The contribution of dissolved gas analysis as a diagnostic tool for the evaluation of the corrosive sulphur activity in oil insulated traction transformers

This work presents a study of Dissolved Gas Analysis in samples of mineral insulating oil, corrosive or suspicious corrosive according to the test ASTM D1275B. The results showed that the change of the properties of the attacked surfaces causes a malfunction in the transformer. It seems from the results that the DGA should be consider as important diagnostic tool for the presents of corrosive factors in transformers oil. The DGA method can be an additional diagnostic "tool" for confirmation and monitoring of the evolution of the phenomenon, especially when control is systematic and starts before transformer\´s electrification and operation. This proposal is enhanced by the fact that the required equipment for DGA is a common one for chemical analysis labs.