Transformer life management bushings and tapchangers

Transformers are important components in electrical power systems and represent very large investments. The large investment in the electrical power system infrastructure with transformers was made in the 1960s and early 1970s. A significant part of the transformer population is therefore 25 to 35 years old and are now beyond the original design lifetime and appear to be operating satisfactorily. However are they satisfactory or are a significant number near to failure? Transformers do not have an infinite life and the older and harder worked units are more prone to failure either from external sources, lightning or short-circuit, or internal, insulation, bushing or tapchanger failure. The effects of failures are now critical in a modern power network with the loss of availability, giving safety and financial implications, and cost of financing repairs having a serious effect on operational performance. The problem can be addressed by either refurbishment of older transformers to extend their life or by selective replacement. In order to assist in successfully managing the life of these valuable assets ABB has developed a number of tools to help utilities make informed decisions. These tools extend from “health” assessments of the transformer internal parts, life assessments of external components to the ranking of a population of transformers with respect to end-of-life