Dielectric Properties and Fire Safety of Mineral Oil and Low-Viscosity Natural Ester Mixtures in Various Concentrations

Abstract

This paper presents the results of testing the electrical and fire properties of mineral oil and low-viscosity natural ester mixtures. Properties such as breakdown voltage, relative permeability, dispersion coefficient, conductivity, flash and burn point, and lower heating values were investigated in different concentrations of mixtures of the two liquids, as well as for the base liquids. To ensure equal humidity levels, the prepared samples of mixtures and base liquids were conditioned under identical climatic conditions, resulting in samples with similar relative humidity (9 ± 3)%. The obtained measurement results for mixtures of the two fluids were related to the values obtained for the base liquids and analyzed in terms of changes in electrical properties and fire safety when used as insulating liquids in transformers. The presented results are useful for supplementing knowledge on the possibilities of using dielectric liquid mixtures in high-voltage power devices, with to the aim of using mixtures as alternatives to mineral oil.