Dielectric properties of mixtures between mineral oil and natural ester

From the experimental results some conclusions can be drawn as follows. The properties of mixture between mineral oil and natural ester from palm oil in general strongly affected by the ester content. Increasing the ester content significantly enhance the dielectric breakdown. The increase of the ester content also resulting in a higher the losses factor especially at temperature of 100degC. Viscosity and density of the mixture slightly increased with the ester content but significantly decreased with temperature. The acidity of the oil mixtures almost linearly increased with the ester content. Taking into account the requirements from standard, the mixture of natural ester from palm oil and mineral oil with ester content of 50% is considered as good enough to be used as a high voltage insulating liquid.