Determining the Residual Magnetic Flux Value of a Single-Phase Transformer Using a Minor Hysteresis Loop

Residual magnetic flux can cause significant problems in electric power system operation if not taken into consideration. The laboratory setup and experimental procedure for determining the residual magnetic flux value of a single-phase transformer using a minor hysteresis loop are presented in this paper. Using the proposed method, residual magnetic flux could be determined without prior knowledge about the last de-energization of the transformer. Only voltage and current measurements are needed, and any physical intervention in the core or in some other parts of the transformer is unnecessary. Also, a significantly lower voltage than the transformer's nominal is used to determine the residual magnetic flux value in the proposed method. The pros and cons of the proposed method, as well as plans for future research are given.