Partial discharge inception characteristics of LN/sub 2//polypropylene laminated paper composite insulation system for high temperature superconducting cables |
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Authors: | Hayakawa N Kobayashi T Hazeyama M Takahashi T Yasuda K Okubo H |
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Affiliation: | Dept. of Electr. Eng. & Comput. Sci., Nagoya Univ.; |
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Abstract: | Partial discharge (PD) inception characteristics of liquid nitrogen (LN2)/polypropylene (PP) laminated paper composite insulation system for high temperature superconducting (HTS) cables were investigated in terms of the volume effect and the V-t characteristics. The electrical and optical measurements of PD inception characteristics showed that initial PD could be generated between PP laminated paper layers, as well as in a butt gap. Using a parameter called statistically stressed liquid volume (SSLV) based on the discharge probability in both butt gaps and LN2-filled thin layers between PP laminated papers, we could systematically analyze and evaluate the volume effect on PD inception stress (PDIE). Furthermore, experimental results revealed that n values of V-t characteristics at PD inception were as high as 80-110. On the other hand, the lower n values obtained at breakdown were interpreted by the intensified PD development in thermal bubbles generated after the PD inception |
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