• 한국초전도ㆍ저온공학회논문지
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• 제11권3호
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• pp.10-14
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• 2009

Since a stabilizer of YBCO coated conductor (CC) plays a very important role of bypassing over-current and transferring heat generated in the moment of fault, it is one of big issues to determine the material of the stabilizer and its dimension for the high performance of the HTS power application system. Especially, in the case of a superconducting fault current limiter (SFCL), which requires it to react immediately to the occurrence of fault, characteristics of stabilizer are decisive in limiting fault current and recovering superconducting properties during and after quenching. In this paper, the quench / recovery characteristics of YBCO CCs with various thickness of stabilizer were analyzed. The quench/recovery test carried out at 20 $V_{rms}$, 5 cycles (60 Hz) and results showed that as the thickness of the stabilizer decreased, both the final approach temperature and the recovery time decreased.

• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.20-23
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• 2005

The Resistive Type High Temperature Superconducting Fault Current Limiter (SFCL) has been developed in many countries. Until now, materials of the resistive SFCL were Bi2212 bulk and YBCO thin film. Although YBCO coated conductor (CC) has many advantages such as high n-value and critical current for applying resistive SFCL, the resistive SFCL using CC doesn't have developed yet. The bifilar winding type SFCL was manufactured and tested rated on 30V/80A. In normal state, the SFCL using pancake type bifilar winding had very low impedance. When a fault occurred, the SFCL limited the fault current efficiently. Through these results of experiment, large-scale SFCL using CC should be developed in the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.635-636
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• 2008

현재 고온 2세대 YBCO CC(Coated Conductor) 초전도 선재를 사용하여 초전도 전력기기를 제작하게 되면 BSCCO 선재보다 많은 전류를 인가할 수 있지만, 자화 손실도 더 많이 발생하게 된다. 본 논문에서는 폭 12 mm YBCO CC선재를 이용하여 자화 손실을 줄일 수 있는 몇 개의 샘플을 제작하고, 먼저 각 샘플에 대해 외부에서 수직으로 (${\theta}=90^{\circ}$) 가해지는 자장 값에 대한 자화 손실을 측정하였다. 그 후에 측정값을 이용하여 임의 방향으로 가해지는 자장 값들에 대한 자화 손실을 계산하고, 측정한 값과 비교하여 자화 손실의 패턴을 확인하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제6권3호
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• pp.12-15
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• 2004

There are two major approaches to obtain texture template for HTS coated conductor (CC) ---IBAD and RABiTS. CC's with IBAD template showed both longer and higher Ic results so far. IBAD for CC began with YSZ, the processing of which is very slow compared to other processings needed for the fabrication of CC. Because of this very slow processing speed, IBAD with other materials such as Gd$_2$Zr$_2$O$_{7}$(GZO) and MgO have been developed. The processings of IBAD-GZO and IBAD-MgO are known to be up to 3times and 100 times. respectively, as fast as the processing of IBAD-YSZ. IBAD-MgO is very attractive in that the processing is very fast. IBAD-MgO also needs additional buffer layer(s). Many materials are being investigated to be used as a buffer layer on top of the MgO. BaZrO$_3$ (BZO) is a good candidate as the buffer layer on top of the IBAD-MgO because it is chemically stable and does not react with YBCO at high temperatures. It also has good lattice match with MgO. The BZO film has been deposited on single crystal MgO, and YBCO film was deposited on BZO/MgO to investigate the possibility of using BZO as both the buffer and capping layer of the CC.C.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.633-634
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• 2008

본 논문에서는 안정화 층이 없는 YBCO CC(Coated Conductor)의 YBCO층을 임의의 수로 분할한 경우에 대하여 전기적인 특성을 알아보기 위해 각 소선의 임계전류 값을 측정하는 방법을 제안하였다. 안정화 층이 없음으로 통전 중 주울 열에 의한 선재의 소손을 막기 위해 전류를 펄스파 형태로 인가하여 측정하였으며, 선형적으로 전류를 인가하는 측정 방법에 의한 결과와 비교하였다. 결과적으로 안정화층이 없는 경우의 전기적 특성 측정을 위해서는 본 논문에서 제안한 방법이 우수함을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.816-817
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• 2008

