FMECA analysis for the assessing of maintenance activity for power transformers

A serious failure of a large power transformer can generate substantial costs for the transport to factory, repair and financial losses resulting from power interruption. Therefore, utilities have a clear incentive to assess the actual condition of high voltage transformers, with the aim to minimize the risk of failures and avoid forced unexpected outages. Special attention in this respect is given to large transformers. In this paper, a general FMECA for outage causes of 220 kV power transformers is presented, including the local and final effects, and recommended actions to avoid these outages. Assignment of risk priority numbers to the various outage causes, which might occur at this voltage level, are carefully considered.