Prerequisites for transformer lifetime modeling towards a better understanding

The transmission transformer represent a significant asset in the electrical network. The transformer is expensive to manufacture and it is costly to replace. The cost of the transformer replacement is approximately 4 million EURO which is larger than the average component replacement activity. Therefore it is desired to make the replacement both timely and smooth to reduce unnecessary costs. Life time modeling is a tool for achieving such cost efficient replacements. This paper highlights the prerequisites for the transformer lifetime modeling. The lack of statistical failure data and a method for an overall condition assessment are identified as main issues. Furthermore, this paper presents one approach for transformer lifetime modeling based on Bayesian statistics which combines the expert opinion with the failure data in order to model the failure rate. This paper also suggests that the subjective information from the expert can be evaluated by the use of the analytic hierarchy process to achieve quality assurance. The overall objective of this paper is to present the research within the RCAM research group of transformer lifetime modeling and to enhance the understanding of the topic.