Suitability of Alternate Fluids as Transformer Insulation - A Comprehensive Review

Mineral oil (MO) had been in use in transformers for over a century. However, with the ever-increasing upsurge in voltage and power levels coupled with the depleting reserves of fossil fuels led researchers all over the globe to tread down the uncharted territory of finding suitable alternatives to mineral oil as a transformer insulation. Several types of research have been conducted since the late 90’s to determine the viability of these alternate fluids. Esters among several other fluids have evolved as a suitable substitute for mineral oil insulation mainly due to its environment-friendly nature and ability to replenish in large quantities. Substantial research is been carried out in several countries like USA, UK, China, Japan, Australia, Brazil, and India. This article is a compilation of several recent research works in the field of alternate fluids as transformer insulation which promises to help not such budding researchers but also utilities dealing with such fluids. It also gives an insight into the future trends in research involving such fluids. Due to the paucity of scope and space, only a few seminal contributions in this field have been included.