中文摘要：

利用位于北京市西北的自然积污试验站，研究了交流与直流电压下复合绝缘子和XP-70、XWP-70型瓷绝缘子的积污特点及积污量关系。在该站条件下，不同绝缘子污秽差异主要在绝缘子下伞面；交流电压下，积污期内复合绝缘子上伞面积污速率略高于瓷绝缘子上伞面，下伞面积污速率是瓷绝缘子下伞面的2倍以上。复合绝缘子下伞面的直流与交流积污比〉5,瓷绝缘子下伞面的直流与交流积污比〉10。大、小雨量下绝缘子下伞面受到两种不同方式的自清洗。复合绝缘子下伞面自清洗略受憎水性影响而削弱。直流与交流电压下，积污3a与积污1a的复合绝缘子下伞面污秽比值分别约为2．2和1．4，上伞面污秽相差不大。

英文摘要：

A natural pollution was tested to study the pollution and self cleaning characteristics of composite insulators and porcelain insulators （type： XP-70, XWP-70） energized with AC and DC voltage. Under the station＇s con- dition, pollution differences between different insulators and different stresses mainly appeared on the insulators＇ under-surfaces. During the main pollution period, upper-surface pollution accumulation rate of composite insulators was slightly higher than porcelain insulators＇, while the under-surface pollution accumulation rate of composite insu- lators was 2 times as much as porcelain insulators＇ , under AC stress. The under-surface pollution ratio between DC stressed and AC stressed composite insulators was more than 5. For porcelain insulators, this ratio was 10. Pollution composition of insulators under DC and AC stress was analyzed. Two kinds of insulator cleaning processes by rain were observed in high and low precipitation. Self cleaning of composite insulators under-surface was slightly hindered by hydrophobicity. The upper-surface pollution ratio between 3-year exposed and 1-year exposed composite insulators was about 1, while this ratio for under-surface under DC and AC stress were 2.2 and 1.4, respectively.