Electrical insulation property of liquid nitrogen/synthetic paper composite electrical insulation layer for high temperature superconducting cable

Author(s):  
H. Suzuki ◽  
T. Takahashi ◽  
T. Okamoto ◽  
S. Akita ◽  
K. Yasuda
2011 ◽  
Vol 71-78 ◽  
pp. 4389-4393 ◽  
Author(s):  
Yao Ping Zhang ◽  
Jian Yue Yu ◽  
Yong Zhao ◽  
Ben Lin Liu

Based on some special merits such as self-stability, energy-consuming-efficiency, less pollution, high reliability, and so on, high temperature superconducting maglev (HTSM) is one of the promising potential technologies among present Maglev technologies for the future evacuated tube transportation (ETT). In this paper, the possibility, the merits, and the demerits of the applications of HTSM in ETT system are investigated. Especially, two application issues, liquid nitrogen vessel on the vehicle and isolated gate set in ETT, are discussed and solutions are suggested. On the first issue, this paper suggests to install a pressure relief valve on the sealed liquid nitrogen vessel so as to reduce the liquid nitrogen vaporization in the vacuum tube. As for the second issue, this paper recommends to use HTSM permanent magnet (PM) track structure with a streamline separated gap between the surface of track and the bottom of liquid nitrogen vessel. Those guideway structure could fit to the isolation gate setting in ETT.


2006 ◽  
Vol 47 ◽  
pp. 204-211
Author(s):  
Hiroyuki Fujimoto ◽  
Hiroshi Hata ◽  
Hiroki Kamijo ◽  
Ken Nagashima ◽  
Kazuya Ikeda ◽  
...  

Having undertaken studies into a lightweight and highly efficient superconducting transformer for rolling stock, we developed a prototype with a primary winding, four secondary windings and a tertiary winding using Bi-2223 high temperature superconducting wire. Its primary voltage is 25kV, which is widely adopted as the catenary voltage on the world's high-speed lines. We adopted liquid nitrogen cooling, the weight being 1.71t excluding the refrigerator. The maximum output available to maintain superconductivity is 3.5MVA. We also introduce railways in Japan.


Author(s):  
V.S. Zarubin ◽  
G.N. Kuvyrkin ◽  
I.Yu. Savelyeva

For the reliable operation of a high-voltage DC cable with high-temperature superconducting current-carrying conductors with a sufficiently high difference in electrical potentials, it is necessary to maintain a fixed temperature state not only of the conductors but also of other cable elements, including the electrical insulation layer. In this layer, despite the high electrical resistivity of its material, which can be polymer dielectrics, Joule heat is released. The purpose of this study was to build a mathematical model that describes the temperature state of an electrical insulation layer made in the form of a long hollow circular cylinder, on the surfaces of which a constant potential difference of the electric field is set. Within the study, we consider an alternative design of a cable with central and external annular channels for cooling liquid nitrogen. Using a mathematical model, we obtained integral relations that connect the parameters of the temperature state of this layer, the conditions of heat transfer on its surfaces, and the temperature-dependent coefficient of thermal conductivity and electrical resistivity of an electrical insulating material with a given difference in electrical potentials. A quantitative analysis of integral relations is carried out as applied to the layer of electrical insulation of the superconducting cable. The results of the analysis make it possible to assess the possibilities of using specific electrical insulating materials in cooled high-voltage DC cables under design, including superconducting cables cooled with liquid nitrogen


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