• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.418-423
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• 2003

AC loss is an important issue in the design of high-T$\sub$c/ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. So special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The critical current and AC loss characteristics in the conductor have experimentally investigated. The results show that for uniform current distributions the conductor's critical current is proportional to the critical current of the Bi-2223 tape to which a voltage lead is attached. However it depends on the current non-uniformity parameter in the conductor rather than the tape's critical currents for nonuniform current distributions. The loss tests indicate that the AC loss is dependent on arrangements of voltage leads but not on their contact positions. The measured losses in the conductor also agree well with the sum of the transport losses measured in each Bi-2223 tape.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1035-1038
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• 2007

We designed and manufactured a 1.8T high temperature superconducting(HTS) insert coil for a NMR magnet operated at 4.2 K. Suitable HTS superconductor and HTS coil were carefully designed and developed. We have selected multi-filamentary Bi2223 conductor fabricated by American Superconductor Corporation(AMSC). The selected conductor consists of Bi2223 filaments of 55, silver stabilizer and stainless steel reinforcement tapes. Therefore, it shows good hoop strength as well as compression tolerance. The conductor has a tape cross-section of 0.31mm x 4.8mm. the Bi2223 conductor shows large anisotropy of critical current. The critical current of conductor in magnetic field parallel to the flat surface are much higher than that in magnetic field perpendicular. The HTS coil has an inner diameter of 78 mm, an outer diameter of 127 mm and a coil length of 600 mm. In this paper, the detailed design, fabrication and test results on the HTS insert coil are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.448-451
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• 2000

Normal zone propagation(NZP) characteristics were investigated on Ag sheathed Bi-2223 tape and cylindrical stacked conductor. Normal zone propagation(N2P) experiments with tape were conducted with refrigerator in temperature from 45 K to 77 K, 0 T. Cylindrical stacked conductor was molding with epoxy and experiments were conducted with adiabatic condition in $LN_2$. NZP velocities of tape with two condition of DC and AC were almost same at each temperature. NZP velocities of cylindrical stacked conductor were 1.9-2.4 cdsec in $LN_2$. Numerical analysis was carried out by a one-dimensional heat balance equation. As a result, simulated results of NZP velocity with Bi-2223 tape were similar to experimental results in DC.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.29-34
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• 2001

A Bi-2223 tape has been developed for low-field Power applications such as Power cables or transformers working at liquid nitrogen temperature For such applications it is required to understand fault current characteristics of the Bi-2223 tape. In this paper we report fault current characteristics using two types of samples, straight sample and pancake coil sample. It was found that the fault current characteristics of the Bi-2223 tape are independent of external fields and frequencies . However they depend on electrical insulations and fault durations strong1y Also it was shown that the fault current characteristics in the insulated straight sample are similar to those in the pancake sample with a conductor insulation. Finally. it was shown that the Pancake sample with a layer insulation has better characteristics than that with a conductor insulation fur fault currents.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.46-49
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• 2002

The ac loss is an important issue in the design of superconducting cables and transformers. In these devices the Bi-2223 tapes are usually placed face-to-face In such arrangements ac loss is influenced by adjacent tapes. The effect is investigated by measuring the magnetization loss in the stacked conductor, which consists of various numbers of Bi-2223 tapes. For the stacked conductor in perpendicular field the magnetization loss at low fields is greatly decreased, compared to the loss of the single tape. The loss at high fields is unaffected. This behavior is well described by the slab model.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.792-794
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• 2003

AC loss is an important issue in the design of high-$T_c$ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The critical current characteristics in the conductor have experimentally investigated. The results show that for uniform current distributions the conductor's critical current is proportional to the critical current of the Bi-2223 tape to which a voltage lead is attached. However it depends on the current non-uniformity parameter in the conductor rather than the tape's critical currents for nonuniform current distributions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.10
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• pp.554-559
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• 2002

The at loss is an important issue in the design of superconducting cables and transformers. In these devices the Bi-2222 tapes are usually placed face-to-face. In such arrangements ac loss is influenced by adjacent tapes. The effect is investigated by measuring the magnetization loss in the stacked conductor, which consists of various numbers of Bi-2223 tapes. For the single tape the magnetization loss in perpendicular field is larger than that in parallel field by about a factor 10. This agrees well with the prediction for hysteresis loss in slab and strip models. For the stacked conductor in perpendicular field the magnetization loss at low fields is greatly decreased, compared to the loss of the single tape. However the loss at high fields is nearly unaffected. This behavior is well described by the slab model.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.206-209
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• 2003

AC loss is an important issue in the design of high-T$_{c}$ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. So special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The ac loss characteristics in the conductor have experimentally investigated. The loss tests indicate that the ac loss is dependent on arrangements of voltage leads but not on their contact positions. The measured losses in the conductor also agree well with the sum of the transport losses measured in each Bi-2223 tape.e.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.7-10
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• 2003

AC loss is an important issue in the design of high-T$_{c}$ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. So special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The ac loss characteristics in the conductor have experimentally investigated. The loss tests indicate that the ac loss is dependent on arrangements of voltage leads but not on their contact positions. The measured losses in the conductor also agree well with the sum of the transport losses measured in each Bi-2223 tape.e.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1240-1242
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• 2005

In this study, we estimate the transport current loss of Bi-2223/Ag tapes with non-uniform current distribution. The conductor was consisted of three Bi-2223/Ag tapes and the each tapes were attached in parallel. The loss of conductor was investigated both numerical and experimental methods. The numerical code to predict ac loss was developed, and finite element method was introduced. It contained intrinsic properties of superconducting tape, which was obtained from nonlinear current voltage relation with external magnetic field and its orientation. Two results were compared and discussed. They showed good agreements with each other.