Development of measuring techniques used in evaluating the insulation condition of large power transformers

This report illustrates the experience gained at ENEL over a 15 year period of dielectric diagnostic testing. The considerable amount of information obtained over the years from the large number of large transformers has contributed to the development of measuring techniques aimed at monitoring and inspection machines in service. ENEL performs those tests which best highlight the failure mechanisms, namely: dissolved gas in oil analysis, furfural analysis, and partial discharges measurement