DGA Course – e-lesson #5 – Theories & practice of modern DGA diagnosis, standards, guides, schemes and HI models

This lesson provides an overview of the theory and practice of modern DGA diagnosis for power transformers. It covers the various categories of DGA diagnosis methods, including predictive, graphical, physical/chemical, and combined approaches. The session explores the historical development of DGA diagnosis and discusses the challenges and limitations, such as setting appropriate gas concentration limits. Emphasis is placed on the success probability and reliability of different DGA methods, as well as the role of measurement accuracy and expert interpretation. The thermodynamic principles of gas formation are explained, and key graphical and ratio-based diagnosis techniques are reviewed. Finally, the concept of health index and its importance in DGA-based transformer assessment are discussed.