• Progress in Superconductivity
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• v.3 no.2
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• pp.235-240
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• 2002

In this paper, we investigated the current limiting characteristic in the magnetic shielding type fault current limiter(MSFCL). The circuit analysis was executed by using finite differential method(FDM). This paper suggests that the current limiting performance can be achieved in two ways (resistive and inductive one), according to design parameter. By comparing current limiting characteristics in two ways and surveying the important parameters which determine the operational way after fault occurs in the design of MSFCL, it is shown that the magnetic shielding type fault current limiter can be operated in either resistive or inductive way.

• 한국초전도학회:학술대회논문집
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• v.11
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• pp.71-71
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• 2001

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.37-42
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• 2007

We are developing a 22.9 kV/25 MVA superconducting fault current limiting(SFCL) system for a power distribution network. A Bi-2212 bulk SFCL element, which has the merits of large current capacity and high allowable electric field during fault of the power network, was selected as a candidate for our SFCL system. In this work, we experimentally investigated important characteristics of the 190 kVA Bi-2212 SFCL element in its application to the power grid e.g. DC voltage-current characteristic, AC loss, current limiting characteristic during fault, and so on. Some experimental data related to thermal and electromagnetic behaviors were also compared with the calculated ones based on numerical method. The results show that the total AC loss at rated current of the 22.9 kV/25 MVA SFCL system, consisting of one hundred thirty five 190 kVA SFCL elements, becomes likely 763 W, which is excessively large for commercialization. Numerically calculated temperature of the SFCL element in some sections is in good agreement with the measured one during fault. Local temperature distribution in the190 kVA SFCL element is greatly influenced by non-uniform critical current along the Bi-2212 bulk SFCL element, even if its non-uniformity becomes a few percentages.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.105-108
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• 2002

In this paper, we investigated the fault current limiting characteristic of flux-lock type High-Tc superconducting fault current limiter(HTSC-FCL), which is comprised of a flux-lock reactor and an external magnetic field coil covering the HTSC element In this HTSC-FCL, the initial limiting current level can be controlled by adjusting the inductance of the each coil. Furthermore, the fault current limiting characteristics of HTSC-FCL can be improved by applying 'the external magnetic field into the HTSC element We performed the computer simulation by numerical analysis about the flux-lock type HTSC-FCL and compared the results of experiment with simulation ones. We can obtain the same results from both the computer simulation and the experiment except for the time immediately after fault occurs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.995-999
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• 2007

We investigated the characteristics of a flux-lock type superconducting fault current limiter(SFCL) considering magnetization characteristic of iron core. The flux-lock type SFCL, like other types of SFCLs using the iron core, undergoes the saturation of the iron core during the initial fault time. Therefore, if the design to prevent the saturation of the iron core is considered, the effective fault current limiting operation can be achieved. Through the analysis for its equivalent circuit including the magnetization characteristic of the iron core, the limiting impedance of the flux-lock type SFCL was drawn. The magnetization currents and the limited currents of SFCL, which were dependent on the winding direction and the turns' ratio between two coils, were investigated from the short circuit experiment. It was confirmed that their experimental results agreed with the analysis ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.511-514
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• 2002

In this paper, we compared the characteristic of fault current liminting in the magnetic shielding type High-Tc superconducting fault current limiter(FCL) using both Piecewise linear magnetization curve and real magnetization one of iron core. From this paper, the characteristics of fault current limiting in both cases showed many differences. The latter has higher fault current than the former, because the saturation of iron core was reflected and more accumulated during fault. It is expected that the more exact characteristic of magnetic shielding type High-Tc superconducting FCL was obtained in the case of design and modeling.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.370-374
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• 2005

AC loss of a superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in power systems. Therefore, the AC loss characteristics in several fault current limiting elements of a coil type have been investigated experimentally. The test result shows that AC losses measured in the fault current limiting elements depend on arrangement of a voltage lead. The AC loss of a bifilar coil is smallest among the fault current limiting elements of the coil type. The measured AC loss of the bifilar coil is much smaller than that calculated from Norris's elliptical model. However, the loss measured in a meander, which is frequently used in a resistive fault current limiter, agrees well to the theoretical one.

• Progress in Superconductivity
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• v.3 no.2
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• pp.252-256
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• 2002

We studied YBCO films for current limiting of the resistive type which utilizes a transition from superconducting to normal state caused by exceeding critical current. The films were deposited on sapphire substrates and covered by gold top layer. The current limiting element consists of 2 mm wide YBCO stripes connected in series. A serious problem in using YBCO films for current limiting is inhomogeneities caused by imperfect manufacturing. Therefore simultaneous quench is a difficult problem when elements for current limiting are connected in series. So some researchers have recently proposed using magnetic field and heating for simultaneous quench. We have measured extended exec trim field-current density(E-J) characteristics for current limiting elements of YBCO films in applied magnetic field of 0 - 130 mT. And we have investigated quench characteristics in current limiting elements and between elements of YBCO films in applied magnetic field. The result of the experiments show that the presence of applied magnetic fields induces uniform quench distribution fur the stripes in element at $50V_{rms}$, otherwise non-uniform quenches were observed. And simultaneous quenches between elements were investigated at $150V_{rms}$. We suggest that suppressing the critical current by increased fields due to fault current effectively forced the stripes of higher $J_{c}$(0) to quench, resulting in equalizing quench times.s.s.s.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.11
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• pp.75-80
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• 2012

In this paper, the operational characteristics due to the introduction of the superconducting fault current limiter(SFCL) with a peak current limiting function were analyzed in the power distribution system. The parallel structure of the superconducting element can operate the peak current limiting function depending on the transient amplitude of fault current. We studied the operating characteristics of the introduction of the SFCL with a peak current limiting function in the power distribution system. Furthermore, we were analyzed between the SFCL with a peak current limiting function and the protection devices in the power distribution system, through the short circuit experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.39-40
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• 2007

The analysis of fault current limiting characteristics according to variation of fault current level in the integrated three-phase flux-lock type superconducting fault current limiter (SFCL), which consisted of three-phase flux-lock reactor wound on an iron core with the same turn's ratio between coil 1 and coil 2 for each single phase, was performed. To analyze the current limiting characteristics of this integrated three-phase flux-lock type SFCL, the short circuit experiments was carried out the various three-phase faults such as the single line-to-ground fault, the double line-to-ground fault, the triple line-to-ground fault. From the experimental results, the fault current limiting characteristic was improved according to increase of fault current level.