一起两点接地故障引起主变保护动作的分析

结合保护装置动作情况,对一起主变保护动作事故进行分析。中性点不接地系统异相两点接地的故障波形很有特点,通过一次设备动作情况,对故障波形进行深入分析,对保护动作逻辑进行充分论证。35k V某线路C相发生单相接地,主变35k V引下线A相绝缘套管绝缘下降形成击穿接地,这两个故障点一个在差动保护范围内,另一点在差动保护范围外,这两点为故障电流提供通道,导致故障的发生。深入的分析和对波形产生原因的探讨,为以后同类型故障分析提供参考。

Analysis of Action of Transformer Protection Caused by Two Points Grounding Fault

Combined with the action of the protection device, the fault of the action of the transformer protection is analyzed. The fault waveform is particular when two points grounding fault occurred in differ-ent phases of neutral non-grounding system, so the fault waveform is further analyzed and the protection action logic is demonstrated fully through the action of the primary equipment. The grounding fault occurs in the phase C of the 35kV line, and the insulation of the main transformer 35kV down lead phase A insulating bush declines to form breakdown grounding. The two fault points, one is in the differential protection scope, another is out of the differential protection scope, and then the two fault points supply the channel for fault current and cause the fault. The in-depth analysis and discussion about the reason of waveform provide the reference for such fault analysis.