冻土冲击特性的试验研究

我国西部地区的输变电工程经过多雷的永冻土地区，了解冻土的冲击特性是输变电工程雷电防护的基础。该文通过试验方法对冻土的起始击穿场强进行研究，并对温度、水分、含盐量等因素对冻土的起始击穿场强的影响规律进行探讨，同时结合土壤导电机理对试验结果进行了初步的解释。以水平接地体为例说明温度对冲击接地电阻的影响。试验表明，土壤的起始击穿场强随着温度、含水量以及含盐量的升高而降低；接地体的工频接地电阻和冲击接地电阻随温度的降低而增加，冲击系数却随着温度的降低而降低。

Experimental Study on Impulse Characteristics of Frozen Soil

Many power transmission projects in western region of China pass through the permafrost with frequent thunders, so understanding the impulse characteristics of frozen soil is the basis of lightning protection of power transmission projects. An experimental method was used for studying the initial electric breakdown field intensity of frozen soil and the main factors influencing the impulse characteristics of frozen soil such as temperature, water content and salinity were analyzed. In conjunction with the conductive mechanism of soil, the experiment results were explained initially. A horizontal electrode was taken as an example to analyze the impact of temperature on impulse grounding resistance. The experiments show that the initial electric breakdown field intensity of the soil decreases with the increase of the temperature, moisture and salinity; the power frequency grounding resistance and impulse grounding resistance of the electrode increase with the decrease of the soil temperature, but the impulse coefficient decreases.