Diagnostics of Winding Deformation in a Single-Phase Power Transformer with an Unloaded Tertiary Winding in Operational Mode

The presented paper is focused on the development of an algorithm and software implementation of this algorithm into diagnostics of winding deformation in a single-phase power transformer with an unloaded tertiary winding in operational mode. To implement the algorithm, it is necessary to measure instantaneous values of input voltage and current, output voltage and current, and voltage across the unloaded tertiary winding by means of the electric power quality analyzer PQA – 824. This tool is utilized for signal filtering. The inductances of T-shaped equivalent circuit of the transformer were calculated. Relative deviations of the obtained inductance values were determined on the basis of transformer in operation; these deviations were compared with pre-determined set-points. If the inductances deviate from the set-points, the transformer must be repaired. Modern mathematical software package Mathcad 14 is designed to implement the algorithm. As a result of laboratory tests, the error of the proposed algorithm does not exceed 2% in comparison with the exact method.