Transformer oil

The complex nature of the material, the resulting difficulty in establishing significant tests for evaluation in reasonable time, and the varying conditions of use, have combined to make the study of oils used for the insulation and cooling of transformers a painfully slow process. It is the purpose of this paper to review some of the very extensive efforts made in this study and to draw at least tentative conclusions as to the present status and future possibilities of one of the most important materials in the design, manufacture, and operation of transformers.