Impact of chemical composition of the oil on their gassing behaviour

Dissolved Gas Analysis (DGA) is a technique allowing detecting certain categories of faults, affecting oil immersed power equipment that cannot be easily detected by other conventional methods. It is one of the most widely used diagnostic and preventive monitoring tools for power transformers today. Although there is consensus that increased dissolved gas concentration represents a harbinger of local insulation deterioration, opinions differ when it comes to interpretation. About twenty methods developed to identify incipient failures have since emerged. Our investigations have shown that the chemical composition of a fluid (parent molecule and decay products) affects the gassing tendency. Consequently, this may affect the DGA interpretation results.