A procedure for diagnosis and condition based maintenance for power transformers

Power transformers are important and expensive components in electric energy networks. Because of the economic motivation, preventive tests and diagnosis are of benefit to predict fault conditions, optimize maintenance and increase reliability of power transformers. There is a large amount of academic and industry researches into transformer diagnosis and maintenance. Advanced diagnostic techniques and recently introduced online monitoring approaches for power transformers, provide the means to enhance the classical maintenance program. Therefore it is necessary to change from time based maintenance program to a condition based diagnosis procedure. In this contribution we introduce diagnosis and condition based maintenance programs for power transformers. This program, according to the current situation and periodical inspections of transformer, will suggest a procedure for performing diagnosis and maintenance. The condition based diagnosis process uses some of the current diagnosis methods (e.g. oil test, DGA, PD, etc.) to determine the condition of the transformer. In this process, we don´t use all of the diagnostic methods in the first step, but, rather we suggest some methods step by step based on the transformer condition.