Fire resistant natural ester dielectric fluid and novel insulation system for its use

Insulation systems for electrical power and distribution transformers are being re-evaluated based on total owning cost from both economic and risk exposure perspectives. A developed high fire point dielectric fluid, based on natural esters, has superior safety, environmental, and health properties compared to current dielectric fluids. An insulation system developed for this fluid addresses the lower inherent resistance of esters to oxidation. Accelerated transformer life testing compares transformers using standard mineral oil to those with the natural esters dielectric system. Results of these accelerated life tests show the ester fluid to be suitable for transformer use and suggest the possibility of extended insulation life compared to mineral oil systems.