Using the FDS Technique in Transformer Factory Drying

This paper presents an approach for the feasible use of frequency-domain spectroscopy technique, to evaluate transformer factory drying and by this, to determine the most suitable moment to finish the drying process. To enable the use of FDS in transformer factory drying, the reference dielectric response curves of the air-paper insulation system of the transformers under drying, are necessary. Those reference curves were obtained in two ways: First scale models were used to emulate the insulation system between windings, the second way consisted in the simulation of the inter windings insulate through a finite element model. The feasibility of frequency-domain spectroscopy technique in transformer factory drying, as well as the methods to obtain the dielectric response reference curves, were validated through several experiments, and by the drying of five transformers, all carried out in the facilities of Transformadores de Colombia.