Analysis of the Impact of Power Transformer Loading on the Transformer Oil Aging Intensity

Abstract

Operating temperature, which depends on the load of transformers, was analysed as a factor affecting the intensity of aging oils. The analysis results provided a quantitative assessment of the impact of transformer load on the drift intensity of oil indicators. In particular, the dependencies of the induction period duration (time during which the values of indicators do not change) and the values of oil indicators increments after 25 years of operation on the average transformer load for a given period were obtained. It has been established that formation of water-soluble acids (the most dangerous oxidation products) in oil occurs only in transformers whose average load has exceeded 50% during the last 13 years. Increase of transformer load from 10 to 50% leads to 3.5 times increase of organic acids content after 25 years of operation (from 0.029 to 0.102 mg KOH per 1 $g$ of oil). The obtained results allow using more advanced methods of transformer oils condition assessment (for example, trajectory method or methods based on regression models), but also forecasting their values.