电压互感器二次单相接地短路故障分析

Analysis on secondary single-phase grounding short circuit fault of voltage transformer

针对电压互感器二次单相接地短路导致非故障相电压升高的情况,通过对电压二次电缆阻抗的测试,电压互感器接地点的改变等试验。分析、阐述了其产生的原因是二次电缆N相线芯阻抗在短路电流流过时产生电压叠加在非故障相线芯上所致。可采取增大N相线芯截面积或退出过电压保护等措施预防其对电网的不利影响。

When single-phase of potemial transformer secondary winding grounds, it raises the voltage of the other two non-fault phases. By measuring the impedance of secondary voltage cable and changing the grounding points, this paper analyzes and expatiates the reason is that the N-phase current of secondary electric cable generates voltage to the other two non-fault phases when grounding current affluxes it. The ways of preventing its effection to electric network are extending the section of N-phase electric cable or blocking the overvoltage protection.