Frequency Response of Transformer Winding: A Case Study based on a Laboratory Model

Many researchers have been studying frequency response analysis measurements and its relevant interpretations. Nowadays, the measurements have been well standardized. However, more objective results interpretation is still needed. This research used a laboratory winding model to enable the simulation of mechanical defects and obtained controlled measurements of its frequency response. The vectfit and the Chinese standard methods were used to compare different interpretations. Results indicated an agreement between the vectfit method and the experimental data, demonstrating that the model has potential of providing a powerful tool to interpretation of power transformer frequency behaviour. Nonetheless, the Chinese standard failed to show the severity of the defects, indicating a normal winding for some cases evaluated. For an overall maintenance strategy, frequency response tests can help taking restorative measures before deterioration reaches a point where failure of the transformer is inevitable.