500kV变压器高压套管末屏接地故障分析及处理

对500 kV船山2号主变压器停电试验发现的U相、V相末屏漏油及放电问题进行分析,检查高压套管末屏,发现U相引线柱根部有油渗出,引出线接地铜套有轻微卡涩,V相周边均有渗漏油,分析认为:U相、V相高压套管末屏故障分别是由于试验操作不当造成的接地不良和引线松动造成的接触不良。进一步对套管油进行油色谱试验,未发现炔烃类气体,认为套管内部无放电发生,放电仅局限于末屏引出线末端。由此得出结论:U相、V相高压套管末屏接地不良,造成末屏对地悬浮电位放电,但放电仅局限于末屏引出线末端,套管内部无故障。通过末屏更换并将接地方式由弹簧金属套接地式变为直接硬连接,消除了故障。

Analysis on Grounding Fault of High Voltage Bushing End Screen of 500 kV Transformer

This paper analyzes problems of oil leakage and electric discharge of U and V phase of 500 kV Chuanshan No.2 main transformer in process of power cut.By checking,it discovers there is oil oozing at the root of U phase lead,the grounding cooper bushing of the lead is slightly blocked and there is oil leaking around V phase.Analysis indicates faults of end screens of U and V phase high voltage bushing are respectively resulted from bad grounding caused by improper testing operation and bad touch caused by loose lead.By further oil chromatogram testing,no alkyne gas is found which leads to the conclusion that there is no electric discharge happening inside the bushing and electric discharge is limited to the end of the lead.It finally draws a conclusion that bad grounding of the end screen of U and V phase high voltage bushing is the main reason for causing discharge to suspended potential over the grounding while electric discharge is only limited to the end of lead and there is no fault inside the bushing.Bu changing the end screen and grounding way from spring metal sleeve ground-ing to direct hard-sired way,it is able to remove faults.