In-service diagnostic of polymeric insulators exposed to severe contamination

In Mexico since 1995, polymeric insulators have been used in transmission lines exposed to severe contamination. Insulators from different manufacturers have been installed; however, some of them have failed during their early operation years. Consequently, since 2003, in-service diagnostic has been periodically carried out to identify high risk insulators, by using the visual corona and electric field measurement techniques. In this paper, the most important results obtained from different inspections performed in-service to polymeric insulators on Mexican transmission lines are presented. These results show that the visual corona and electric field measurement techniques can be used to identify high risk polymeric insulators prior to failure.