The recommendations presented in this guide apply to the shipping, handling, inspection, installation, and maintenance of liquid-immersed power transformers rated 501 kVA and above with secondary voltages of 1000 V and above. This guide covers the entire range of power transformers, including extra high-voltage (EHV) transformers. This guide does not cover special transformers such as furnace transformers, rectifier transformers, etc. Distinctions are made as required for various MVA ratings, voltage ratings, and types of liquid insulation. Clause 3 contains information for use with transformers rated below 10 MVA with high voltages less than 69 kV. Clause 4 applies to transformers rated 10 MVA and above with primary voltages of 69 kV and above, including EHV transformers. NOTE 1: For transformers with primary voltages that are less than 69 kV and larger than 10 MVA, users should follow Clause 4.1 NOTE 2: The user should carefully read the instruction book supplied by the manufacturer. Any conflict with this guide that may occur should be resolved with the manufacturer for each specific installation. This Guide intents to provide the users the procedures, criteria and current practices in the installation and maintenance of liquid immersed power transformers. Revision Standard - Superseded. This guide provides guidance and recommended practices on the installation and maintenance of liquid-immersed power transformers rated 501 kVA and above with secondary voltages of 1000 V and above. This guide covers the entire range of power transformers, including extra high voltage (EHV) transformers. This guide does not cover special transformers such as furnace transformers, rectifier transformers etc. Distinctions are made as required for various MVA ratings, voltage ratings, and types of liquid insulation.