不接地系统单相接地故障分析和处理

Analysis and treatment of single-phase grounding fault of the ungrounded system

介绍了6(10)k V中性点不接地系统的组成,分析了系统对地容抗属性,详细阐述了单相接地短路电流与非接地相对地电压矢量理论关系,以及电压互感器开口三角作用。重点论述了工程实际应用中存在的电压互感器铁磁谐振过电压、电压互感器二次错误接线及切换并列装置存在的问题等,针对需要注意的事项,明确了单相接地事故的危害和防范措施。

The constitution of the 6（10）k V neutral point ungrounded system is introduced. The properties of the system capacitance to the earth are analyzed. The relationships of the vector theory between the single-phase grounding fault current and the ungrounded-phase voltage to the earth as well as the effect of the voltage transformer opening triangle are presented. The existing ferromagnetic resonance overvoltage of voltage transformer in the practical engineering application,the voltage transformer secondary wiring errors and some problems exist in switching parallel device are discussed. Aiming at the matters that should be paid much more attention,the harms and the relevant preventive measures of the single-phase grounding accidents are also given.