一起低压侧区外相间短路引起的主变差动保护误动

Analysis and Treatment of a Differential Protection Mis-operation of the Main Transformer due to External Interphase Short Circuit in the Low Voltage Side

针对柬埔寨达岱水电站主变压器低压侧区外一起差动保护误动故障,通过对变压器保护装置上的主变参数、CT变比,尤其是变压器的绕组组别进行分析,结果表明,主变低压侧区外差动保护误动作是因主变绕组组别整定错误造成的,经处理后,主变恢复正常运行。

In the Tatay Hydropower Station of Cambodia , an external differential protection mis-operation is observed in the low voltage side of the main transformer .With a detailed analysis on the main transformer parameters of the protec-tion device, the current transformer （CT） ratio, and especially the winding groups of the transformer , it shows that this fault could be caused by the wrong setting of the winding groups .Treatment measures are then carried out corresponding-ly.After the treatment , the main transformer operates well .