Insulation Performance and Microstructural Mechanism of Self-Extinguishing Fluorinated Silicone Oil

Traditional mineral oils are widely used as liquid insulating media in power transformers, and the search for new liquid insulating media is crucial due to their limited fire resistance and biodegradability as well as the scarcity of fossil fuels. Two possible alternative media, natural insulating ester and silicone oil, have been proposed, but the relevant performance index parameters of the two need to be further optimized, and there are still more challenges to be faced when they are put into operation in transformers. In this article, the insulating properties of three new self-extinguishing fluorinated silicone oils are investigated theoretically and experimentally and their application potentials are evaluated. The results of the frequency breakdown experiments show that the insulating properties and stability of hydrogen-containing silicone fluoride oils are better than those of hydroxy silicone fluoride oils and methyl silicone fluoride oils. By constructing molecular models of the three different types of silicone fluoride oils and analyzing the bond lengths, HOMO-LUMO energy level differences, and the area of distribution of the electrostatic potentials, the results indicate that the uniformity of the electron distribution of the hydrogen-containing silicone fluoride oil molecules is superior to that of methyl silicone fluoride oils than to that of hydroxy silicone fluoride oils. The results show that due to the molecular electron distribution uniformity of hydrogen fluorinated silicone oil being better than that of methyl fluorinated silicone oil and hydroxyl fluorinated silicone oil, this leads to a difference in polarization ability between the materials, so the hydrogen fluorinated silicone oil shows better insulating properties, which provides a certain reference for the research of new liquid insulating media that can replace mineral oil.