Influence of the profile on the performance of porcelain insulators installed in coastal high voltage networks in the case of condensation wetting

The performance of two fog-type porcelain insulators is investigated in the case of condensation wetting and uniform as well as non-uniform contaminant distribution. Both insulators have been employed simultaneously on the same transmission line poles and exceed the minimum required creepage distance. However, their field performance was remarkably different. The analysis performed indicates that, in the case of condensation, the total creepage distance is exposed to wetting, including the parts that are considered ´protected´ along the fog-type profile. In addition, these parts tend to accumulate more pollution, resulting in an inferior insulator performance. Consequently, for the specific environmental conditions, in addition to the creepage distance, the insulator profile is a parameter that greatly influences the service performance and therefore must also be considered in the selection of an insulator.