Dry band formation on HV insulators polluted with different salt mixtures

Pollution flashover on high voltage insulators is a major problem for power transmission lines. It is a very complex issue due to many factors i.e. modelling and design difficulties, unknown environmental stress, non-uniform distribution of pollution on insulator surface and different pollution levels in different regions. The deposition of pollution layers on high-voltage (HV) insulator surface is the first stage of pollution flashover. The aim of this paper is to investigate the influence of dry band formation and its characteristics on HV insulators with different salt mixtures and variable pollution layer thickness. The non-uniformity of the contaminant distribution, wetting and drying process leads to the development and formation of multiple dry bands on the insulator surface. From the test results it is clear that the dry band formation is not uniform with different salt mixtures. COMSOL Multiphysics™ has been used to simulate an insulator surface to find the variation of dry band formation with applied voltage. In particular, this paper aims to obtain a better reproduction method of pollution layers deposited on insulators which is very important to improve the reliability of HV insulators installed near coastal regions.