THDF125/67型发电机定子绕组环形引线直流耐压放电分析及处理

Analysis and Treatment of Direct Current Withstand Voltage Discharge for THDF125/67 Generator Stator Winding Circular Lead

针对某THDF125/67型1000MW汽轮发电机定子绕组直流耐压试验放电问题,经过多次直流耐压试验,发现是定子绕组环形引线放电。分析放电原因是环形引线裸露的接地紫铜片没有涂刷环氧胶黏剂导致电场分布不均匀,裸露紫铜片位置的电场强度过高,当电场强度达到空气的击穿场强时,裸露紫铜片发生沿面放电。拆除玻璃纤维带,对裸露紫铜片彻底涂刷环氧胶黏剂后,发电机泄漏电流和直流耐压试验通过。最后对环形引线运行接地线的安装工序提出建议,以防止同类放电故障的发生。

In allusion to the direct current withstand voltage discharge problem of a THDF125/67 type 1000 MW turbogenerator stator winding, it is found that the discharge is caused by the stator winding circular lead after several direct current withstand voltage tests. The reason of the discharge is that the electric field distribution is not uniform due to the non-brushing epoxy adhesive on the ground copper sheet exposed by the circular lead. And the electric field intensity of the exposed copper sheet is too high, when the electric field intensity reaches the breakdown field strength of the air, the exposed copper sheet produces surface discharge. After removing glass fiber strip and thoroughly brushing epoxy adhesive to exposed copper sheet, the leakage current and direct current withstand voltage test of the generator were passed. Finally, some suggestions are put forward for the installation procedure of the circular lead wire to prevent the similar discharge faults.