• 한국초전도ㆍ저온공학회논문지
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• 제5권2호
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• pp.16-19
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• 2003

Quench and recovery process of high-temperature-superconductor (HTS) film deposited on the sapphire substrate is studied numerically. The quench is developed by fault current and the superconductivity is recovered by convection of heat into coolant. After the fault current. the HTS film experiences the quench state. current sharing state. and finally recovers the superconductivity. Numerical results of this study are compared to the previous experimental results. and shows that this numerical work can explain the mechanism of quench/recovery characteristics of HTS film.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.181-184
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• 2003

Quench and recovery process of high-temperature -superconductor (HTS) film deposited on the sapphire substrate is studied numerically. The quench is developed by fault current and the superconductivity is recovered by convection of heat into coolant. After the fault current, the HTS film experiences the quench state, current sharing state, and finally recovers the superconductivity. Numerical results of this study are compared to the previous experimental results, and shows that this numerical work can explain the mechanism of quench/recovery characteristics of HTS film.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권6호
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• pp.368-371
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• 2004

The quench current characteristics of the superconducting solenoids with large diameter were experimentally investigated. Three solenoids with inside diameter of 450mm were fabricated with different tensions and different types of epoxy applications. The quench current of each solenoid was measured according to the various ramping rates of current. The highest quench current was obtained in the solenoid impregnated with epoxy after winding with tension of 20 percents of the yield strength of the superconducting wire. It was found that the quench currents were almost independent of the ramp rate of current. From the results, although the training effect in the solenoid appeared with epoxy impregnation, the quench current of solenoid impregnated with epoxy was higher than that without epoxy impregnated The test results are presented and discussed.

• Progress in Superconductivity
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• 제3권2호
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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.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.337-342
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• 2000

We fabricated resistive superconducting fault current limiters based on YB $a_{2}$/C $u_{3}$/ $O_{7}$ thin films and investigated their quench propagation characteristics. The YB $a_{2}$/C $u_{3}$/ $O_{7}$ films was coated with a gold layer and patterned into 1 mm wide meander lines by photolithography. The quench was concluded to start locally and propagates until completed. The quench propagation characteristics were explained based on the heat transfer within the film as well as between the film and the surrounding liquid nitrogen. The quench completion time depended strongly on potential fault current amplitude and not significantly on fault angle which indicates that the quench propagation speed is affected more by heat dissipation rate than by fault current increase rate. The quench completion time was 1 msec at the fault current of 65 $A_{peak/{\ak}}$.

• 대한전기학회논문지:전력기술부문A
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• 제53권1호
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• pp.13-21
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• 2004

In the design of superconducting cable systems, quench analysis have to be advanced for applying to a real systems. It is necessary to calculate the current, voltage and resistance during the quench. Simulation program named EMTDC was used to analyze the quench state. Normal zone evaluation and quench development with EMTDC are one of the major features of quench analysis. This paper presents the two kinds of quench control models which are the Switch Control Type and the Fortran Control Type. In case of the quench developing area, the simplicity cable model consist of resistance, inductance and capacitance. The impedance of the pipe type superconducting cable is calculated by numerical analysis method. The resistance and inductance increased during quench. However the variation have an effect on the fault current. The voltage was also developed by resistance and inductance. This paper presents the relationship between the current. voltage, resistance and inductance during quench.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.889-894
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• 2007

We investigated the quench velocity of superconducting fault current limiter (SFCL) dependent on the source voltage. $YBa_2Cu_3O_7$ (YBCO) thin film was used as the current limiting element for SFCL. The analysis on the quench velocity of SFCL is essential to determine the capacity of circuit breaker (CB) or coordinate with CB. Generally, the quench velocity of SFCL is related with the short-circuit current. To change the short-circuit current, in this paper, the amplitude of the power source voltage is adjusted. Through the fault current limiting experiments, the quench velocity of SFCL was confirmed to increase fast as the source voltage increased. On the other hand, the peak limited current was shown to increase with steady rate of increase.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.272-275
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• 2003

Quench and recovery process of high-temperature-superconductor(HTS) film deposited on the sapphire substrate is studied numerically. The quench is developed by fault current and the superconductivity is recovered by convection of heat into coolant. After the fault current, the HTS film experiences the quench state, current sharing state, and finally recovers the superconductivity. Numerical results of this study are compared to the previous experimental results, and shows that this numerical work can explain the mechanism of quench/recovery characteristics of HTS film.

• Progress in Superconductivity
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• 제3권2호
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• pp.224-228
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• 2002

We investigated the quench properties of superconducting fault current limiters (SFCLs) connected in parallel. It was carried out as an effort to scale up the current capacity of SFCL toys texts. SFCLs were based on $YBa_2$$Cu_3$$O_{7}$ films coated in-situ with a gold layer and fabricated by patterning the films into 2 mm wide and 42 cm long meander lines by photolithography. Two SFCLS were connected in parallel and tested with simulated AC fault currents. Initially the current was divided unequally into branches of parallel connection due to unequal resistance of the branches. However, once quench started in the SFCLs, the current oscillated between the branches and then was distributed nearly equally between the branches. In other words, the elements quenched simultaneously. The oscillation amplitude decreased as the source voltage was increased: the oscillation was the most prominent near the quench current. The observed oscillation and the consequent simultaneous quench was understood in terms of quench start and development in the SFCLs.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권9호
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• pp.584-589
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• 2000

We fabricated resistive superconducting fault current limiters (SFCL) based on YBCO thin films grown on a 2-inch diameter Al2O3 substrate. The current limiting element was 1 mm wide and 260mm long meander line prepared by standard photolithography. The minimum quench current of the current limiting element was about 8 Apeak. This SFCL sucessfully controlled the fault current below 14.3 Apeak at the voltage of 100 Apeak which is otherwise to increase up to 141 Apeak. The quench completion time was less than 3 msec. The temperature of the current limiting element rose to about 200 K in 3 cycles after fault. The SFCL showed reproducible quench during hundreds times of repeated experiments.