Development of a low viscosity insulating fluid based on vegetable oil

Environmental considerations demand alternatives for the current mineral oils used in many electrical equipment, such as transformers. Because of their excellent biodegradability and non-toxicity, relative to petroleum derived products, the use of the vegetable oils is on the rise as insulating and heat transfer liquid in electrical devices. In addition such natural esters have a favorable lower flammability, but their viscosity and low temperature behavior is not well suited to applications in cold climate and/or with natural cooling system. That is why a new insulating fluid, based on modified vegetable oil, has been developed that presents properties very similar to those of the standard insulating mineral oils used in transformers. This paper presents the formulation of this low-viscosity ester fluid, and it reports the results of a field experimentation carried out to assess the behavior of the fluid in real conditions.