@article{oai:nagoya.repo.nii.ac.jp:00005179, author = {Okubo, H. and Hazeyama, M. and Hayakawa, N. and Honjo, S. and Masuda, T.}, issue = {6}, journal = {IEEE Transactions on Dielectrics and Electrical Insulation [see also IEEE Transactions on Electrical Insulation]}, month = {Dec}, note = {In this paper, we studied partial discharge (PD) inception characteristics and V-t characteristics of PD inception in liquid nitrogen (LN,)/polypropylene laminated paper (PPLP" 1 composite insulation system for high temperature superconducting (.ITS) 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 voltage phase. PD inception electric field strength (PDIE) without butt gap was 5-10% higher than that with butt gap and thicker butt gap gave larger PDIE drop. Moreover, PDIE with butt gap depended on the butt gap thickness and the number of PPLP" layers. The reason is explained by the existing probability of weak points of electrical insulation at butt gap. Finally, lifetime indices n of V-t characteristics at PD inception were obtained as 80-100 irrespective of butt gap condition. These values showed enough flat characteristics of V-t phenomena of electrical insulation.}, pages = {945--951}, title = {V-t characteristics of partial discharge inception in liquid nitrogen/ PPLP/sup /spl reg// composite insulation system for HTS cable}, volume = {9}, year = {2002} }