Frequency characterization of cast-resin transformers

The performance and the reliability of the power transformers are critical parameters for the electric power production, transmission and utilization. In the last years diagnostic techniques have been widely utilized to improve the safety and to reduce the maintenance costs of power transformers. The Bticino group had recently acquired the plant in Castellalto, Italy, from the Zucchini EMM, that is devoted to the design and the production of cast-resin MV/LV power transformers; a research project concerning the application of the SFRA (Sweep Frequency Response Analysis) to Bticino transformers has been started as a cooperation with the Department of Electrical and Information Engineering of the University of L´Aquila, with the main aim of creating a database for the fault analysis. This paper presents the developed measurement system and the first experimental results that have been obtained by applying the SFRA to transformers of different rated power.