Comparative analysis of three-phase and single-phase dynamic resistance measurement results

Dynamic resistance measurement (DRM) has been proven to be a very effective method in detecting possible faults in on-load tap changers (OLTC). This article gives an overview of the correlation between the three-phase DRM results and the single-phase DRM results. The measurement of OLTC synchronization is also explained. In addition, the demagnetization, which is necessary after any DC test on a transformer, is also described in the second part of this paper.