变压器螺柱弹簧压紧结构套管末屏故障原因分析及处理

Cause Analysis and Treatment of an End Shield Foult of Transformer Stud Spring Compression Structure Bushing

某220 kV变电站预试定检过程中发现主变高压C相套管末屏防雨盖打开时有绝缘油渗漏,伴随微量气体喷出,渗漏油中存在疑似游离碳的黑色物体,末屏头部有发黑现象。为进一步对该主变套管末屏缺陷进行分析,通过电气试验、油气试验进行对比,并结合红外测温情况以及末屏接地检查情况,认为该套管末屏接地弹簧长期运行后弹力不足导致末屏接地不良,进而引起末屏放电。为防止类似缺陷发生,提出了相应的处理措施,为后续该类型主变套管缺陷判断提供案例支撑及原因分析。

During the pre-test and inspection process of a 220 kV substation,it was found that there was insulation oil leakage when the rainproof cover of the C-phase bushing end shield of the main transformer was opened,accompanied by a trace of gas spraying.There was a black object suspected of free carbon in the leaked oil,and the head of the end shield turned black.To further analyze the defects of the end shield of the main transformer bushing,a comparison was made through electrical tests and oil&gas tests,combined with the infrared temperature measurement and the grounding inspection of the end shield.It is believed that the insufficient elasticity of the grounding spring at the end shield of the bushing after long-term operation leads to the poor grounding of the shield screen,which in turn causes discharge at the end shield.To prevent similar defects from occurring,corresponding treatment measures are proposed,which provides case support and cause analysis for the subsequent judgment of defects in this type of main transformer bushing.