电位降法测量接地电阻时电流极引线长度的影响

讨论了电流极引线长度对变电站接地电阻测量误差的影响,分析得到了不同土壤结构所要求的电流极引线长度。采用反向法测量接地电阻时,测量得到的接地电阻比真实接地电阻要小,但可将反向法测量得到的接地电阻作为变电站接地电阻测量值的下限。采用全球定位系统(global positioning system,GPS)确定测量电极与接地网之间的距离后,能够根据电位降法比较准确地测量接地电阻。实际测量结果表明,如果电流极引线过短,可通过辅助分析的方法得到实际接地电阻的电压极补偿点位置。

Influence of Length of Current Electrode in Grounding Resistance Measurement by Fall-of-Potential Method

The influence of current electrode's length on measuring error of substation grounding resistance is researched, and the current electrode lengths for different soil textures are obtained. When the method that the current and potential electrodes are in opposite direction is used to measure the grounding resistance, the measured result is smaller than its actual value, however this measured value can be used as the lower limit of measured substation grounding resistance. After the distance between measuring electrode and grounding mesh is determined by global positioning system (GPS), the grounding resistance can be more accurately measured by fall-of-potential method. Actual measured results show that if the lead of current electrode is too short, the position of compensating point of actual grounding resistance's voltage electrode can be obtained by means of auxiliary analysis method.