Analyzing the Impact of Cover Design on Stray Losses in High Current Distribution Transformers Based on 3D-FEM Analysis

A high current distribution transformer (HCDT) is a type of transformer that is typically used in industrial and commercial applications where the electricity demand is greater and would be inadequate due to the higher power requirements of the electrical loads being served, requiring transformers capable of handling higher current levels. HCDTs are designed with larger conductors and cooling systems to accommodate the increased current flow without overheating. Stray loss which is 20-25% of the total load loss of the transformer, can have a significant impact on thermal performance. When the current levels are high, the stray losses also increase due to the higher magnetic flux density and increased eddy current losses on the cover of HCDTs. This can lead to elevated temperatures within the transformer, potentially causing overheating, which can affect the insulation materials, reduce the transformer’s efficiency, and lead to premature aging and failure of the transformer. Their failure can affect reliability, safety, and system capacity, and result in significant costs for the utility company, potentially leading to widespread outages if not addressed promptly. To mitigate the impact of stray losses on thermal performance, the cover of high current distribution transformers is designed with non-magnetic segments which are considered to minimize energy losses and maximize the transformer’s overall efficiency. In this research, the three-dimensional finite element method has been used to accurately analyze the impact of cover design on the stray losses of a 4 MVA HCDT.