Post-Seismic Fault Detection and Diagnosis on Power Transformer: A Comprehensive Review and Study Case of Cianjur Earthquake

A power transformer is a vital component in an electrical network system because of its key role in the power system. Guaranteeing transformer continuity and operability in all environmental conditions has emerged as a major topic in transformer fault detection and diagnosis, particularly considering large seismic events that have grown widespread all over the world, with notable ones including Cianjur Earthquake in West Java, Indonesia in 2022. Different approaches for transformer diagnostics are discussed in this research. Along with other diagnostic techniques, SFRA is recognized as one of the most appropriate techniques to identify faults or deformations in power transformers. From the results and analysis of the turn ratio test, it can be concluded that there is no short-circuit in the winding, while in the tan delta, DC insulation resistance, and breakdown voltage tests it can be concluded that there are no significant contaminants in the insulation. From the results of the OLTC dynamic resistance test, it can be concluded that there is no open circuit in the windings at each tap, and there are no defects in the diverter switch or in the OLTC mechanical parts in general. On the other hand, the SFRA test results concluded that there were indications of inter-disk faults and dielectric leakage currents on windings, also residual magnetism or slight deformation in the transformer core. However, the degree of deterioration that occurred was relatively mild and still within the permissible standard limits, so that all four transformers at the Cianjur substation were still usable and operating well today, which had been 6 months after the earthquake.