Insulation systems for superconducting transmission cables

This paper describes shortly the status of superconducting transmission lines and assesses what impact the recently discovered BSCCO superconductors may have on the design of the cables.Two basically different insulation systems are discussed:1) The room temperature dielectric design, where the electrical insulation is placed outside both the superconducting tube and the cryostat. The superconducting tube is cooled by liquid nitrogen which is pumped through the hollow part of the tube.2) The cryogenic dielectric design, where the electrical insulation is placed inside the cryostat and thus is kept at temperature near 77 K.The optimal design is determined by a loss evaluation in relation to the power transfer capacity of the cable. Development work in progress on the design and construction of superconducting cables in Denmark is described as an example.