Partial discharge inception V-t characteristics for pressurized liquid nitrogen/PPLP/sup /spl reg// composite insulation system

We discuss partial discharge (PD) inception characteristics and V-t characteristics of PD inception in liquid nitrogen (LN/sub 2/)/polypropylene laminated paper (PPLP/sup /spl reg//) composite insulation system for high temperature superconducting (HTS) cable. Experimental results revealed that the magnitude of initial PD was in the range of 2.0-30 pC irrespective of butt gap condition and the initial PD was generated at the first and third quadrant of the voltage phase independent pressurized condition of LN/sub 2/. Furthermore, life time indices n of V-t characteristics at PD inception were experimentally identified and the dependency on the pressure of LN/sub 2/ was clarified.