Electrical Insulation Characteristics and Mechanisms of Low Dielectric Loss Materials for High-Voltage HTS Cables

Toward the practical development of high-voltage high-temperature superconducting (HTS) cables, high electrical insulation characteristics, and low dielectric loss become important. Dielectric loss drastically increases with the increase of operation voltage of HTS cables. Therefore, it is highly expected to find a novel insulating material with low dielectric loss for the high-voltage HTS cables. We have focused on Tyvek (R), polyethylene (PE) nonwoven fabric, and Tyvek (R)/PE, a syntactic paper bonding PE-sheet on Tyvek (R) by heat, as low dielectric loss materials. In this paper, we investigated fundamental partial discharge inception characteristics and their mechanisms of Tyvek (R) immersed in liquid nitrogen (LN2). In addition, we compared the electrical insulation characteristics of Tyvek (R), Tyvek (R)/PE, and polypropylene laminated paper (PPLP (R)), and discussed their mechanisms.