Improvement in maintenance and inspection of transformers in Japan

The economic structural reforms of the early 1990s, exemplified by deregulation, opened the electric power market and encouraged competition, thereby increasing demand for lower transforming facility costs. As a result, research to date on increasing the efficiency of transforming facilities maintenance were synthesized, and new methods for inspecting the facilities were proposed and implemented by taking advantage of maintenance and operational data obtained via equipment diagnostics technologies. This paper describes aging analysis technologies and assessment standards based on the results of analysis of deployed facilities and accident status, as well as economic evaluation methodology from the standpoint of lowering electric power facility costs, and examples of power transformer renewal (e.g. complete removal and rewinding of the coil) in order to demonstrate the status of equipment life extension.