Natural and accelerated aging of composite insulators

Composite insulators or nonceramic insulators (NCIs), as they are also known, represent a relatively new technology applicable to transmission line insulation. Although they have been used for the last three decades in many countries, several aspects regarding materials, design, applications, specifications, testing, maintenance and aging are not well established yet. This paper presents the results of a research project developed by CEPEL (a Brazilian Electrical Power Research Center) and some utilities together. It aims at performance evaluation of different NCIs submitted to accelerated and natural aging. The conclusions taken from the accelerated aging tests show the influence of insulator design, leakage distance and housing material on the electrical performance of different NCIs. The results of field investigation show some degradation that does not imply in reduction of electrical or mechanical properties of the insulators up to now.