Dissolved gas analysis (DGA) is an examination of electrical transformer oil contaminants.[1] Insulating materials within electrical equipment liberate gases as they slowly break down over time. The composition and distribution of these dissolved gases are indicators of the effects of deterioration, such as pyrolysis or partial discharge, and the rate of gas generation indicates the severity.[2] DGA is beneficial to a preventive maintenance program.
The collection and analysis of gases in an oil-insulated transformer was discussed as early as 1928.[3] As of 2018[update], many years of empirical and theoretical study have gone into the analysis of transformer fault gases.
DGA usually consists of sampling the oil and sending the sample to a laboratory for analysis. Mobile DGA units can be transported and used on site as well; some units can be directly connected to a transformer. Online monitoring of electrical equipment is an integral part of the smart grid.