地铁地网反向法测试接地阻抗研究

接地阻抗是地铁地网测试的重要内容之一。在实际工作中很少使用反向法测试接地阻抗。对石家庄地铁1号线南村站地网进行了反向法实地测试试验,分析了试验数据,并与直线补偿法的试验结果进行了比较。试验结果表明,在土壤电阻率相对均匀的情况下,反向法能有效降低电流线和电位线线间互感因素的影响,但是测试得到的总体的接地阻抗数值偏小。其结果可以作为接地网测量结果的下限值,如果其他方法测试的结果小于反向法测量结果,则可认定其他的测量存在一定的错误;如果反向布置的电位极和电流极间的距离相当大,则可以用此法得到被测接地装置的真实接地阻抗;如果允许接地阻抗测试结果的误差在一定范围内,通过合理布设电流线和电位线的长度,可以把反向法作为地铁地网接地阻抗的测试方法。

Researches About Ground Impedance Measurement of Subway Grounding System Using Reverse-direction Method

Grounding impedance is one of the important contents of subway earthing network test. Reverse-direction method on testing grounding impedance is used rarely in actual practice. Testing experiment using reverse-direction method was carried out in the Nancun station of Shijiazhuang Metro line 1, the test data was analyzed and compared with the test data using linear compensation method. The results showed that: using reverse-direction method can effectively reduce the influence of mutual inductance between the current line and the potential line in the condition that soil resistivity was relatively homogeneous, but the data of general grounding impedance by tested was relatively small. The results using reverse-direction method could be used to be the lower limit of the grounding grid measurement results, and if the measurement results using other methods were less than that results, it could be considered existing certain errors. If the distance between reverse arranged potential electrode and current electrode was quite large, the real grounding impedance of grounding device being measured could be obtained using this method. If the error of the grounding impedance test results being controlled in proper range was allowed, reverse-direction method could be used as the test method of grounding impedance for subway earthing network by reasonable distribution of the length of current line and potential line.