Contamination performance of high voltage outdoor insulators in harsh marine pollution environment

This paper deals with an experimental investigation comparing the contamination performance and surface degradation of outdoor insulators made from different polymeric materials. The tested insulators included silicone rubber (SR), ethylene propylene diene monomer (EPDM) and high-density polyethylene (HPDE), which were used for reference. To replicate typical harsh marine pollution environments, a modified solid layer contamination deposition method was used. In this method, conditions similar to those existing near shorelines exposed to saline and acid spray during winter and early spring were reproduced. The tests were carried out in acidic and normal cold fog. The physico-chemical changes and electrical parameters were measured during the tests to characterize the performance of each insulator. The analysis showed that the electrical performance of the insulators was significantly affected by the combined application of saline contamination and acidic cold fog. However, during clean cold fog application, the insulator material showed localized surface degradation while there was no evidence of serious dents and cracks. Saline contamination with normal cold fog generated a reduction of flashover voltage equal to 40%. This reduction was more pronounced in acidic fog conditions - 85%. The scanning electron microscopy (SEM) and hydrophobicity results showed that surface degradation is more strongly correlated with acidic cold fog contents than that of normal cold fog. It was found that SR insulators perform better than EPDM and HPDE in harsh environments.