The Dielectric Losses in Impregnated Paper

Accurate measurements have been made of the electrical and other physical properties of 10 insulating oils, of a single grade of wood pulp paper, and of the paper when impregnated with each of the oils. Short time charge and discharge curves under continuous potential have thrown further light on the anomalous conduction as found in oils, and permit the separation of the total dielectric loss into two components. Of the total increase of the loss found in impregnated paper, over the separate losses in oil and in dry paper, one component is proportional to the effective conductivity of the oil. The other component, due to reversible absorption, is, for a given paper, a definite function of the free ion content of the oil as indicated by the product of the conductivity by the viscosity. These relations hold over the entire ranges of type of oil and temperature under study. The product of conductivity by viscosity is proposed as a measure of the ``electrical purity´´ of an oil used for impregnation. The simplicity of the relations shown suggests that an extension of these studies to other grades of paper should make it possible to predict accurately, from the separate properties of paper and oil, the electrical behavior of any grade as impregnated with any type of oil.