본 논문에서는 2세대 고온초전도 선재인 YBCO CC(Coated Conductor)를 사용하여 접합 없이 권선되는 새로운 형태의 고온초전도 팬케이크형 코일에 영구전류를 인가하기 위한 영구전류 스위치의 형태를 제안였다. 제안된 테이프 형태의 광폭 YBCO CC의 양끝부분을 제외한 중간부분을 2분할하여 감아 뒤집은 형태의 팬케이크 코일에는 접합부분이 없으므로 영구전류가 흐를 수 있으나, 전류의 인가를 위한 스위치를 별도로 제작하여 연결하기 곤란하다는 단점이 있다. 본 연구에서는 감아 뒤집은 고온초전도 팬케이크 코일의 한쪽 단부를 영구전류 스위치로 사용할 수 있는 구조를 제안하였고, 추후 연구에 실제로 사용될 12 mm 폭의 YBCO CC를 사용하여 영구전류 스위치를 제작하고 특성시험을 수행하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.9-13
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• 2007

Coated conductor(CC) is recently in actively progress for the research and development, and its can be used various stabilizer lot the specific requirements for each application. Among various superconducting applications, coated conductor applied to superconducting fault current limiters(SFCLS) bypasses fault current to its stabilizer, where the surge is abruptly reduced ; thus, stainless steel, which has large resistivity can be a suitable stabilizer for SFCLS. Despite high n-value of the YBCO, CC stabilized with stainless steel did not effectively limit the first peak fault current. In the short circuit test results of AMSC's 344S, a half period delay was observed between the fault and the generation of resistance(60Hz). In this paper, we performed short-circuit experiments with stacked and unstacked CC and compared the test results to analyze effective fault current limiting characteristics. we compared time of the generated resistance as the fault current limiting characteristics and made the samples one is the stacked CC and the other is unstacked CC. These samples were used equal numbers of pieces of CC. In addition, comparison and analysis was made for the stacked structure by measuring fault current limiting characteristics with respect to thermal insulation by impregnating with epoxy resin.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.806-807
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• 2008

2세대 고온초전도 선재는 전기적, 기계적 특성이 1세대 고온초전도 선재보다 더 우수하지만, 1세대 고온초전도 선재보다 더 높은 교류손실 밀도를 발생시킨다는 단점이 있다. 본 논문에서는 2세대 초전도 선재인 박막형 YBCO CC(Coated Conductor)에서 발생하는 교류 손실을 감소하기 위한 방법으로 선재의 초전도층을 분할하여 단면의 종횡비를 줄이는 방법을 제안하였으며, 실제로 제작 및 특성 측정을 통해 제안된 방법의 타당성을 보였다. 박막형 선재의 초전도층을 분할하기 위해 포토마스킹을 이용한 에칭 방법을 이용하였다. 샘플의 제작을 위해 안정화층이 없는 폭 12mm 의 YBCO CC를 사용하여 샘플의 길이는 15cm로 하고 선재의 분할수를 다르게 하여 각 샘플에 대한 자화 손실과 각 소선의 임계전류를 측정한 후 선재의 전기적 특성 변화를 알아보았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1222-1224
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• 2005

AC loss is an important factor in the development of superconducting tapes and superconducting power applications. In this paper, magnetization loss in YBCO coated conductor have been measured and compared with Brandt equation. Measurements of magnetization loss were performed under various angles of external magnetic field to consider the anisotropic characteristics of YBCO coated conductors. The results show that measured values of magnetization loss agreed well with the calculated value by using Brandt equation, especially at large degrees of incidence angle. The magnetization losses were strongly influenced by the direction of external magnet field as were expected.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.47-52
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• 2007

This paper presents characteristics analysis of persistent current switch(PCS) system on a small scale by using YBCO coated conductor(CC). A high temperature superconductor(HTS) PCS system mainly consists of a PCS, a HTS magnet load and a magnet power supply(MPS). To design the optimal heater triggering switch. the three-dimensional heat conduction model was analyzed by finite element method(FEM). The electrical equivalent model considering the n-value of CC was applied to analyze current decay during persistent current mode. In the experiment and simulation, the heater was applied with a current of 0.43A and the current was ramped up to 10A and 20A with 0.2A/s. Finally, experimental results of the HTS PCS system have been compared with the theoretical results. It has been concluded that flux creep can not influence the results because the operating current was 40% of critical current and optimal sequential operation of the PCS system is indispensable to enhance its performance.