The Condition of Solid Transformer Insulation at End-of-Life

The present report details the issues around the physical EoL parameters, discusses unknown correlations of aging records with aging status of solid insulation, and unveils and describes related gaps in knowledge. Uncertainties are generated and associated to monitoring data, oil sampling challenges with temperature and related water, acids, furanic compounds partition, mainly 2FAL (2-Furfural) occurrence dependence on paper thermal upgrading and loss due to oil change and/or treatments, etc. Answers to a questionnaire from 44 utilities give insight to today’s EoL assessment practices worldwide. Elaborating on the physical properties of aging cellulosic insulation along with the postulation of safe operation, work is proposed to be undertaken in order to answer the questions transformer…