SFRA Characteristics of Power Transformer Internal Winding Considering the Resonant Effect

Transformer is the main equipment in the electricity network which plays an important role because the failure of the transformer can cause seriously power outages. One of the failures of the transformer is breakdown insulation caused by over voltages. Failure of the transformer due to over voltage even still occurs on transformers that are in good condition and also protected by arresters. In this condition, one of the factors suspected as the cause of failure is the phenomenon of resonance over voltages. Several studies have been conducted to investigate the phenomenon of resonance in the transformer, both the phenomenon of ferro resonance and internal winding resonance. Previous research conducted was generally related to methods to reduce impacts, both by installing protective equipment and choosing the right design. This research was conducted for evaluating the resonance characteristic inside power transformer winding. Based on the results of the study of high frequency characteristics using Sweep Frequency Response Analysis (SFRA) on power transformer with layer type winding, it was found that the highly potential occurrence for internal winding resonance that needs to be considered is the resonance that occur at the internal high voltage winding. While the internal resonance winding at low voltage winding and inter-winding resonance is not significant.