2D finite-element determination of tank wall losses in pad-mounted transformers

This paper presents a two-dimensional (2D) finite-element (FE) analysis of losses generated in the tank wall surrounding the high-current bushings of pad-mounted transformers. Although the problem is truly three-dimensional (3D), it is shown that a 2D approach gives results that closely agree with 3D simulations and experimental results. Thus, it is possible to avoid the very demanding computational resources required for 3D modeling or the cost of experiments. Nine cases are analyzed to study the impact of inserting small plates of different geometry (located near the high-current terminals) on the reduction of tank losses. Significant reductions in stray losses on the tank wall are obtained with low-cost plate inserts. 2D and 3D time-harmonic FE models are used to determine the losses in the tank wall. Two load loss tests were carried out on experimental transformers to validate the simulations.