Design and test experience with natural ester fluid for power transformers update

Natural Ester seed oil is a biodegradable fluid that is increasingly being used as a replacement for mineral oil and for high temperature flashpoint liquids, including silicone and RTEMP. Considerable studies have been conducted to investigate heat aging performance of cellulose, electrical contact, thermal stability, dielectric strength, moisture sensitivity, and cold temperature performance. A series of reports presents a summary of work that has been completed to date and examines initial customer experience with the use of natural esters in real transformers. The work updated from 2006 contains both new transformers and retro-fills in distribution and power transformers as well as step voltage regulators and switchgear.