Detailed procedures for interpreting Dissolved Gas Analysis results are described in this guide. The document details: 1) Overview of gas generation in transformer and DGA process; 2) The purpose and application of DGA; 3) DGA quality verification and DGA limitations; 4) DGA interpretation and norms; 5) Fault type definitions and identification; 6) Case studies and interpretation example. The intent is to provide the operator with useful information concerning the serviceability of the equipment. An extensive bibliography on gas evolution, detection, and interpretation is included.

This guide applies to mineral oil-immersed transformers and addresses: a) The theory of combustible gas generation in a transformer b) The interpretation of gas analysis c) Suggested operating procedures d) Various diagnostic techniques, such as Key Gases, Rogers Ratios, Duval Triangle, and other methods e) Case studies and examples f) Evaluation criteria and guidelines g) A bibliography of related literature

The purpose of this document is to provide a guide for evaluating dissolved gases analysis results from mineral oil-immersed transformers using statistical based analytical tools and fault interpretation methods.