Multifactor aging mechanisms on the surface of model post insulators

The authors discuss multifactor aging of the surface of post insulators made of epoxy resin, which are stressed simultaneously by high electric field strength and condensation (moisture) layers. Test setups and procedures developed for the application of these stresses and relevant diagnostic tools are presented. In order to simulate indoor conditions special test setups and test procedures based on condensation and cold-fog environment are presented. Investigations show that the appearance of first surface aging effects depend on the characteristics of the droplet layers and the partial field strength stress in the vicinity of the electrodes. The results also show that, for post insulators in service, the lifetime of the surface of the insulation will be in an acceptable range if condensation with low pollution and low electrical field strength stress are present on the surfaces