Turbogenerator electromagnetic design-the design of eddy current shields for screening of end-regions

The author discusses the design of eddy current shields for turbogenerators. Using the finite element method the influence of shield thickness upon both the effectiveness of screening and the losses in the shield itself have been investigated. Results indicate that appreciable screening still takes place even when the shield is reduced to a thickness considerably less than one skin depth, but that such a thin shield will incur high eddy current losses. Work on wrap-around shields shows them to be effective in screening the inner radius of the stator core end plate. They also reduce stator core back axial flux, but this is accompanied by a modest increase in stator tooth axial fluxes. Losses in wrap-around shields are considerably greater than in their flat counterparts