Investigating the short-circuit endurance of 220 kV transformer in a 400 kV grid system

Abstract In transmission and distribution networks, transformers are subjected to numerous system faults over their operational life span, so testing of transformers is crucial. To ensure a robust design and optimal performance, comprehensive testing is required as per the international standard. The IEC60076-5 Standard specifies that a transformer’s short-circuit (SC) withstand capability can be validated through calculation, design analysis, or testing in accredited laboratories. This study takes an experimental approach to assess the short-circuit withstand capability of a 160 MVA, 230/110 kV, 3-phase transformer using a 400 kV grid supply as per the IEC standard. The focus is on the general requirements for testing the 230 kV transformer, and the equipment used to identify the most effective method for conducting dynamic short-circuit (DSC) tests under real grid conditions with the available 400 kV grid source. Additionally, the study verifies the test results, assessing the transformer’s ability to withstand short-circuit events. Results show that the high-capacity autotransformer successfully endured high-voltage to medium-voltage (HV-MV) short-circuit conditions, demonstrating its resilience against short circuits under various dynamic scenarios.