Practical AC loss and thermal considerations for HTS power transmission cable systems

The use of high-temperature superconducting materials for power-transmissio n cable applications is being realized in prototype situations. It is well known that ac loss decreases as the temperature of the conductor decreases. Also, thermal losses are higher at lower temperatures, owing to the increa sed temperature difference between ambient and cryogenic operating conditio ns. Both counterflow and parallel-flow cooling arrangements have been propo sed in the literature and significantly affect temperature distribution alo ng the cable. In this investigation, the counteracting ac loss and thermal losses are analyzed for both cooling configurations to determine the benefi ts and limits of each. The thermal-insulation performance levels of materia ls versus those of typical systems in operation are presented. Widespread a pplication of long length flexible cable systems, from the refrigeration pa int of view, mill depend on an energy-efficient cryogenic system that is ec onomical to manufacture and operate. While the counterflow arrangement will typically have a lower heat load, it has a length ii mit arising from the large pressure drop associated with the configuration.