Anomalous Conduction as a Cause of Dielectric Absorption

Abstract

The paper describes a series of experiments on the fundamental electrical properties of a number of waxes and oils, such as are used in composite high-voltage insulation. Particular attention has been directed to dielectric absorption as the origin of dielectric loss and the probable cause of deterioration and short life. The relation of the properties of the constituent parts to the properties of mixtures has been examined, with special reference to purification methods and the influence of small amounts of impurities. The studies have also afforded opportunity to test the validity of certain existing theories of absorption and loss. The method of experiment is the recording of short time absorption curves by means of the string galvanometer. Charge and discharge curves have been traced from a small fraction of a second following the beginning of charge or discharge, these curves having been brought much nearer to their beginnings than any heretofore recorded. It is this region near the beginning of these phenomena, which is most important in its bearing on dielectric loss. The principal results are summarized at the end of the paper, among the most striking being: (a) The extensive evidence that dielectric absorption is purely a conduction phenomenon; (b) The conductivity of dielectrics is highly anomalous in character, sometimes increasing, sometimes decreasing with increases in voltage and temperature. Absorption always follows the conductivity in these changes.