Читать книгу Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems - Группа авторов - Страница 53

The IFT value of insulating liquids provides important information for detection of impurities or polar contaminations in the oil. The poor value of the IFT leads to drop in the quality of the oil, which is caused by the generation of oxides and peroxides in the insulating oil during its service. The value of IFT is measured in accordance with the standard ASTM D971. IFT is determined by the differences of the interactions between the molecules of one fluid to another fluid [66]. It is also observed that the IFT of NEO is lower than that of MO because of the molecular structure of NEO, which contains unsaturated fatty acid chains and the moisture content present in the oil. The NEOs have variances in the fatty acid structure which differ in their carbon chain lengths and in the number of double bonds or unsaturation. IFT is a physical attribute that is closely associated with the molecular configuration. The number of unsaturated fatty acids and the length of the fatty acid hydrocarbon chain affect the IFT value and the tension also increases when the chain length increases.