The Gassing of Insulating Fluids

Since the end of the 1950s, the extraction of dissolved gases from an oil sample and the determination of the nature and concentration of these gases have been serving as a means of faults detection. The type and extent of a defect can often be diagnosed from the composition of the gases and the rate at which they are produced. This technique, known as Dissolved Gas Analysis (DGA) for detecting certain categories of faults in oil-filled devices that cannot be readily detected by other conventional methods, remains one of the most widely used today. Although there is general consensus that increasing the concentration of dissolved gas is a precursor of local deterioration of insulation, opinions differ when it comes to interpretation of the symptoms. Consequently, the first step towards improving the accuracy of DGA techniques should be understanding the mechanisms associated with chemical reactions contributing to the generation of fault gases in transformer oils. This article intends to show how the chemical composition of the insulation system may affect the analyses. Some data was also included for further understanding