Understanding Dissolved Gas Analysis (DGA) Techniques and Interpretations

The use of Dissolved Gas Analysis (DGA) as a method for determining the types of pending or occurring faults within power transformers has been in practice for many years. It has been proven that the generation of certain gases within a transformer is an excellent indicator that a failure is pending. DGA techniques have become so sensitive and accurate at measuring these gases that the entire scheme has become standard practice as part of the normal maintenance for many electric power utility companies. Despite how effective DGA techniques have become, the proper use and interpretation of gas level results (i.e., ppm levels) is still not fully understood by many utility people. Therefore, it is the intent of this paper to provide common knowledge and understanding of all the tools, methods, and techniques available for non-chemical engineers within typical utility companies. We will fully describe each of the available interpretation techniques as well as provide a comparison of the accuracy and reliability of each diagnostic method based on one independent case study.