DETERMINATION OF PHENOLIC-TYPE ANTIOXIDANT ADDITIVES IN FRESH INSULATING OILS BY IR SPECTROMETRY ON A LIQUID EXPRESS ANALYZER ATTACHMENT

Abstract

For more than 120 years, transformer oil, derived from oil, has been most widely used as an insulating and heat dissipating medium in oil-paper insulated electrical equipment. During operation, under the influence of such factors as elevated temperature of the windings, electric field, contact with air oxygen and metal parts of the equipment, the oil is oxidized resulting in the deterioration of its electrical insulation properties and creating the risk of failure of expensive electrical equipment. In order to slow down the oxidation process and extend the life of the oil, the inhibiting additive ionol is added. However, in previously published works we showed that the additive ionol itself also undergoes decomposition with the formation of other phenolic compounds, which presence acts as an additional indicator of intensive aging of the liquid dielectric. Therefore, it is advisable to control in fresh transformer oils not only the content of ionol itself but also the presence of its degradation products showing similar inhibitory properties. A method of quantitative determination of ionol (2,6-di-tret-butyl-4-methylphenol) as well as 2,6-di-tret-butylphenol is proposed in the present work. The method of analysis is based on the IR spectrometry using a liquid express analysis attachment. The proposed method has a number of advantages over other methods, including standardized methods, i.e. speed; simplicity; safety, since chemical reagents are not required; low cost of consumables.