Determining Power Transformer Maintenance Plan Using Three-Dimensional Risk Matrix

This paper presents the power transformer maintenance decision technique using a three-dimensional risk matrix to compound risk acquisition from technical condition assessment, impact factor, and economic index aspect into maintenance decision-making. The risk in terms of technical conditions and impact factors are evaluated using scoring and weighting techniques to convert data from various important criteria and physical test results into transformer risk. In addition, the costs that occurred in transformer life are analyzed by using the equivalent uniform annual cost technique to determine the economic service life and compare it with the transformer aging to define the economic risk factor. The obtained three risk factors are then compounded by using the three-dimension risk matrix pattern to identify each transformer's overall risk. Based on the overall risk, an appropriate maintenance plan was established to achieve maximum effectiveness in terms of reliability, availability, and economic benefit. The decision technique presented in this paper is applied to nineteen substation power transformers of various ages and load areas in the Central 1 area of Electricité Du Laos (EDL). The results showed that the decision model could successfully determine appropriate maintenance programs with the ability of systematic decision-making. Finally, the power transformer's maintenance strategy can be effectively managed.