Design optimization of power transformers. Part 2. Eddy current analyses for tank wall and core clamping parts

For pt.1 see ibid., p.1365-1370, (2004). To maintain quality, performance and competiveness, finite element analyses are increasingly utilized for the initial design, the design review and the design optimization of power transformers. The detailed geometry of windings, core, tank wall as well as insulation and clamping parts requires 3D numerical calculation methods in order to obtain high accurate values for the material utilization. The paper presents 3D finite element analyses for the distribution of eddy currents in the core clamping parts and the tank wall of power transformers. Since these eddy current losses are obviously different between measurements of load losses and normal operational conditions, the calculation shows the regions of possible hot-spot temperatures with normal operational conditions.