Design and Test of a Prototype 20 kA HTS DC Power Transmission Cable

We present an innovative design for a high temperature superconductor (HTS) dc power transmission system containing an HTS cable connected to optimized multistage current leads and cooled by a multistage turbo-Brayton cryocooler. Analytical results indicate that our proposed 5 MW transmission system can provide a 35% reduction in transmission losses and 93% reduction in system weight, compared with ambient-temperature copper bus. We describe a test stand to assess the performance of the proposed design and discus modifications to the facility to permit cable testing at up to 20 kA current. Efforts to demonstrate full current operation in the simulated system were hampered by higher than expected electrical resistance at the cable joints.