季节因素对发变电站接地系统安全性能的影响

季节因素将影响地网的安全性能，导致地网的接地电阻、接触电压和跨步电压的改变。采用数值计算方法分析了季节因素对地网安全性能的影响。雨季将导致地网接地电阻及地表跨步电压减小，但有可能导致接触电压增加。冰冻季节将导致地网接电阻增加，如果冰冻层的电阻率很高，接地电阻将增加到原来的１．７～３．０倍；冰冻季节还导致接触电压和不电压增加。当冰冻层厚度超过地网的埋深时，导致地风遥大幅度下降，危害人身安全。在高寒冰

INFLUENCE OF SEASONAL FACTOR ON SAFETY OF GROUNDING SYSTEM

The seasonal factor affects the safety of grounding system, and causes changes in the grounding resistance, the step and touch voltages on the ground surface above the grounding system. The influences of seasonal factor on the safety of grounding system were analyzed in numerical method. In the raining season, the grounding resistance is reduced; but the touch voltage is probably increased. Hence, the influence of raining season on the safety must be considered. In the freezing season, the grounding resistance is increased, as 1.7 to 3.0 times as the normal value when the resistivity of frozen soil is very large. When the thickness of frozen soil layer exceeds the burial depth of grounding system, the grounding resistance, and the step and touch voltages would be increased, and the safety is largely decreased. In highly frozen region, the best solution to ensure the safety is to choose a suitable burial depth which exceeds the thickness of frozen soil layer.