Large Power Transformers for Alternative Insulating Fluids

In times when personal safety and environmental protection become more and more
important, the usage of alternative insulation fluids is demanded in large power transformers. The
reduction of pollution risks and fire loads are significant goals for new transformers. Due to their
biodegradability and high flash point properties, ester fluids are becoming potential substitutes for
mineral oil. Alternative insulation liquids are produced by several companies, and they are
frequently used in distribution transformers. To operate power transformers successfully with
these alternative insulation liquids a number of issues must be resolved through extensive
investigations. Stability of transformer materials and other critical properties have been studied.
This paper shows how the alternative insulation liquids can be compared with conventional
mineral oil and to each other