scope:

This guide provides technical information related to liquid-immersed power transformers insulated with high-temperature materials.

- Guidelines are provided for applying existing qualified high-temperature materials to insulation systems suitable for high-temperature liquid-immersed power transformers.

- Recommendations are made regarding the loading of high-temperature liquid-immersed power transformers.

- Technical information is provided for insulation-system temperature ratings and test procedures for qualifying new high-temperature materials as they become available.

No specific guidance is provided on insulating fluids other than mineral oil. This subject is to be covered in a future revision of this guide once more field experience is available using fluids other than mineral oil in combination with high-temperature solid materials.

Purpose

This guide is intended as a first step in the direction of standardizing the application of high-temperature insulation systems in transformers using insulation materials such as aramid papers, aramid transformerboards, high-temperature enamels, and hybrid systems that include both high-temperature materials and cellulose materials. It provides technical information for the transformer designer as well as for the transformer user.