• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1863-1865
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• 2004

As rise the demands for the protcetion of environment and the compactness of equipments, the movement brisks for replacing the circuit breaker of GIS(Gas Insulated Switchgear) to VI(Vacuum Interrupter). For these reason an increase in the interruption capability of VI is required. To satisfy these requirement, the academic and industrial worlds have been studying extensively for AMF(Axial Magnetic Field) contact, which is effective in interrupting large current over tens of kA, and introduced many kind of AMF contacts. However there are little effort to compare these contacts comprehensively, so it is difficult to choose most suitable shape for user's needs. In this paper, focusing unipolar type contact among various type of AMF contacts, we performed magnetic field analysis for several models designed in same dimension and compared the result and characteristics of each model in order to help deciding the direction for developing profitable VIs for interrupting large current.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.479-482
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• 2008

In order to more closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, the thermal-fluid characteristics of high current vacuum arcs were calculated by a commercial multiphysics package, ANSYS, in order to obtain Joule heat, Lorentz force and the interactions with flow variables. We assumed the diffused-mode arc within an AMF vacuum interrupter. It was found with four different currents that the temperature distributions on the anode surface are diffused uniformly without concentration in 7kA for both types (cup and coil-type). But the arc plasma transition and an increase of thermal flux density for increasing the applied current have caused the change of temperature distributions on the anode surface. We should need further studies on the two-way coupling method and radiation model for arc plasmas in order to accomplish the advanced analysis method for multiphysics.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1559-1561
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• 1994

At present, the principle of puffer action in high current interruption is adopted in almost of the EHV(Extra High Voltage) and UHV(Ultra High Voltage) GCB(Gas Circuit Breakers). The thermal interruption capability of these GCBs critically depends on the pressure rise in the puffer cylinder at current zero. The pressure rise in the puffer cylinder depends on the puffer cylinder volume, flow passage and leakage area in the interrupter, stroke curve etc. Recently commercial CFD(Computational Fluid Dynamics ) packages have been widely adopted to calculate the pressure distribution in the interrupter. However, there are still several problems with it, e.g. very expensive price, moving boundary problem, computation time, difficulty in using the package etc. Thus, the calculation of the puffer cylinder pressure in simple and relatively correct method is essential in early stage of GCB design. In these paper, the model ing technique and computed results for EHV class GCB (HICO, 145kV 40kA and 362kV 40kA GCB) are presented and compared with available measured results.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1593-1598
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• 1994

Recently rotary-arc, thermal expansion and their composite interrupters are widely used in the distribution power system because they have lots of advantages in making the larger interrupting capacity, the smaller size, the lighter weight and the less surge. A model interrupter of rotary-arc type, which has constant stroke and thermal expansion volume, was studied by varying the design parameters, i.e. the number of turns of the driving coil, the inner diameter of the moving contact, the gas pressure and the shape of the fixed contact for this project. Short cicuit current interrupting tests were conducted to the model interrupters by varying the requirements from 42% to 175% of the test voltage, interrupting current and transient recovery voltage for the test duty No.4 of 7.2kV 12.5kA single phase test. The pressure rise, minimum and maximum arcing times were analyzed for each model interrupter. All types of model interrupters showed good interrupting performances and sufficient design margins for the ratings.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.161-165
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• 2004

In this paper, we have designed the ground faults detection and interrupting controller at normal condition of AC 120v to 240v rating voltage. Ground faults in electrical network have the characteristics of low current, 60㎐ frequency to 2㎑frequency. The load condition are no load and 20A load. The trip level of the controller is 6㎃ with ground faults. The Controller algorithm is implemented using pic16c71 microprocessor.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.627-630
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• 1993

The arc characteristics have influences on the current interruption phenomena in the regimes of low current as well as high current. It is very important to understand the arc characteristics for the initial design of a circuit breaker. This article describes the theoretical analysis of the arc characteristics by means of arc energy integral method when convection dominated low current arcs are produced in the dual-nozzle air and $SF_6$ gas flows of a model interrupter. The arc radius, average electric field strength and arc voltage have been investigated at the current range of 60 to 230 A and at the upstream pressure of 0.6 MPa in both air and SF6 gas. The results have been compared to show the difference of both gases and the trends similar to those of other investigations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.184-190
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• 2009

One of the purposes of arc control is to change its state to the diffuse state before current zero as soon as possible. This can provide optimal conditions for full extinction of arc by minimizing the quantity of residual plasma between contacts near current zero. TRV(transient recovery voltage) occurs at current zero at the same time with current interruption. If there is substantial residual plasma near current zero it can cause 'post arc current' by the interaction of its conductance with TRV. In this paper, arc control ability as a function of configuration of spiral type VI contacts was compared on the criteria of the time taken for arc to reach to the diffuse state.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.876-880
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• 2013

The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The principal factor of the fire is electric arc or spark accompanied with such electric faults. Earth Leakage Circuit Breaker (ELB) and Molded_case Circuit Breaker (MCCB), that is, Residual Current Protective Devices (RCDs) used on low voltage distribution lines cut off earth leakage and overload, but the RCD can not cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied in low voltage distribution panel are prescribed to rated breaking time about 30[ms] (KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To improve such problems, this paper studies on an arc fault circuit interrupter (AFCI) using the distorted voltage wave in electric arc faults. The proposed voltage sensing type AFCI is an electrical fire prevention apparatus of new conception that operates a circuit breaker with sensing the instantaneous voltage drop of line voltage at electrical faults occurrence. The proposed AFCI is composed of control circuit topology using some semiconductor switching devices. Some experimental tests of the proposed AFCI confirm practicality and the validity of the analytical results.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.372-375
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• 1999

This paper presents an arc(hot-gas flow field) analysis method in GCB. This method includes the Lorentz's force due to magnetic field, turbulent viscous effect and radiation heat transfer which are indispensable to the analysis of hot-gas flow. To verify the applicability of the Proposed method, steady state hot-Eas flow analysis within a simplified interrupter has been carried out. Inlet boundary pressure values were assumed to be 9.0atm and 12.0atm. For each inlet boundary condition, three cases of hot-gas flow field analyses were performed according to the values of arc currents which were assumed to be D.C 0.6kA. 1.0kA and 2.0kA. The results revealed that the arc radius at nozzle throat has been concentrated by increasing the pressure of nozzle upstream and that the maximum temperature of arc core has been decreased along to nozzle exit and the high temperature lesion come to be wide in nozzle downstream. From these results, it is confirmed that the proposed method will be applicable to predict the large current interruption capability of GCB.