On the Evaluation of Conductivity of Mixtures of Liquid Dielectrics

A few formulas available for calculating the conductivity of combinations of solid dielectrics could also be used to evaluate the conductivity of mixtures of liquid dielectrics. However, they have certain limitations in the sense that they can only be used over a limited range of volumetric proportions, particularly so when one of the liquids in the mixture is highly lossy. In this paper, formulas are proposed, which result in predictable values that are in conformity with the measured values over a comparatively wide range of volumetric proportions. The authors have derived formulas elsewhere for predicting the loss factor and dielectric constant of a mixture of two low-loss liquid dielectrics. In this paper, a mixture of two liquids, one of which is highly lossy, is also considered. All measurements have been made on three typical mixtures consisting of transformer oil as base and cottonseed oil, castor oil, and ethyl alcohol (ethanol) as additives.