• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.83-88
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• 2006

AC loss is one of the main research area in AC power application using high temperature superconductor(HTS), such as HTS transformer, HTS current limiter and HTS cable, because it is closely related to efficiency, economic estimation and design of power device. A lot of research for various arrangements of HTS tapes have been performed to increase a capacity of transport current because single HTS tape can not satisfy the demanded current capacity in HTS power application. In this paper, we studied magnetization loss by different several arrangements of BSCCO tapes such as Edge-to-Edge type, Face-to-Face type and Matrix type through numerical analysis by 2D-FEM and measurement. As a result, we got the result that the magnetization loss of Face-to-Face type arrangements was lower than those of other arrangement types under the conditions of the same stacking number. We think that the result was due to shield effect by demagnetization of adjacent HTS tapes which are located face to face.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.218-221
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• 2000

Currently, Bi-2223 HTS tape is capable of being fabricated in longer than 100m length by industrial processes. But there are some problems in heat treatment of the degree of longer than 100m tape, which is in term of volume occupied with specimen in furnace. The effects of ceramic coating with variable slurry states were studied in Bi-2223 high-temperature superconductor. The HTS tapes coated with oxide were prepared by using dip-coating method on slurry state. Critical current(I$_{c}$) of tapes coated with ceramic materials were equal with 11.5A at 77K after first heat treatment as different slurries. For final heat treatment, Critical current of HTS tapes coated with zirconia oxide mixed in PMMA and PVA organic solute were 20.8A at 77K. The breakdown voltage of HTS tapes coated with zirconia oxide were 3kV in air and 4~7kV in L$N_2$.>.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.32-36
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• 2010

Superconducting current leads are indispensible for reducing power loss when subjecting current into superconducting magnets. HTS(High-Tc superconducting) current leads are divided into two types; one is bulk type and the other is tape type. In this paper, conceptual design on the HTS current leads which adopts tape type for nuclear fusion magnets is carried out using magnetic field analysis and thermal analysis. When large current flows through superconducting current leads, strong self magnetic field is generated and applied to the superconducting tapes. This phenomenon leads to the critical current decrease of the superconducting tape. Therefore, we analyzed magnetic field distribution of current leads and found the proper arrangement with respect to the various HTS tapes. In addition to the magnetic field analysis, heat leak through the current leads was also calculated to know which HTS tape is superior than others in thermal aspect. Magnetical field analysis and calculation of heat leak are performed to design 2 kA class HTS current leads.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.274-277
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• 2003

Critical current(Ic) degradation of HTS tapes after bending is one of the hottest issues in HTS development and application studies. Many people are measuring Ic degradations for effect of bending radius. However even if the bending radius is larger than the breaking radius a HTS tapes can be damaged by repetitive bending, which is unavoidable in the winding processes. Therefore, We studied the Ic degradation after repetitive bending. at 77K with self-field, of Bi-2223 tapes processed by "Powder-in-Tube" technique, which was made by America Superconductor Corporation(AMSC) and superconductiing tapes that strain is imposed measured critical current by temperature difference of L$N_2$ and normal temperature. Like this, critical current could measure that degradation about 1~3％ by temperature difference. These results will amount the most important basis data in power electric machine of superconductivity cable, magnet, etc that winding work is require.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.678-682
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• 2004

Generally Bi-2223/Ag tapes have a broad S/N transition region and their sheath is a good electric conductor. In this study, the current distribution between superconductor and metal sheath in HTS tapes were investigated. AC with its peak value above 10 times $I_{c}$ was applied to HTS tapes for around 6 cycles and V-I characteristics were measured. Using the resistance of the sheath and V-I curves, the current distribution between superconductor and metal sheath was calculated. When 150 $A_{p}$ was applied, more than 2/3 of the current flows through superconductor. However, in the case of 304 $A_{p}$, most of the applied current came to flow through the metal sheath at the 6th cycle.e.e.e.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.235-238
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• 2000

There have been a lot of studies to improve the characteristic of Bi-2223 tape by PIT method which is considered as one of the best way for applying superconductor. These improved characteristic of Bi-2223 tape is able to be acqured by control of mechanical deformation and heat treatment. In this work, we studied HTS tapes with the sheath(Ag and Ag-alloy)of tapes that affect mechenical strength and critical current, with each two kind of purity(99.9% and 99.999%) and with two kind of tapes(single and double concentric). These charateristics affect Jc of tapes seriously that is the most important factor of superconductor tapes.

• Proceedings of the KIEE Conference
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• summer
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• pp.776-778
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• 2004

In this paper, we present effect of the stacked HTS tapes. AC losses of HTS pancake windings with stacked tapes are shown. Magnetic flux density in the HTS winding under operating conditions was calculated by FEM. AC loss of the pancake winding were measured and compared with the calculated loss by using AC losses of the stacked samples. Test results show that measured results generally agreed well with the calculated value by using AC loss of 4-stacked sample data.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.48-51
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• 2003

HTS power transmission cable is expected to transport large electric power with a compact size. We are developing a 3-core, 22.9 kV, 50 MVA class HTS power cable, and each core consists of a conductor and shield wound with Bi-2223 tapes, electrical insulation with laminated polypropylene paper (LPP) impregnated with liquid nitrogen. This paper describes the design and experimental results of the model cable for the 22.9 kV, 50 MVA class HTS power transmission cable. The model cable was used the SUS tapes instead of HTS tapes because of testing the electrical characteristics only. The model cable was 1.3 m long and electrical insulation thickness was 4.5 mm. The model cable was evaluated the partial discharge (PD), AC and Impulse withstand voltage in liquid nitrogen. The AC and Impulse withstands voltage and PD inception stress was satisfied with the standard of Korea Electric Power Corporation (KEPCO) in the test results. The 3-core 22.9 kV, 50 MVA class HTS power cable has been designed and manufactured based on these experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.1
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• pp.23-26
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• 2003

This paper presents conceptual design and 3-D electromagnetic analysis of IMVA transformer with BSCCO-2223 High Tc Superconducting (HTS) tapes. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV, and double pancake windings were adopted. High voltage and Low voltage sides were composed of several double pancake windings. Four HTS tapes were wound in parallel for the windings of low voltage side and were transposed in order to distribute the currents equally in each conductor The transformer core was designed as a shell type core made of laminated silicon steel plates and the core is separated with the windings by a cryostat with Fiberglass Reinforced Plastics(FRP). A sub-cooling system using L$N_2$ were designed to maintain the coolant temperature 65K. Finally perpendicular components of magnetic field applied to tapes were calculated 0.247 in the rated operation using 3-D analysis. A real 1MVA HTS transformer will be manufactured in near future based on the design parameters presented in this paper.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.280-284
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• 2000

The prototype high-T$_c$ superconducting (HTS) power transmission cables have been designed and fabricated multi layers of spirally wound HTS tapes. The cables were made Bi-2223 based Ag-sheathed HTS tapes, and tested in LN$_2$. Critical currents of 700A dc and better were achieved. The magnetic flux density and field direction were analyzed in the cable configuration. In this paper the results of analysis and tests of HTS power transmission cables were described.