Aging of pressboard in different insulating liquids

Abstract

Today, the transformer industry uses alternative insulating liquids more and more. Possible alternatives are vegetable esters such as rape seed, soy bean or sunflower oils or synthetic esters. The aim is to replace the flammable and environmentally harmful mineral oils. Another advantage of these liquids is the higher water solubility, which is claimed to be responsible for a reduced aging rate of cellulosic insulation compared to mineral oil.