Power transformer aging and life extension

Power transformer is a critical and expensive asset for any power utility. Many transformers around the world are serving close to or beyond their designed life. There is an increasing focus on maintenance and life extension of existing transformers to maximize the return on investment. Transformer failure statistics exhibit that most of the failures have occurred before reaching their rated life. Transformer failures due to dielectric problems are reported as high as 75%. Furanic compounds presence in oil provide an indication of solid dielectric deterioration. It is important to identify the deterioration stages of dielectrics and its degree of sensitivity towards aging. Ageing is also strongly dependent on temperature, oxygen and water levels in the transformer. The transformer life can be maximized by controlling these variables. This paper presents a fuzzy logic based approach to estimate the age of a power transformer using key indicators such as moisture and furanic compounds.