Study of the dielectric properties of vegetable oils and their constituents

This paper deals with the analysis of perspective and environmentally-friendly electrical insulating liquids for electrical engineering. In the experimental part, dielectric properties of the most common vegetable oils were analyzed and compared with those of their constituents converted from triglyceryl esters to methyl esters: soybean oil, sunflower oil, rapeseed oil, peanut oil, cottonseed oil on one side and methyl oleate and methyl laurate on the other side. Dielectric properties were measured using the high-resolution Novocontrol Alpha-A Frequency Analyzer in the frequency range 1 Hz-10 MHz in the temperature interval 243 K-363 K. The lowest value of dielectric constant of natural oil (2.50) was exhibited at 363 K by peanut oil. Methyl oleate, an oil component which is usually present in large quantities, exhibited the value of dielectric constant equal to 3.23.