Evaluation of Temperature Distribution of Oil-Immersed Transformer Considering Core Gap Insulation using 3D Thermo-Fluid Analysis during No-Load Operation and Cooler Stoppage

Previously, in temperature distribution analysis inside a transformer, there is an overall analysis that simulates the core and tank. However, insulators are not taken into consideration because the analysis cost increases. Therefore, the actual oil flow differs from the analysis results, and there is a possibility that the temperature may be evaluated higher than the actual oil flow, or the location of the hot spot may differ. In this study, we first focused on the temperature change around the core and took into the insulator that greatly contributes to the oil flow. Next, the insulation in the gap between the cores is represented by thermal resistance. This has made it possible to analyze changes in oil flow and temperature distribution inside a transformer, taking insulators into account.