Abstract:The assessment of the overload capacity of oil-immersed power transformers is vital for ensuring their safe and reliable operation, as well as maintaining the stability of the entire power system. Despite the absence of a simple and effective method for this assessment, this study introduces an engineering evaluation approach based on average oil temperature rise and top oil temperature. By analyzing key factors that affect the overload capacity of oil-immersed power transformers, and integrating transformer design principles with the concept of equivalent heat dissipation area of plate-type radiator tanks, the proposed method accounts for the thermal characteristics of the transformer, cooling system performance, load current, and ambient temperature''s impact on temperature rise. This simplified calculation process enhances the accuracy of the assessment results. The method''s validity was confirmed through comparison with actual operational data from in-service power transformers, demonstrating its capability to accurately assess overload capacity.