• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.73-77
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• 1990

In this paper we describe the solid-state ac-circuit breaker which has the characteristic of both a half cycle circuit breaker and a current limiting circuit breaker. This circuit breaker has a current limiting resistor in order to surprises the fault current to a certain level and discharge the energe included in circuit inductor. We explain the effect of circuit parameter on transient phenomena of switch device by using EMTP and finally design the control circuit consisted synchronous closing circuit, over- current detecting circuit and sensing circuit of rate of rise of fault current.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.391-396
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• 2005

In this paper the modeling of interrupting characteristics of a high voltage current limiting fuse to be used in a power distribution system is introduced. In order to reduce the level of energy which can be absorbed by equipment during fault current flow, a high voltage current limiting fuse can generate a high voltage at the fuse terminals. Consequently it is necessary to model and analyze precisely the voltage and current variation during a CL fuse action. The characteristics of CL fuse operation modeled by electrical components have been performed with less than 6 [$\%$] errors. So the fuse designer or manufacturer can estimate the characteristics of CL fuse operation by using this modeling. The Electro Magnetic Transient Program (EMTP) is used to develop the modeling.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1298-1305
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• 2016

This paper presents the development of a short-circuit protection mechanism on a high voltage switch (HVS) board which is built by a series connection of semiconductor switches. The HVS board is able to quickly detect and limit the peak fault current before the signal board triggers off a gate signal. Voltage clamping techniques are used to safely turn off the short-circuit current and to prevent overvoltage of the series-connected switches. The selection method of the main devices and the development of the HVS board are described in detail. Experimental results have demonstrated that the HVS board is capable of withstanding a short-circuit current at a rated voltage of 10kV without a di/dt slowing down inductor. The corresponding short-circuit current is restricted to 125 A within 100 ns and can safely turn off within 120 ns.

• Progress in Superconductivity and Cryogenics
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• v.1 no.2
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• pp.49-53
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• 1999

We fabricated a resistive superconducting fault current limiter (SFCL) with a shunt resistor in order to bypass the transient current at faults. The SFCL consists of a YBCO films coated with an Au layer (10$\Omega$ at room temperature). which is to disperse the heat generated at hot spots in the YBCO films, and a 5$\Omega$ shunt resistor. The minimum quench current of the SFCL was found to be 12.2Apeak. This SFCL successfully controlled the fault current to below 23 Apeak. Which is otherwise to increase up to 103 Apeak. With the shunt resistor, the temperature of the SFCL rose the temperature of the SFCL rose three times slower than without the shunt, whereby the SFCL is protected at high currents.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.475-478
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• 2006

In electrical impedance tomography (EIT) an array of electrodes is attached on the boundary of an object and small alternating currents are injected through these electrodes, and then the resulting voltages are measured. An estimation for the cross-sectional resistivity distribution in the object is obtained by using these current and voltage data in a nondestructive manner. In this paper, the electrical impedance imaging of two-phase flows undergoing rapid transient is considered with a special emphasis on the effect of the current pattern on the image reconstruction. The trigonometric current pattern, which is commonly used in the conventional static electrical impedance imaging, shows poor performance in case of the dynamic imaging considered in this work. Extensive numerical experiments are conducted with various kinds of current patterns and their effects on the image reconstruction performance are examined.

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.1-10
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• 2009

This article reviewed transport behaviours of electroactive species in ionic compounds, focusing on chemical diffusion of Li through the transition metal oxide in a current flowing condition. For this purpose, a distinction has been first briefly made between migration and diffusion with respect to current, driving force and charge of electroactive species considered. Then, the equations for chemical diffusion are derived theoretically in open-circuit and current flowing conditions. Finally, the experimental methods such as ac impedance spectroscopy and current (potential) transient techniques are described in details for characterising chemical diffusion. In addition, the role of the thermodynamic enhancement factor in chemical diffusion is discussed.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.185-192
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• 1998

This paper presentsa new currnet control method ofthe six-pulse cycloconverter which is used as a variable speed drive system of a large capacity ac mortor. For a high performance control as a vector control, it is necessary that the output current control ofthe power converter has a good characteristic in transient state. A new proposed current control method is that the output current of a cycloconverter is followed after the current reference directly as fast as possible under any condition. Simultion results for the proposed new current control method are shown and its validity of the proposed method is confired.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.268-271
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• 2000

We simulated the current limiting characteristics of a resistive SFCL with 16 ${\Omega}$ of resistance for a single line-to-ground fault in the 22.9 kV system. The transient current during the fault increased up to 6.33 kA, 5.80 kA and 3.71 kA without SFCL at the fault angles of 0${\circ}$,45${\circ}$ and 90${\circ}$, respectively. An resistive SFCL limited the fault current to 2.27 kA in a half cycle. The quench resistance of 16 ${\Omega}$ was suggested to be appropriate to limit the fault current in the 22.9 kV distribution system.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.928-933
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• 1998

This paper presents a novel current control system to eliminate the steady state control error and to improve the transient characteristics for PWM AC-DC converter. A general mathematical model of the converter that is represented as a state-space model is first established. The state-space model is used for the simulation of PWM switching converter with the proposed current control system. The proposed sinusoidal tracking control system that does not require coordinate transformations using principle of the integral controller is described. It is proved that the steady state deviation reduces to zero through a transfer function of source current control system. Finally, it is seen that simulations agree with the experimental results in source current and reference of controlled ac current loop.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.227-232
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• 1999

The stability of Power system installed Hi-Tc Superconducting Fault Current Limiter(SFCL) is analyzed as a process of developing SFCL. For investigation, a simple mimic system(only one generator) is assumed and then the circuit with SFCL in that system is solved for transient performance. In case the SFCL is installed in the power system, it protected synchronization more effectively both in symmetrical 3-phase fault and single phase line to ground fault in that the machine remains in synchronism for the more time than of without superconducting fault current limiter. It shows that the superconducting fault current limiter not only limits fault current but also protest synchronism. So for design of this SFCL, its synchronism protection property must be considered.