Outdoor HV composite polymeric insulators

HV composite polymeric insulators are being accepted increasingly for use i n outdoor installations by the traditionally cautious electric power utilit ies worldwide. They currently represent similar to 60 to 70% of newly insta lled HV insulators in North America. The tremendous growth in the applicati ons of non-ceramic composite insulators is due to their advantages over the traditional ceramic and glass insulators. These include light weight, high er mechanical strength to weight ratio, resistance to vandalism, better per formance in the presence of heavy pollution in wet conditions, and comparab le or better withstand voltage than porcelain or glass insulators. However, because polymeric insulators are relatively new, the expected lifetime and their long-term reliability are not known and therefore are of concern to users. Additionally they might suffer from erosion and tracking in the pres ence of severe contamination and sustained moisture. This leads to the deve lopment of dry band arcing that under certain circumstances could lead to f ailure of polymer insulators. In this paper a review is presented of the re cent performance experience of HV composite polymeric insulators in outdoor service, testing methods, aging, the ranking of the materials, the role of fillers, the role of low molecular weight components present in the insula tors, the mechanisms responsible for the loss and recovery of hydrophobicit y, one of the most important properties of polymers, the mechanisms of fail ure, detection of faults, type and quantity of natural contaminants, effect s of exposure to rain, hydrocarbons, stationary air and wind, various metho ds to optimize the electrical performance and a relatively new method for e valuating the performance status of polymeric insulators in the field.