一起500 kV CVT二次电压异常分析及预防

Study and Prevention on Abnormal Secondary Voltage of 500 kV CVT

电容式电压互感器(CVT)二次电压异常多因电容元件击穿、绕组短路等因素引起。本文基于一起实际的500 kV电容式电压互感器二次电压偏低异常,根据相关分析,发现此产品的电容元件串联时采用插入铜质引线片的方式,使得引出片与铝箔极板连接处成为薄弱点,均匀的极板结构若发生细微改变,如插接时工艺控制不严或有毛刺,这会导致局部场强集中极易发生击穿。通过本次二次电压异常偏低缺陷,运行单位要加强监测,并建议制造厂家进一步改善引出线结构,加强工艺管控,以预防类似现象的发生,保证电力系统稳定运行。

The abnormal secondary voltage of the capacitor voltage transformer （CVT） is mainly caused by such factors as breakdown of capacitor element and short circuit of winding etc. In this paper,it is found from a real CVT which has lower secondary voltage and through related analysis that insertion of copper lead sheet in the series of the capacitor element of the product causes the connection point of outlet sheet and aluminum foil to become into a weak point. Slight change of even pole sheet structure, such as weak process control in the insertion or burr,can cause partial field strength concentrate and is easy to lead to breakdown. As for the abnormal low secondary voltage, the operation unit shall strengthen monitoring and the manufacturer is also suggested to improve the structure of outlet lead,strengthen process management and control so to prevent the similar fault and assure stable operation of power system.