Assessment of Solid Insulationof Power Transformers through Dissolved Gas Analysis

Power Transformers are the most vital equipment in a sub-station / Receiving station. Failure of a transformer leads to loss of revenue besides affecting reliability of power supply to consumers and also on cost. Hence assessment of transformers plays crucial role in the overall integrity of power system which includes remaining life of the equipment. In order to ensure that Power Transformers provide long and trouble-free service, several diagnostic tests are carried out and remedial actions initiated throughout their operational lifetime. It can be done by assessing the extent of degradation of the cellulosic paper & oil insulation through furan content in oil, degree of polymerization of paper insulation and dissolved gas analysis (DGA) in oil. This can help the utilities in making optimum use of the Transformers and also taking timely decisions regarding refurbishment / replacement of Transformers. Therefore, attempts are being made to discuss the details of furan analysis, degree of polymerization and DGA with few case studies in assessment of power transformers.