• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.527-530
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• 2002

A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. In this paper, initial annealing of Bi-2223/Ag wire to transform Bi-2212 orthorhombic from Bi-2212 tetragonal Precursor was investigated. This initial annealing step at low oxygen partial pressure were to transform Bi-2212 orthorhombic structure and to reduce the formation of second phases at superconducting wire. However Bi-2223 Phases were appeared at higher annealing temperature. Critical currents(Je) of Bi-2223/Ag tapes were sintered at low oxygen Partial pressure were higher than that of the wires sintered at atmosphere condition. In order to investigate the effect of rolling reduction ratio, Bi-2223/Ag HTS tapes were rolled with different reduction ratio. There were no clear difference of Je and filaments shape with various rolling reduction ratio.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.32-36
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• 2005

With the successful commercialization of Bi-2223 powder-in-tube wire , various attempts in the R & D of the high-Tc superconducting (HTS) magnets for high magnetic field applications are being implemented actively. Operating temperature of HTS magnet has to be maintained at the designed level but the magnetic energy and mechanical disturbance can cause unstable operational temperature of HTS magnet. Especially the generated heat energy of inner HTS winding Is apt to be accumulated . so the normal region appears in HTS winding. This paper deals with the quenching characteristics of three kinds of selected Bi-2223 wires : the High Current Density Wire (HC-A) and the High Strength Wire (HS-A) made by AMSC and HTS wire(HW-I) made by Innost The Innost wire has the highest minimum quench energy (MQE). The High Current Density Wire has the highest normal zone Propagation velocity (NZPV).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.55-58
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• 2002

PIT method which is used at fabricating Bi-2223/Ag HTS wire includes a drawing process, conventional deformation method. Drawing of meta1(Ag) and ceramic (BiSrCaCuO) composite is also difficult and significant for uniform deformation. In this paper, parameters of uniform deformation was studied at Bi-2223/ Ag multifilamentary HTS wire. Powder and rod as a starting precursor was compared at 55 filament and 54 filament Bi-2223/Ag HTS wire, respectively. Micro-hardness and area COV of the filaments was also evaluated when the diameters were decreased through drawing operations.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.31-34
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• 2005

There are many kinds of high temperature superconducting (HTS) application using Bi-2223 tape which is the most commercialized HTS material. Also, resistive superconducting fault current limiters (SFCLs) have been developed using many kinds of superconducting material such as YBCO thin film, Bi-2212 bulk and so on. However, SFCL using Bi-2223 tape has never been developed. This paper deals with the feasibility study on SFCL using Bi-2223 wire. The over-current behaviors of Bi-2223 short-length sample were measured. To make the resistive SFCL, two small-scale bifilar winding modules using 7m Bi-2223 wire were fabricated; i.e. solenoid type bifilar coil and pancake type one. The short-circuit tests of the coils were successfully performed up to 16 V$_{rms}$ From these tests, the current limiting capabilities of Bi-2223 bifilar coils were confirmed and current limiting performances between two winding types were compared. In addition, the feasibility of resistive SFCL using another HTS wire, i.e. YBCO coated conductor, was also investigated.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.65-67
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• 2003

The critical current of Bi-2223/Ag HTS wire could be improved by the second phase modification pre-treatment (SPMT). On the other hand, the pre-treatment conditions are possible to affect to the degradation of silver alloy sheath, such as brittleness. Chlorine was detected at the outer sheath of wire by Auger observation, we also have tried to search new pre-treatment conditions that do not affect the degradation of silver sheath but, improve the critical current of the wire.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.67-73
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• 2002

The development of high performance HTS wire is a key factor for various electrical applications of coils and cables. The purpose of this paper is to review and consider the main manufacturing technologies of HTS wire and its current status. A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. According to this, long Bi-2223 wires having Ic of 130 A were recently produced and their mass production has been underway in US. The current status performance of Bi-2223 wire is supposed to be used in power transmission cable because of its lower self-field property. Y-123 second generation conductor is extensively being developed throughout the world and many fabrication processes are competed with each other. 30 m-long Y-123 wire with Ic of 0.8 MA/$\textrm{cm}^2$ was recently fabricated using IBAD and PLD techniques in Japan. This result offers promise of scalable processing of practical multi-layer coated conductor.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.85-87
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• 2003

Intermediate annealing was carried out during wire drawing for uniform deformation of 500 m class Bi-2223/Ag HTS tapes. Wire drawing force was measured to evaluate the uniformity of wire deformation along the length. To prevent sausage and filament breakage of wire, drawing stress was controlled below 200 MPa by using intermediate annealing process. Thickness and width of the rolled tapes was measured 0.23 mm and 4.1 mm with low deviation $\pm$ 0.08 mm and $\pm$ 0.09 mm, respectively. The critical current of the 500 m tapes was measured 33.7 A $\pm$ 3.7 A by continuous critical current measurement system.

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.20-24
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• 2004

Bi-2223 wire, the first-generation high temperature superconducting (HTS) wire, was successfully commercialized and various electrical machinery and equipment are actively being developed in many countries. Because its critical current is too small to realize the lossless conducting part of electric power system with a HTS wire, multi-HTS paths are used to enlarge the critical current of HTS system. Though the resistance generated in HTS wire by transport current is very small, the difference of it in multi-path is the additional reason which causes the non-uniform current sharing in multi-HTS path except the well known reason, the difference of inductance between each path. In this paper, experimental research on current sharing of multi-strand and multi-stacked HTS wire was implemented. The whole critical current of multi-HTS paths is not equal to sum of critical current of each path because of non-uniform current sharing occurred in this paths. It was verified experimentally that Bi-2223 wires have different resistance generated by same transport current even if they was manufactured in same progress of work. Current sharing phenomenon was affected by difference of resistance and self and mutual inductance.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.12-16
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• 2010

Critical current - magnetic field ($I_c$-B) relation is one of the basic properties of an HTS wire, which is needed for the design of performances of superconducting devices. Experimental results of the $I_c$-B relation of Bi-2223 and YBCO superconducting wire are presented in this paper. n-value is also an important parameter which is needed to calculate the electric field by using the power-law. Measurement results of the n-value of the same HTS superconducting wires are also presented.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.3-5
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• 2000

Among the various processing techniques used in HTS wire fabrication, the PIP(Powder In Tube) method is currently one of the most promising for applications on an industrial scale. In this study, we have fabricated Bi-2223/Ag superconducting tapes using the modified PIT process, where several process factors were changed and improved, ie., powder packing, drawing, rolling and heat treatment. We obtained Bi-2223 tape that have high critical current, 46 a at 77.3 K, have high critical current, 46A at 77.3 K, self field although the tape was not pressed but only rolled. The critical current of 100m class long length tape was measured 21.6A at the same criterion. Besides, the critical current of Bi-2223/Ag tape was measured applying magnetic fields with different directions at various temperatures.