接地体附近导体对土壤中冲击电势分布的影响

Influence of adjacent conductors to the grounding device on the distribution of transient potential rise in the soil

模拟实际冲击接地实验的构架,采用时域有限差分(FDTD)方法建立计算模型,计算了雷电流冲击下接地体附近土壤中的冲击电势分布情况。计算结果表明:接地体周围土壤中存在的其它金属导体,将改变土壤中的电势分布,导致附近导体与接地体之间的电位差增大,而且,该电位差随土壤电阻率的增大而增大,与附近导体的形状体积也有关。接地体周围土壤中其它金属导体可能使得在所谓的安全距离上的安全裕量减少。

Simulating the impulse grounding experiment structure,the finite-difference time-domain（FDTD） calculation model is built,and the transient ground potential rise around the grounding conductor is calculated.Calculated results show that the adjacent conductor changes the distribution of electrical potential in soil,and leads to an increase of the potential difference between grounding conductor and adjacent conductor.In addition,the larger the soil resistivity is,the larger the potential difference is,and the potential difference is related with the shape and volume of the adjacent conductor.In conclusion,the conductor in the soil close to a grounding device decreases the safety margin at the so-called safety distance.