三极直线法测量接地阻抗的误差分析研究

通过推导均匀土壤中半球状接地极的接地阻抗采用三极直线法测试的误差公式和实际测试,指出按DL/T 475-2006《接地装置特性参数测量导则》(简称:《导则》)中的直线法的测试结果来判断接地阻抗误差较大,不够准确,应予以适当地修正。工程实际测量数据表明:接地阻抗的测量误差由于受制于电压极距与电流极距的倍数、电流极距与接地装置等效直径的倍数影响,很难达到《导则》要求,应将导则中"三次测试结果误差在5%以内"修正为"三次测试结果误差在11%以内",对现场实际测量才具有指导意义。

Error Analysis of Ground Impendence Measurement based on Three-Electrode Straight Line Method

According to the error formula deduction of ground impendence of hemisphere ground electrode in uniform soil based on three-electrode straight line method and the results of actual measurement,it is pointed out that the error of ground impendence measurement based on the straight line method in DL/ T 475-2006 (Guide in short) is great and the Guide should be revised properly.Actual measurement data show that the error of ground impendence measurement is influenced by the multiple relationship between voltage polar distance and current polar distance,and the multiple relationship between current polar distance and equivalent diameter of ground device,and thus is difficult to achieve the demand of the Guide.The Guide will have guiding significance to actual measurement after its sentences of "measurement errors in three times are within 5%" is revised to "measurement errors in three times are within 11%".