From Frequency Domain to Temperature Domain of Transformer Liquid Insulation

Abstract

The dielectric response of the overall transformer insulation is an invaluable source of information for those involved in the manufacture, operation and maintenance of power and distribution transformers. One of the greatest advances in the use of the transformer insulation dielectric response is without a doubt the possibility of performing advanced diagnostics of the oil-paper insulation to determine the moisture concentration of the solid insulation and the quality of the liquid insulation. Moreover, based on the knowledge acquired, the dielectric response in the frequency domain allows correct definition of the thermal behavior of dielectric parameters such as power factor or dissipation factor. Dissipation factor or power factor are dependent on frequency and temperature. It is clear for field users that the thermal behavior of the dielectric parameters is related to the condition of the overall insulation system and not just to the construction or nameplate of the transformer. Therefore, the application of the dielectric response in the frequency domain is a more accurate method to determine the real thermal behavior of the power factor. In the context of this document, authors investigate different liquid insulation materials with different aging/quality conditions, their dielectric response in the frequency domain and the conversion of this response into the temperature domain.