Abstract: The present invention comprises a mixture of hydrocarbons having a well-defined chemical composition that is suitable for use as a dielectric coolant in electrical equipment in general, and specifically in transformers. The dielectric coolants of the present invention are particularly suited for use in sealed, non-vented transformers, and have improved performance characteristics, including decreased degradation of the paper insulating layers, as well as a greater degree of safety and environmental acceptability. The present dielectric coolants comprise relatively pure blends of compounds selected from the group consisting of aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

Abstract: An electrical oil having reduced gassing tendency includes a major amount of a paraffinic or naphthenic basestock and a blend of certain hindered phenols, especially a blend of 2,6-di-t-butyl phenol and 2,6-di-t-butyl cresol. A further enhanced gassing tendency can be provided to the electrical oil by including a tolyltriazole derivative.