Field experience and pollution monitoring of composite long rod insulators

The Queensland Electricity Commission (QEC) has 16 years of field experience with various types of composite insulators on 110 kV to 275 kV transmission lines. Most of the insulators were first generation composites installed in clean and contaminated environments. In heavily contaminated areas, various forms of damage to the sheath and sheds were observed and a number of insulators flashed over. These failures have also been experienced in other parts of the world. This paper describes field experience with composite insulators and a leakage monitoring program that was initiated to evaluate the new generation of composites. For the monitoring program, a sensitive high voltage leakage current monitor was developed and a highly contaminated test site was selected for testing these insulators. Five long rod insulators were monitored over a two year period: 2 ethylene propylene diene monomer insulators; and 3 silicon rubber insulators, and comparisons were made with a string of ceramic insulators