Field and lab aging of EP compound arresters

Organic polymers, such as EPDM, by virtue of their very nature are susceptible to aging and degradation (weathering) when used for high voltage outdoor insulator applications. The very same flexible bonds that offer the advantages of polymers also make them vulnerable to aging and degradation. This paper presents the aging and degradation of 10 kV and 18 kV EP polymeric arresters removed after 10 years and 5 years of service respectively in Florida (FL). There is severe chalking and discoloration and alligatoring on the 10 year arrester. FTIR analysis showed major loss of various chemical groups, such as CH₂ and CH₃ above 95% in the alligatored part and up to 70% in the nonalligatored part. Similar but lesser magnitude changes were seen in the 5 year aged arrester. SEM micrographs of the field aged samples showed deeper cracks in alligatored portion compared to non-alligatored portion. Similar results, but of relatively lesser magnitude, were observed in the laboratory aging of arresters for a similar period.