The natural contamination of XP-70 insulators in Shenzhen, China

Abstract

Equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD) are two basic parameters for the coordination of outdoor insulation and classification of pollution severity. Type XP-70 is usually selected as the test object for classification of pollution distribution in China. In this study, 113 transmission towers representing typical distribution of Shenzhen, China, are selected as observation sites for XP-70 insulators, which have a total of four discs. The ESDD, NSDD and the ratio of NSDD to ESDD for XP-70 insulators with the exposure times of one, two and three years are measured. The following aspects are compared: the difference of natural contamination characteristics of four XP-70 insulators at the same place, the difference of natural contamination characteristics of XP-70 insulators in five different regions (the coastal region, the highway region, the suburb region, the mountain region, and the urban region), and the difference of natural contamination characteristics of XP-70 insulators after years of contamination exposure. The results are as follows: the difference between the ESDD and NSDD of the upper surface of the four discs is significant, whereas that of the lower surface is not. The contamination in the coastal region is the most severe whereas that in the mountain region is the lightest. For the rest three regions, the difference is negligible. The ESDD and NSDD of XP-70 insulators become saturated at different times. We also found that presence of the vulcanized silicone rubber (RTV) coating will significantly increase the ESDD and NSDD of the insulators.