引外接地装置连接线的均压优化措施

Measures for Optimized Voltage Blance Along Connection Line to External Grounding Device

当引外接地体距主接地网较远时,其与主接地网的连线可能会对接地系统的整体接地电阻及沿线的跨步电位差等产生影响。基于电磁场数值计算方法建立接地网及引外接地的分析模型,通过仿真计算,研究连接线材质、数量、埋深等对接地电阻、跨步电位差等的影响。由计算结果可知,连接线导电性越好、埋设越深、数量越多、则连接线附近的跨步电位差越低;当连接线的间距与其埋深一致时,连接线附近的跨步电位差最低;采用绝缘线作为连接线并不能有效降低其附近的跨步电位差。当土壤电阻率较高时,建议使用铜材连接引外接地网,连接线埋深和间距均以1 m为宜。研究结果为有效选择引外接地连接方式、保障人员安全提供了技术参考。

When the external grounding device is far away from the main grounding grid, the connection line to the main grounding grid may affect the overall grounding resistance and the step voltage along it. So we set up a model of the ex- ternal grounding device and the main grounding grid based on the electromagnetic numerical method. Then, we simulated the effects of the material, quantity, and depth of the connection line on the grounding resistance and step voltage. It can be seen that the better electrical conductivity, the more number, the greater depth of the connection line, and the lower the step potential will be. The minimum step voltage can be achieved if the distance between two connection lines is equal to the depth of them. Using insulated wires as the connection lines cannot reduce the step voltage near them. If the resistivity of the soil is high, it is suggested that the copper conductors should be used with the depth of 1 m and the space of 1 m. The research results provide a technical reference for selection of connection mode of the external grounding device to guarantee personal safety.