垂直型直流接地极散流特性试验研究

Experimental Study on Current Distribution of Vertical DC Grounding Electrode

垂直型直流接地极占地面积小,能将电流导入地底深处,有利于改善跨步电压和接触电势,对环境影响小,是一种可行的新型直流接地极布置方式,但垂直型接地极存在散流分布不均匀的问题。用接近实际工程的方法埋设了3根垂直型直流接地极,并注入直流电流,模拟接地极真实运行环境,对其散流特性、电流分配、接地电阻、跨步电势和利用系数进行了测量。试验表明,接地极散流不均匀,下部散流大于上部,且存在明显的端部效应,但由于其将电流导入地底深处,有效地改善了跨步电势;多根并联接地极间的电流分配受接地极之间的屏蔽作用和接地极接地电阻的共同影响;试验测得的利用系数与理论计算值具有较高的吻合程度,验证了理论计算方法的准确性。

Vertical DC grounding electrode has advantages of small occupation area,transporting the current into the deep underground,improving the step-voltage and contact potential,and small impact on the environment. However,vertical DC grounding electrode has a problem of uneven current distribution. In this study,three vertical DC grounding electrodes are placed approaching to the actual engineering,and DC currents are injected into the electrodes to simulate the real working environment. The current distribution,step-voltage distribution,grounding resistance and utilization coefficient are measured. Experiments showthat the current distribution of the electrode is uneven and the grounding current at the lower part of the electrode is much bigger than the upper part,but the stepvoltage is improved because the vertical grounding electrode transports the current into deep underground. Current distribution between the parallel grounding electrodes is influenced by both the shielding effect and the value of grounding resistance. At the same time,the accuracy of theoretical calculation is verified by the high consistency between the test value and theoretical calculation value of the utilization coefficient.