Field experience with transformer solid insulation ageing markers

In recent years, methanol has emerged as a chemical marker for assessing transformer cellulose insulation ageing. This brochure examines various aspects related to methanol, including progress in recent research, users’ experience with taking measurements on in-service transformers and the challenges faced with respect to the measurement of methanol in transformers and the interpretation of results.

A round-robin on the measurement of alcohols (methanol and ethanol) in laboratories showed that an analytical technique based on gas chromatography is robust and provides acceptable results. Many utilities around the world already measure methanol in their transformers. However, factors such as the wide range of cellulose/oil ratios and the variations in transformer design and loading patterns…