500 kV变压器无励磁分接开关放电故障诊断分析

Fault Diagnosis and Analysis of 500 kV Transformer Non-Excitation Tap-Changer Discharge

无励磁分接开关出现放电性故障会严重危害变压器安全运行。介绍了一起500 k V变压器交接试验过程中脉冲局部放电试验异常的案例,应用脉冲电流法、特高频法、超声波法等多维局部放电检测技术进行时差定位,成功诊断了变压器无励磁分接开关内部异物放电故障;通过材质成分分析判断异物为动触头旋转轴压环的机加工碎屑,异物位于无励磁分接开关动触头旋转轴位置,随挡位切换而移动,导致各个挡位均可检测到局部放电,且脉冲局部放电量随挡位变化而变化。

The discharge failure of the non-excitation tap-changer will seriously endanger the safe operation of the transformer.In this paper,a case of abnormal pulse partial discharge test during the handover test of 500 kV transformer is introduced,and the multi-dimensional partial discharge detection technologies such as pulse current method,ultra-high frequency method,and ultrasonic method are used to locate the time difference,and the internal foreign body discharge fault of the transformer,s non-excitation tap-changer is successfully diagnosed.Through the analysis of material composition,it is judged that the foreign body is the machined debris of the rotating shaft pressure ring of the moving contact,and the foreign body is located at the position of the rotating shaft of the moving contact of the non-excitation tap-changer and moves with the gear switching,resulting in partial discharge being detected in each gear,and the amount of pulse partial discharge changes with the change of gear.