IEEE C57.115-1991

This guide covers general recommendations for loading mineral-oil immersed power transformers manufactured in accordance with IEEE C57.12.00-1987 Ill' and having a maximum nameplate rating in excess of 100 phase). Such transformers have an average winding rise of 65 "C maximum and a hottest spot rise of 80 "C maximum at rated load.



Revision Standard - Inactive-Withdrawn. The guide covers modern power transformers rated above 100 MVA, three-phase equivalent and 65°C rise. The general approach is tutorial. Four different types of loading, that is, normal life expectancy loading, planned loading beyond nameplate rating, long-time emergency loading, and short-time emergency loading, are considered. The various effects of loading a transformer in excess of its nameplate rating are discussed. Temperature and maximum loading limitations are suggested.