Relay Protection of Power Transformers

This report of the AIEE relay subcommittee presents the results of a 3-year investigation of present and preferred practices in the relay protection of power transformers. Consideration is given to the influence of advances in the protective art and progress in the design of and methods of operating power transformers. A survey covering experience with over 56 million kva of power transformers has been analyzed in the light of the characteristics of the relay devices now available, in order to develop criterions of adequacy of protection and its inherent limitations and to recommend desirable improvements in devices and methods.