Dual Core Power Transformers: Frequency Response Analysis

Abstract

The Frequency Response Analysis (FRA), is an excellent tool for the diagnosis and detection of internal faults in a transformer, such as: a displacement and winding deformation due to electromagnetic forces as a result of fault currents, the loosening of winding supports as a consequence of electric shocks or when the transformer is transported. These type of faults are mainly involved with the change in the geometry of the transfomer as a whole, a factor that alters the RLC parameters which represent the transformer, and therefore, its resonance points. The standard behavior of the three-phase three limbs transformer can be found in the literature. In this work, an analysis of the tests, which were applied in a double core transformer that is commoly used in arc furnaces, was carried out. The main feature of these transformers is that they feed high currents over a wide range of voltages.