An experience in oil testing of medium voltage transformers

An asset management tool using a simple technique for determination of maintenance priority level of medium voltage transformers is presented in this paper. Case studies during implementation of the decision tool on transformers with a decreased in oil quality are also discussed in this paper. Among the investigated cases, a transformer with a declined breakdown voltage and an excessive production of combustible gasses has become an interest for further examination. The formed combustible gas in the transformer tank activated the gas fault protection system, hence interrupting the electricity supply. The transformer status has been categorized into priority level 1 and an immediate maintenance was carried out accordingly.