Quantitative study on the aging of kraft paper in vegetable oils

Interest in using vegetable oils as dielectric coolants in power transformers dates back to the early studies on linseed- and castor- based fluids as possible replacements of mineral oil. However, interest in vegetable oils was lost due to their high viscosity and their tendency to oxidize. But, in the early 1990s and due to environmental concerns, the interest in dielectric fluids based on vegetable esters re-emerged. As a result, two vegetable ester- based oils were developed, namely, BIOTEMP, developed by ABB, and FR3®, developed by Cooper Power Systems.