Localized Winding Loss Mitigation in Distribution Transformers Based on Directional Leakage Flux and Conductor Geometry

The rapid expansion of artificial intelligence and data centers increases electricity demand and the need for reliable distribution transformers. Total winding loss alone does not characterize the magnitude or location of localized loss concentration. This study examines mitigation of localized electromagnetic loss concentration through conductor reshaping while assessing total winding loss and electric field stress. A 500 kVA, three-phase, oil-immersed distribution transformer was analyzed using two-dimensional transient electromagnetic and electrostatic finite-element models. Conductor aspect ratios and relative winding heights were varied for the low-voltage (LV) and high-voltage (HV) windings while preserving each conductor’s cross-sectional area. The modified geometry reduced peak loss densities in the LV and HV windings by approximately 46.8% and 13.0%, respectively. Increasing winding height mismatch redistributed directional leakage flux, shifted the LV peak-loss-density location, and increased localized loss when the mismatch became excessive. In the final geometry, total winding loss decreased by approximately 0.73%, whereas the maximum electric field increased by approximately 0.53%. The results demonstrate that coordinated adjustment of conductor geometry and relative winding height can mitigate localized electromagnetic loss concentration while maintaining total loss and calculated electric field stress at levels comparable to the reference design under the investigated conditions.