Development of an integral criterion for evaluating the degree of aging of transformer oils

Abstract

The technical condition of the transformer oil affects the condition of the solid insulation, and therefore the residual life of electrical equipment, so it is important to study the aging mechanisms of the oil. The mechanism of transformer oil aging is studied using factor analysis of oil quality indicators, such as moisture content, acid number and dissipation factor tangent. Factors that have the greatest influence on the rate of oil aging have been found. In accordance with the found influence factors the permissible values of oil quality parameters of 110 kV power transformers with division by equipment tightness, oil brands and operating time have been determined. Oil aging models, taking into account the mutual influence of oil quality parameters, have been developed for transformers with different oil brands, type of oil protection and service life. An integral index, characterizing different aging processes of the oil, has been proposed. The criterion for evaluating the integral index of oil aging rates is calculated. © Published under licence by IOP Publishing Ltd.