A comparison of IEC 76 and ANSI C57.12 on transformers

There is a growing need to look out into new markets outside of the USA, which requires a proper understanding of international standards. In the field of transformers, which are vital links in power delivery, the major international standard is IEC 76. In this paper, a brief comparison of major parameters like service conditions, categories, impedance, temperature rises, tolerance, dielectric insulation levels, test requirements, etc. of transformers in IEC 76 and IEEE/ANSI C57, have been brought out. An attempt is made in this paper to have a quick understanding of important technical parameters of transformers per IEC 76, in comparison with IEEE/ANSI C 57. Clause numbers in both specifications are mentioned against the parameters for easy reference for the readers. Because of the volume of the standards and details included in individual sections, it is difficult to cover a detailed comparison in a technical paper. Only major parameters which are commonly encountered in inquiry, order, manufacturing and of testing of power transformers are covered in this paper. In order to bring out direct comparison, the rest of the entire paper is presented in tabular form. Wherever necessary, separate details have been provided for dry-type and oil-filled transformers.