INTER-STRAND COUPLING LOSSES IN SUPERCONDUCTING POWER-CABLES WITHOUT COAXIAL MAGNETIC SHIELDING

This paper deals with computations of inter-strand coupling losses in superconducting power cables with Room Temperature Dielectric (RTD), i n which no coaxial shielding of magnetic field is provided. In three-p hase circuits, magnetic fields produced by neighbouring phases induce in the third one significant currents through contact resistances betw een strands, owing to their helical winding around the cable axis with a pitch inversion between each layer. Analytic expressions are first derived for a simple cable model, with only two strand layers (single ''bilayer''), with or without taking internal screening effects into a ccount. The validity Limit of these computations is determined. Then a generalization to a real n-layer is proposed and the development show s that a homogenization procedure can be performed on the radial coord inate, in some specific cases.