Mechanical Bending Characteristics of HTS DC Cable

High-temperature superconducting (HTS) dc cable is expected to be an application as larger transmission of electrical power because of, ultimately, lower loss, as well as large capacity compared with ac cable. In order to secure long life, reliability, and compactness of HTS DC cable, the roles of breakdown properties and insulation design are important. In actual cable, breakdown properties are influenced by not only up-scale effect but also mechanical stress during cable production and installation. For HTS cable, polypropylene laminated paper has been used as insulation material. Polypropylene laminated paper has been widely adopted as insulating material for HTS cable. In this paper, the model cables with different thicknesses were fabricated, and the breakdown tests were performed. Based on the results, an improved insulation design of 250-kV-class HTS dc cable was proposed with volume effect. The breakdown characteristics of bended cables were also investigated with various testing conditions.