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The High Temperature Superconducting (HTS) electric equipment using Bi-2223 wire successfully commercialized 1st generation HTS wire, has been developing by many research groups. HTS coil is one of the most important parts in HTS electric equipment. To enlarge the critical current, the operating temperature of the equipment tends to go down and number of HTS wire tends to increase. Thus, it is very important to determine the whole critical current of HTS coil for the stable operation of HTS equipment. The whole critical current of multi-stacked wire of HTS solenoid coil is not equal to the sum of the critical current of each stacked wire because of nonuniform current sharing occurs in multi-stacked HTS wires and each HTS path does not has the same critical current. In this paper, current sharing in two types of 5-stacked HTS solenoid coils, made up of 1 copper layer which is a current buffer layer of HTS coil and 4 HTS wire layers, was analyzed. One was wound with Bi-2223 wire insulated with polyimide tape and the other was wound with noninsulated Bi-2223 wire. All of the Bi-2223 wires were reinforced with stainless steel. The simulation results of current sharing in multi-stacked HTS coils coincided well with the experimental results. Based on these results, the current sharing ratio of large scale HTS coil was also expected. The copper layer acted as a good current path when all the HTS wires were quenched. [ABSTRACT FROM AUTHOR]

Abstract: For the design of superconducting fault current limiter, the research about recovery time and AC loss is essential issue because this characteristic is closely related to stability and efficiency. In general, superconducting fault current limiter (SFCL) modules can be made into pancake or solenoid type coil. While the pancake type coil has smaller AC loss, it has longer recovery time compared with the solenoid type coil. In this paper, a new pancake type coil was proposed to decrease recovery time by improving their cryogenic condition. A new pancake type coil is made with spacers between adjacent superconducting tapes. However, as the thickness of the spacer was increased, the AC loss was increased unlike the recovery characteristic. From the experimental results, our group confirmed that the pancake type coil with the spacer has trade-off relationship between AC loss and recovery characteristics with the spacer thickness. The proposed results in this paper would be utilized to design superconducting fault current limiters. [Copyright &y& Elsevier]

The high-Tc superconducting (HTS) magnet is an important element for developing HTS power equipments such as the dc reactor of the inductive type superconducting fault current limiter (SFCL). In order to use the HTS magnet for the large-scale power system, its critical current needs to be high enough. Generally, the double pancake HTS magnet has the severe decrease in the critical current because of magnetic field perpendicular to the tape surface. To fabricate a high critical current magnet, we wound a solenoid with the stacked tape. In this paper, the characteristics of the critical current of the HTS solenoid wound with the stacked tape were investigated. The results of this research can be used as the background data for the design of the large-scale HTS magnet. [Copyright &y& Elsevier]