The 35 m superconducting cable test facility

To demonstrate the technical feasibility and capability of superconducting ac cables a 35 m long ac single phase test cable for 110 kV and 10 kA is under construction at present. The rigid cryogenic envelope has already been assembled. Good experience was gained with the applied mounting technique which is described. Wires consisting of a high purity Al-core enclosed by a thin layer of Nb are used as cable conductors. They were fabricated in lengths of several thousand meters under large scale conditions and exhibited excellent electrical behaviour. After manufacturing some dummies with pure Al-wires, a 50 m long originally sized flexible cable core consisting of superconducting wires and wrapped HDPE tape insulation was fabricated on conventional cable machinery in our cable works. Dielectric measurements at 4.2 K and 2.5 bar on originally sized and large scale fabricated cable core pieces yielded breakdown voltages, partial discharge inception voltages and dissipation factors which are compatible with cable standards. Two one phase 110 kV - 10 kA cable terminations have been constructed and tested. They showed satisfying behaviour with respect to stress and current loads.