Vegetable oils for liquid-filled transformers

Several billion litres of transformer oil are used in transformers worldwide. To meet the challenges posed by environmental concerns, fully biodegradable vegetable oils have been developed for use in electrical equipment, particularly in transformers. Against this background the author discusses the development of vegetable oils for transformer use, their biodegradability, decomposition products, functional life test, fire hazard tests and the special challenges presented by cold weather. Further exploitation of these fluids for use in capacitors and cables needs further study and tests.