Transformer Voltages, Part I: Analysis of Voltages Listed in ANSI C57, C84, and C92 Standards

The voltages listed in the American National Standards Institute (ANSI) C57 transformer standards are analyzed, tabular comparisons with those listed in the ANSI C84 and C92 preferred voltage standards are provided, and classifications for them as ``preferred,´´ ``non-preferred,´´ or ``non-standard´´ are recommended. Observations are included pertinent to the pattern of the tabulations which are intended to contribute to improved standardization and coordination of ANSI Committees C57, C84, and C92. Information on International Electrotechnical Committee (IEC) voltages is included in the Appendix for comparison. Finally, questions are raised in conclusion to stimulate constructive thought, and hopefully action, in the U.S. electrical industry to improve voltage standardization.