Design for a superconducting a.c. power cable

The paper describes a design study for a 750 MVA 33 kV superconducting a.c. power cable. Conductor and dielectric design, thermal insulation and refrigeration and methods of construction and installation are all considered. Niobium is the chosen conductor material, and a triple coaxial construction the chosen conductor geometry. The capital costs of the systems considered are estimated to be rather more than twice that of the equivalent 275kV conventional oil-filled cables. The running costs are about the same as that of the conventional equivalent, but represent only a small proportion of the total cost. Problems which need further study and development work, and whose solution could lead to significant design improvements and cost reductions, are: (a) protection of the conductors against current overload, (b) thermal contraction and (c) dielectric design. It is concluded that, though superconducting cables are unlikely to be economical at the power level considered in the study, they may find application in the multi-GVA region.