Computations of losses and temperatures in the core ends of high voltage turbo-generator

The work described in this paper is Io investigate the additional losses and consequent temperature in core ends in a turbo-generator wound with cables. Electromagnetic calculations are made with 3D FE models, which include the lamination material with anisotropic properties both in magnetic permeability and electric conductivity. The models also include the geometry of the stator teeth and eventually the axial steps designated to reduce the core end losses. The 3D model of the rotor consists of field windings with straight in-slot parts and curved end parts. The thermal models are simplified into two dimensions and include the heat sources dumped from the 3D electromagnetic solutions. The influences of power factor on additional iron losses are studied for this cable wound machine and conventional machines. The calculation results show that the additional iron losses can be reduced to about 15% by introducing some small steps around the airgap corner of core ends