Framework for aging of composite insulators to assist asset management

This paper presents two technical frameworks that can be used to effectively monitor both ethylene propylene diene monomer (EPDM) and silicone rubber (SiR) composite insulators during their life in service, and provide a tool that assists asset managers decision making. The first framework, derived from a more general framework, links the mechanisms that govern composite insulator materials´ ageing on power lines with measurable material properties and is intended to be used to monitor composite insulators in service and in a laboratory environment. These diagnoses link knowledge of ageing of insulators in general with the needs of asset managers. Properties of materials that can be measured in order to identify ageing, and different techniques available as engineering tools for measuring these properties, on-line and off-line are presented. The second framework establishes definitions of four ageing states in relation to risk of failure, each of which a composite insulator will go through in service before its failure or replacement. Examples from EPDM and SiR insulators that were service aged at coastal environments are used to illustrate the proposed frameworks.