Partial discharge inception strength in a full-scale HTS cable based on LN2/polypropylene laminated paper insulation

We have been discussing the partial discharge (PD) inception characteristics of liquid nitrogen (LN₂) / polypropylene (PP) laminated paper composite insulation system for high temperature superconducting (HTS) cables. Based on the volume effect on PD inception electric field strength (PDIE) with a parameter called SSLV (statistical stressed liquid volume), in this paper, we evaluated PDIE of a full-scale HTS cable sample. Experimental results revealed that PDIE of the full-scale HTS cable sample at atmospheric LN₂ pressure under AC voltage application was consistent with the minimum PDIE value in the previous experiments. These results verify that 17.4 kV_rms/mm obtained in this paper can be regarded as a criterion of PDIE in consideration of the volume effect for the practical insulation design of actual HTS cables.