 kV main transformer was negative,we discussed the possible causes of this phenomenon and conducted troubleshooting.In the case of on-site abnormal dielectric loss test data,taking the exposing time of end screen to the air and isolating time from moisture as variables,the change of C and tanδwith moisture isolation time were analyzed,and the causes of this phenomenon were discussed.The results show that in the busing that using epoxy resin material as the end screen,the impedance of end screen to the ground is greatly affected by the moisture,making the tanδtest value be negative and causing the false appearance that the dielectric loss measurement of busing is unqualified.At last,on the basis of results of case analysis,relevant suggestions are put forward for the pretest,maintenance and overhaul of high-voltage busing.

关 键 词：油浸电容式套管 介质损耗 负值 环氧树脂 潮气隔绝 

分 类 号：TM855[电气工程—高电压与绝缘技术]