• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1536-1537
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• 2011

The high-voltage circuit breaker plays an important role in the electrical system because there has been a need for suitable switching devices capable of initiating and interrupting the flow of the electric fault current. It continues as the contacts recede from each other and as the newly created gap is bridged by a plasma. The arc plasma happens inside the insulation nozzle of SF6 self-blast interrupter which is newly developed as the next-generation switching principle. The ablation of PTFE nozzle is caused by this high temperature medium, the PTFE vapor from the nozzle surfaces flows toward the outlets and the pressure chamber. The vapor makes the pressure of the chamber increased by heat and mass transfer from the arcing zone. Because the rate of ablation depends on the magnitude of applied current, it decreases when the current goes to zero. The compressed gas inside the chamber flows reversely toward the arc plasma during this moment. According to this principle, the arc can be cooled down and the fault current can be interrupted successfully. In this study, we calculate arc plasmas and thermal-flow characteristics caused by fault current interruption inside a SF6 self-blast interrupter, and to investigate the effect of PTFE ablation on the whole arcing history.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.800-802
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• 1997

After flashover occurs on the overhead distribution line by lighting strokes(direct or induced), the power frequency arc current continues. If lightning flashover occurs on the overhead lines using covered conductors, the power frequency art current with fixed path overheats the conductor, and arc fusion fault can be occurred. There are two categories protecting or reducing methods of arc fusion faults caused by lightning stokes. - Reducing lightning flashover rate : G/W, LA, etc. - Protection by AFPD(Arc Fusion Protection Device) : power follow current interruption. This paper presents lightning surge phenomena on overhead distribution lines and protecting performance of arc fusion Protection devices to the lightning strokes nearby overhead line.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.36-38
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• 2004

In many countries, including Korea, in order to transmit the more electric power, the higher transmission line voltage is inevitable. So, a rapid reclosing scheme is important for UHV transmission lines to ensure requirements for high reliability of main lines. But, because of the high voltage and long span of UHV lines, the secondary arc current flows across the fault point even after the interruption of the fault current. i.e. A critical aspect of reclosing operation is the extinction of the secondary arc since it must extinguish before successful reclosure can occur. In Korea transmission lines, it is scheduled to energize 765kV single transmission line(79km) between Sin-Ansung S/S and Sin-Gapyeong S/S at June 2006. Therefore this paper analyzes characteristics of the secondary arc extinction on 765kV single transmission line using EMTP. Simulation results shows that the average value of the secondary arc is $30A_{rms}$ and the auto-extinction time of it is longer at closer point to Sin-Gapyeong S/S.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.365-368
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• 2002

The design of industrial arc plasma systems is still largely based on trial and error although the situation is rapidly improving because of the available computational power at a cost which is still fast coming down. The desire to predict the behavior of arc plasma system, thus reducing the development cost, has been the motivation of arc research. To interrupt fault current, the most enormous duty of a circuit breaker, is achieved by separating two contacts in a interruption medium, $SF_{6}$ gas or air etc., and arc plasma is inevitably established between the contacts. The arc must be controlled and interrupted at an appropriate current zero. In order to analyze arc behavior in $SF_{6}$ gas circuit breakers, a numerical calculation method combined with flow field and electromagnetic field has been developed. The method has been applied to model arc generated in the Aachen nozzle and compared the results with the experimental results. Next, we have simulated the unsteady flow characteristics to be induced by arcing of AC cycle, and conformed that the method can predict arc behavior in account of thermal transport to $SF_{6}$ gas around the arc, such as increase of arc voltage near current zero and dependency of arc radius on arc current to maintain constant arc current density.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1540-1541
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• 2006

For limitation and interruption of short circuit currents from low voltage to extra high voltage applications, the electrical equipment including fuses and circuit breakers, are widely used today. But in order to anticipate increasing needs for effective and competitive device for limiting the growing fault current in electrical power systems, fault current limitation technologies and fault current limitation devices are widely introduced and investigated in these days. Fault current limiters are emerging electric equipment which is under development using various methods including superconducting fault current limiter, solid state fault current limiter, arc driving fault current limiters. And these various methods have some advantages and disadvantages to take into considerations In order to commercialize fault current limiters in the electrical networks, a lot of discussions should be given on the point that fault current limiting methods, need for fault current limiters, coordination with existing protective system, and field experience before commercialization. In this paper, recent trends of fault current limiting technologies will be reviewed and the key issues of superconducting fault current limiters will be dealt with. And finally, future applications of superconducting fault current limiters would be discussed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.12-18
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• 2007

As an arc fault interrupter, the AFCI mentioned in this paper has been designed to detect and interrupt arc faults due to wire deterioration, insulation, wire damage, loose connection, and excessive mechanical damage. Since AFCI is digital and uses mechanical and electric stress, the length of interruption against overload and over-current is much shorter than the current bi-metal method. Therefore, the risk of electrical fires has been reduced.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.4
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• pp.165-172
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• 2003

Low voltage circuit breakers are widely used in power distribution systems to interrupt fault current rapidly and to assure the reliability of the power supply. This paper is focused on understanding the interrupting capability, more specifically of the contacts and the arc runner, based on the shape of the contact system in the current molded case circuit breaker (hereafter MCCB). Moreover, in order to improve the interrupting capability of the circuit breaker, the estimation and analysis of the interrupting capability, based on the 3-D magnetic flux analysis, were developed. Furthermore, this paper also presents results of the estimation and analysis of the interrupting capability when applied to different model breakers. In addition, this paper analyzes the efficiency of the interrupting tests by forming false current paths consisting of a three-division cascade arc runner in the contact system. With regards to the interrupting test, there is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by the current and flux density be present. Based on the results of this study, this paper presents both computational analysis and test results for the newly developed MCCB 460V/225A/50㎄ contact system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.190-195
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• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

• Journal of Power System Engineering
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• v.4 no.1
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• pp.45-50
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• 2000

Circuit breakers have traditionally employed mechanical methods to interrupt excessive currents. According to power semiconductor technology advances in power electronic device, some mechanical breakers are replaced with solid state equivalents. Advantages of the contactors using semiconductor devices include faster fault interrupting, fault current limiting, no arc to contain or extinguish and intelligent power control, and high reliability. This paper describes the design of a static $100{\pm}10%V$ and 0 to 50A DC self-protected contactor with 85A "magnetic tripping" and 100A interruption current at $2.2A/{\mu}s$ short circuit of load condition using a new power device the HARRIS MCT (600V-75A). The self-protection circuit of this system is designed by the classical ZnO varistor for energy absorption and turn-off snubber circuit ("C" or "RCD") of the MCT.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2109-2112
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• 2016

The rate of rise of the fault current in DC grids is very high compared to AC grids because of the low line impedance of DC lines. In AC grids the arc of the circuit breaker under current interruption is extinguished by the zero current crossing which is provided naturally by the system. In DC grids the zero current crossing must be provided by the circuit breaker itself. Unlike AC girds, the magnetic energy of DC grids is stored in the system inductance. The DC circuit breaker must dissipate the stored energy. In addition the DC breaker must withstand the residual overvoltage after the current interruption. The main contents of this paper are to ${\cdot}$ Explain the theoretical background for the design of DC circuit breaker. ${\cdot}$ Develop the simulation model in PSIM of the real scaled DC circuit breaker for 1,800V DC railway. ${\cdot}$ Suggest design guidelines for the DC circuit breaker based on the experimental work, simulations and design process.