Chemical progress on insulating oils

One of the most important researches on mineral insulating oil deterioration is that of J. C. Balsbaugh and his associates at M. I. T., sponsored by the Engineering Foundation -- American Institute of Electrical Engineers. J.C. Balsbaugh, A.G. Assaf, and W.W. Pendleton (1) described the results of recent studies. A summary of the subjects studied and the results obtained are listed below: a) The effect of temperature on the oxidation and electrical characteristics of an oil of the light cable oil class, 100 S.U.S. at 100°F. The mechanism of the oxidation reaction was found to be the same up to 95°C. (tests conducted in the presence of copper and paper). Above 95°C. the reaction was of a different mechanism, and resulted in an excessive deterioration of the paper present. b) The oxidation and electrical characteristics of a series of heavy cable oils, around 2000 S.U.S. at 100°F. having varying aromatic content. There did not appear to be any specific relation between the aromaticity of the heavy oils and their electrical stability as indicated by the change in conduction with absorbed oxygen. With one exception, however, electrical stability with respect to time of deterioration was improved with decreasing aromaticity as reflected by increasing degree of refining. c) The effect of limited amounts of oxygen on an aromatic-free oil of the light cable oil class, 100 S.U.S. at 100°F. It was shown that limited amounts of oxygen in the presence of copper, and copper and paper caused very high conductance losses. d) The oxidation and electrical characteristics of two pure hydrocarbons, cis-decalin, and hexadecane (cetane). Oxidation and electrical characteristics of the hexadecane gave results similar to the limited tests on the aromatic-free oil. During the oxidation induction period, extremely high conductance losses were noted for the small amounts of oxygen absorbed. Cis-decalin, on the other hand, exhibited very low conduction losses for the large amount of oxygen absorbed.