Comparison of alternating-current losses in two-layer superconducting cables constructed by shell-type and solid-core cylindrical wires

Abstract

Alternating-current losses in two-layer power transmission cables of type-II superconducting wires with cylindrical geometry are numerically investigated with regard to wire cross section. Losses in shell-type and solid-core superconducting wires are calculated through the Finite Element Method for an applied alternating current with 50 Hz frequency. Each cable layer is composed of 20 wires which have 1.0 mm radii, while the thickness of shell-type wires is 0.1 mm. The two wire layers are wound over a copper core such that the inner and outer layer radii are 20.0 and 25.0 mm, respectively. Alternating-current losses at small applied current amplitudes in shell-type wires are three-times smaller than in solid-core wires, where the discrepancy diminishes for high current amplitudes above 90 % of the critical current. Besides, losses in both configurations are considerably higher in outer-layer wires for current amplitudes less than half the critical current, while they converge at higher amplitudes. The reason for smaller losses in shell-type wires at low applied current amplitudes is associated to the fact that current distribution is more homogeneous, whereas magnetic field lines penetrate into the hollow core of these wires. © Springer International Publishing Switzerland 2014.