Overrefined Oils in Power Transformers

Insulating oils ordinarily used in tramsformers have high stability toward oxidation, and much effort has been directed toward reducing the oxygen absorption qualities of such oils. Contrary to usual practice, however, the tests reported in this paper were made with a readily oxidizable or ``overrefined´´ oil on the basis that the oxidizing qualities of this oil will maintain, automatically an inert gas above the oil and thus reduce explosion hazards. On the basis of these tests, it is said that transformers equipped for restricted breathing can be operated with overrefined oil over long periods without servicing as far as the oil is concerned. Among the chief disadvantages of such oil is its high cost?? approximately twice that of present commonly used oils.