This guide covers general recommendations for lading mineral-oil power transformers, manufactured in accordance with ANSI C57.12.10-1976 and ANSI C57.12.30-1977 and other oil-insulated power transformers up to and including 100 MVA maximum nameplate rating. It is based mostly on aging of the winding insulation. Loading of transformers larger that 100 MVA may be limited by factors other than insulation aging such as stray flux, etc. When it is known that such limitations do not exist and insulation aging rather that oil temperature, gassing, tank heating, etc is the controlling factor, this guide may be used. This guide may also be used for askarel filled transformers.