Comparative analysis of life estimation and reliability of power transformers

Due to large amount of power transformers and the need to reduce process downtime in the paper making mill, a life assessment of these power transformers is necessary to ensure continuity of supply. Several models have used to estimate the life time and reliability of transformers but in this paper, Furan analysis and Weibull distribution method is utilized and compared for ten representative transformers. From the furan analysis, the degree of polymerization (DP) in each of the transformer oil was calculated using Chendong's formula. The results were then used to determine the used life of the transformers. Then Weibull distribution method was used to determine the reliability and service life of each of the transformers. The reliability was then used to calculate the remnant life of the transformers. The Weibull analysis gave reliable results and the discrepancy in the furan analysis method shows that proper maintenance e.g. oil purification can increase the life expectancy of transformer. It is therefore recommended not to use only the Furan method when estimating the life of power transformers.