Transient analysis of the shielding system in a superconducting generator

The electromagnetic behavior, under transient conditions, of the rotor shielding systems of superconducting turbogenerators as the physical and geometrical parameters of the screen vary, is analyzed in this paper. Transient phenomena in the stator or excitation field and those caused by a single phase stator fault are considered; with reference to these cases, the expressions for the radial and tangential components of the magnetic field are given for the hypothesis of bidimensional analysis. Finally, starting from the rough dimensions of a two-pole three-phase alternator of about 1300 MVA and with reference, respectively, to a step excitation functions and to a negative sequence stator field, a set of graphs has been prepared. These bring out the influence of some significant parameters, such as the type of material, the operating temperature, and the thickness and number of the screen elements, on the electromagnetic attenuation properties of the shield.