• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1228-1230
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• 2005

This paper deals with design of heater trigger switching in a persistent current system(PCS) by finite element method(FEM) analysis of YBCO coated conductor(CC) tape. Most promising superconducting wire is YBCO coated conductor tape in these days for its high n value and critical current independency from external magnetic field. It is expected to be used many superconducting application such as fault current limiter and cable etc. The superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as a high uniformity of a magnetic field and reducing a thermal loss. A PCS system consists of magnet power supply (MPS) which energized current to a magnet, heater, a coated conductor tape for switching, and superconducting magnet. In this paper, the characteristic of thermal quench of the YBCO CC tape and BSCCO tape by heater trigger analyzed by FEM. And optimal length of heater is calculated by temperature and time analysis. This heater trigger analysis is expected to be a basic concept of PCS application design.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.603_604
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• 2009

HTS tape is developed for the purpose of being applied to the power cable, motor and generator, etc. The resistance of conventional power cables is not changed a lot by over current condition. But HTS(High temperature superconductor)power cable has some different properties. The impedance of superconductor is changed due to the magnitude of current, temperature, and magnetic field. And the characteristics analysis of HTS power cable under many kind of fault conditions are important to apply real system. In addition the magnitude of over current is 10 times larger than rated current. In this paper, the characteristics of HTS power cable are analyzed when over current flows. Model cable used 2G wires was made and experimented. The results will be helpful to manufacture real HTS power cable.

• Progress in Superconductivity and Cryogenics
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• v.14 no.3
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• pp.9-12
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• 2012

Usually, the AC loss from the superconducting element of an SFCL due to the load current is very small because it is composed of the combination of bifilar windings with very small reactance. Although the AC loss is small enough, we should be albe to predict for the design and control of the cryogenic system. In fact, an SFCL for the transmission voltage class may not generate ignorable AC loss because of the inevitable space between the HTS wires for the high voltage insulation and cryogenic efficiency. To measure the AC loss dependency on the space between the 2G HTS wires with the width of 4.4 mm, we prepared an experimental setup which could adjust the distance between the wires. We used two 500-mm length HTS wires in parallel and applied the current in the opposite direction for each wire to simulate a part of a current limiting module for a high voltage SFCL. We also put two couples of voltage taps at the ends of each wire and a cancel coil in the voltage measurement circuit to compensate the reactive component from the voltage taps. In this condition, we varied the distance between the wires to investigate the change of the transport current loss. A similar experimental study with HTS wire with the width of 12 mm is now in progress.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.161-162
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• 2005

2G HTS coated conductor wire consists of textured substrate, buffer layer, superconduct layer, Ag cap layer, stabilizer. For practical application filed, coated conductor have mechanical and electrical stability and environment protection properties. This property Cu and stainless steel strip is laminated to Ag cap layer as stabilizer materials. Lamination process join stabilizer material strip and Ag cap layer with soldering method. we have laminated HTS with continuous dipping soldering process different stabilizer Cu and stainless steel strip and changed lamination process condition. The effect of lamination stabilizer and process condition has been investigated mechanical and electrical properties.

• Progress in Superconductivity
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• v.12 no.2
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• pp.118-123
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• 2011

The properties of $2^{nd}$ generation high temperature superconducting wire, coated conductor strongly depend on the quality of superconducting oxide layer and property of metal substrate is one of the most important factors affecting the quality of coated conductor. Good mechanical and chemical stability at high temperature are required to maintain the initial integrity during the various process steps required to deposit several layers consisting coated conductor. And substrate need to be nonmagnetic to reduce magnetization loss for ac application. Hastelloy and stainless steel are the most suitable alloys for metal substrate. One of the obstacles in using stainless steel as substrate for coated conductor is its difficulties in making smooth surface inevitable for depositing good IBAD layer. Conventional method involves several steps such as electro polishing, deposition of $Al_2O_3$ and $Y_2O_3$ before IBAD process. Chemical solution deposition method can simplify those steps into one step process having uniformity in large area. In this research, we tried to improve the surface roughness of stainless steel(SUS310). The precursor coating solution was synthesized by using yttrium complex. The viscosity of coating solution and heat treatment condition were optimized for smooth surface. A smooth amorphous $Y_2O_3$ thin film suitable for IBAD process was coated on SUS310 tape. The surface roughness was improved from 40nm to 1.8 nm by 4 coatings. The IBAD-MgO layer deposited on prepared substrate showed good in plane alignment(${\Delta}{\phi}$) of $6.2^{\circ}$.