Alternative electrical insulating fluids in power transformers

Mineral oils are traditionally used in transformer insulation systems. As they are uneasily biodegradable, they have negative influence on environment, when transformer failure happens. There are also alternative electrical insulation liquids, which may help in some areas, however their properties may not fulfill the all requirements. This paper is comparing properties of these alternative insulation liquids with regards to its application in service. It is shown that vegetable oils cannot be directly used as a supplement of mineral oils, hence it has to be considered during transformer design. A simple simulation of electrical field distribution is presented to compare alternative fluids to a typical representative of mineral oils.