Abstract: “An efficient intelligent system (FUZZY LOGIC) for the power transformer residual life assessment is presented in this paper. In the fuzzy method, different inputs and one output is used, that strictly depends on the number of membership function and their rule base and the type of the defuzzification method. The residual life of the transformers greatly influenced by the condition of the transformer insulation system. The insulation of winding de-teriorates during the normal ageing of the transformers. Paper insulation that contains cellulose molecules degrades due to heating or electrical breakdown dissolved in the transformer oil. Hence, the analysis of the Transformer oil gives correct evidence of variation in the property of the winding insulation during operation. Deterioration in transformer oil-paper insulation decreases both its electrical and mechanical strength that influence the age of the transformer. This paper presents a fuzzy logic method that has been implemented on thr”

Keywords: Transformer oil, Condition Monitoring, Ageing, Parameters of transformer oil, and fuzzy logic controller.