防雷接地体性能改善及接地电阻分析计算

Performance Improvement of LightningProtection Earthing Electrodes and Analysis and Computation of Earthing Resistance

结合雷电防护工作中的经验和实例,分析防雷接地体的特性。结果表明：降低接地电阻,主要是通过降低接地体的接触电阻和散流电阻;增加接地体所围面积对接地电阻的减少有利;应充分考虑复合接地体形状和接地网内屏蔽效应对接地电阻的影响;接地体周围的土质、埋设深度和季节变化都影响土壤电阻率。接地极沿接地体网边缘设置,网内接地极要稀疏布设,接地极的长度一般不相等,常用接地体埋设深度在1.5～3.5 m之间,北方地区在冻土层以下。可采用性能稳定的降阻剂和在接地体周围更换土壤电阻率低的土质,要使接地电阻达到要求的同时减少成本。

On the basis of the experiences and examples from thunder and lightning protection practice, the characteristics of lightning protection earthing electrodes are analyzed. The results show that reducing earth resistance is mainly through reducing the contact resistance of earthing electrodes and dispersed resistances; increasing the encircled area of a earthing electrode is advantageous to the reduction of earthing resistance; the shapes of compound earthing electrodes and the influence of screening effect in the earthing grid on earth resistance should be fully considered; the soil resistivity is affected by the soil property around the earthing body, the burying depth of earthing electrodes, and seasonal variation. The earthing electrodes are arranged along the edges of the earthing grid, and the electrodes are distributed sparsely in the grid with different earthing electrode lengths. Generally, the burying depth of a commonused earth body is between 1.5 m and 3.5 m, below the frozen earth level in North China. The frictionreducing agents with stable performance and the soil with low soil resistivity can be used around earth bodies so to reduce costs while filling the requirement for earth resistance.