中文摘要：

沙尘暴过境产生电荷分离,形成风沙电场,干扰着无线电通讯,并在导线上产生高电位,可能直接导致电力系统外绝缘失效,影响着沙尘环境地区输电的发展。为研究沙尘中大粒径对放电过程的影响,利用石英砂来模拟沙尘暴天气,在测定模拟沙尘的粒径和体积分数的基础上,对比分析了空气与沙尘中的击穿电压、放电路径对沙尘与空气的选择概率,并分析了大沙粒对伏秒特性和放电通道的影响。实验结果表明：1）粒径较大（直径〉100μm）的沙粒对放电的发展有促进作用,但当粒径〉2 mm时,这种作用不是很明显;2）粗沙比细沙击穿的平均时间要长,且击穿时间较为分散;3）粗沙中的放电通道相对较宽。经分析认为沙尘表面光电离、沙尘中电场畸变等作用是大沙粒有利于放电发展的主要原因。

英文摘要：

In order to understand the effect of sanddust sizes on discharge development,quartz sand is applied to imitate dust environment.By measuring sanddust particle sizes,volume fraction of sanddust in simulative sandstorm,we comparably analyzed the breakdown voltage in air and sandstorm,the percentages of the discharge path in mist or air,and effect of large sanddust particles on U-t Characteristics and discharge channel in a non-uniform field,at atmospheric pressure.The results show that：（1） Sanddust particles with diameter 100 μm are propitious to discharge development;but when the diameter 2 mm,the positive effect of sanddust on discharge development is not obvious;（2） The average time of breakdown under sanddust with the diameter of 2.15 mm is greater than that under sanddust with the diameter of 0.12 mm,and the time of breakdown under sanddust with the diameter of 2.15 mm is more scattered;（3） Discharge channel under sanddust with the diameter of 0.78 mm is relativly wider. The mechanism such as photoemission from the surface of sanddust,electric field distortion around sanddusts offers explanations for the positive impact of large sanddusts on discharge development.