A procedure to be used to perform a failure analysis is recommended. The procedure is primarily focused on power transformers used on electric utility systems, although it may be used for an investigation into any ac transformer failure. This document provides a methodology by which the most probable cause of any particular transformer failure may be determined. This document is also intended to encourage the establishment of routine and uniform data collection procedures, consistency of nomenclature and compatibility with similar efforts by other organizations, and cooperative efforts by users and manufacturers during the failure analysis.(Also supersedes IEEE C57.117-1986)

This guide recommends a procedure to be used to perform and document a failure analysis and the reporting and statistical analysis of reliability of power transformers and shunt reactors used on electric power systems.

This document is intended to provide a methodology by which the most probable cause of any particular transformer failure may be determined by applying the scientific method to investigations; provide sufficient guidelines, examples, and case histories to promote uniformity in the analysis of transformer failures; encourage the establishment of routine and uniform data collection so that valuable facts are not lost or destroyed; encourage consistency of nomenclature and compatibility with similar efforts by other organizations (Examples include but not limited to CIGRE, EEI, IEC, NEMA, NERC, and AEIC); and encourage cooperative efforts by users and manufacturers during the failure analysis.