Development of an electromagnetic shield against proximity heating around the terminal leads of a large hydrogenerator

Due to space restrictions in the power house of a 612 MVA hydrogenerator, the terminal leads are routed through a magnetic steel structure. Without adequate shielding, the proximity heating in this support structure is expected to result in temperatures up to 500/spl deg/C. This paper describes laboratory tests as well as time-harmonic finite element analyses that were carried out in the development of a novel shielding configuration of the steel structure. With this new shield, the temperature rise is reduced to 45/spl deg/C which is confirmed by preliminary site tests.