220kV某站#2主变变低5020隔离柜内CT异常开路的缺陷分析

Defect Analysis of CT Abnormal Opening in Low 5020Isolation Cabinet of 220 kV Main Transformer

本文阐述了220 kV某站主变变低5020隔离柜在拆除过程中在没有进行二次措施保护的情况下向上抽提了穿心CT,同时该站10 kV开关柜CT采用了多芯电缆配线耳压接的方式,且压接过程中未采用专用压线钳进行压接,压接不牢固,导致CT在被提拉过程中二次电缆接线端子也受力拉拽,致使二次接线端子出现松脱的情况。在运行中,正常运行时负荷较小,电流也相对较小,由于电容器突然的投入,电流急剧升高,松脱铜线和线耳在大电流的作用下在两者间产生了一个过电压,过电压导致CT绝缘部分持续放电,CT绝缘持续损坏并出现烧熔的情况。该事件最终由于值班人员及时发现,最终避免了更大事故的发生。

This paper expounds that in the process of demolition of main transformer low 5020 isolation cabinet in a 220 kV station,the core-piercing CT is extracted upward without secondary protection.At the same time,the multi-core cable distribution ear is used in the 10 kV switch cabinet CT of the station,and the special clamp is not used in the process of pressing connection,and the pressing connection is not firm.The secondary cable terminal of CT is also pulled by force in the process of being pulled,which results in the loosening of the secondary cable terminal.In normal operation,the load is small and the current is relatively small.Due to the sudden input of capacitors,the current rises sharply.Loose copper wires and wire ears produce an overvoltage between them under the action of large current.The overvoltage causes the continuous discharge of CT insulation,and the continuous damage of CT insulation and the occurrence of melting.Eventually,the incident was discovered urgently by the duty officers,which eventually avoided the occurrence of larger accidents.