Remnant life estimation of power transformer based on IFT and acidity number of transformer oil

Abstract

Power transformer is a key asset in any electrical transmission or distribution network. As a significant number of the global power transformers have reached the end of their expected designed life, utilities have given more concern to transformer condition-based maintenance to extend transformer operational life span and to retain the highest viable efficiency of the asset. Transformer failure statistics indicates that most of the failures occur before power transformers reach their expected operational life. Statistics also show that the main cause of transformer failures is attributed to the deterioration of dielectric insulation due to transformer ageing which is highly dependent on accumulated effects of moisture, temperature, Oxygen and acids in transformer oil. When paper insulation exhibits severe deterioration, it loses its tensile strength and its capability to withstand electrical faults significantly decreases. Interfacial tension and acid number of insulating oil are correlated with the number of years in which a transformer has been in service and are used as a signal for transformer oil reclamation. This paper introduces a new, simple and effective fuzzy logic-based model to estimate the remnant life of a power transformer based on the values of interfacial tension and acid number of power transformer insulating oil.