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Highlights: [•] The critical current is measured for a three-layer BSCCO stacked conductor. [•] The critical current strongly depends on the current feeding mode. [•] Opposite-direction feeding mode leads to 50% increase of the critical current. [•] Current feeding mode effect implies onto a manufacture of a flexible DC power cable. [ABSTRACT FROM AUTHOR]

Abstract: Efficiency of the energy management can be significantly enhanced using the technology of superconducting (SC) power transmission. A high cost of the existing experimental SC lines is determined to a great extent by the use of expensive cryopumps. Moreover, pumping stations require maintenance, and cryopumps are a source of additional heat load for the system. It was proposed to utilize a thermal siphon effect to naturally circulate liquid nitrogen (LN2) through the cryopipes. Calculations showed the feasibility of this idea. Currently, there is an opportunity to verify of our estimations using new 200m experimental facility at Chubu University. The level difference of circulation loop is almost 5m, therefore noticeable driving force due to the difference in densities of “cold” LN2 near the inlet and “warm” LN2 near the outlet adds to the pump power. The cryopipe is equipped with heaters, allowing to carefully change the intensity and distribution of heat load to make it possible to analyze in details the influence of thermosiphon effect on the circulation of LN2 and pump energy saving. [Copyright &y& Elsevier]

Abstract: We designed and constructed the experimental device of 200-meter superconducting DC cable system in the beginning of 2010 and did the first experiment until March, 2010, and the second experiment has been done from August to October 2010. This experimental device is called CASER-2, and the main aim of the experiment is to demonstrate high performance of DC superconducting cable system for comparing the copper cable system. Thermal contraction and expansion during the thermal cycle are discussed in the paper because if the thermal stress of the HTS tape conductor is high, the critical current of the HTS tape is reduced. Therefore, it is the first priority to keep the system in high performance and safety. We also mentioned several experiments and ideas in the paper, such as the low heat leaks of the terminal cryostat and the cryogenic pipe, and the low circulation power, energy storage function of the cable system. In this paper, we present the experimental results of the CASER-2, and discuss and estimate the performance of the system and several ideas. These discussions include the specification of the future long cable system, and show the subjects to solve for the future system. [Copyright &y& Elsevier]

Abstract: In the present experiments three straight high temperature superconducting BSCCO tapes were set parallel to each other on a board and the currents were fed to the tapes. The critical currents of the tape which was set between two tapes were measured with respect to the gap between the tapes. We observed that the critical current increases with decreasing the gap. The calculation of the magnetic flux lines around the tape by finite element method demonstrates the effect on self magnetic field by the adjacent tapes. We could provide some hints on how to arrange the tapes in the power cable for DC power transmission. [Copyright &y& Elsevier]

Abstract: A second cooling test of CASER2, the 200m class superconducting direct current power transmission system at Chubu University, was performed from August to October 2010. During this time, the system was cooled down and the liquid nitrogen which cooled the superconducting power cable was circulated in the cryogenic pipe of CASER2. The heat leak of the cryogenic pipe was measured and the values of about 300W was obtained. This result will be used further improvements of CASER2. [Copyright &y& Elsevier]