• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.145-151
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• 2005

The synthetic breaking test method was developed to evaluate the breaking performance of ultra high-voltage circuit breaker and made up of two independent circuits; current source circuit and voltage source circuit. In application of this test method, it is necessary to extend the arc of the test breaker. So, the new re-ignition system using VTGS (Vacuum Triggered Gap-Switch) was constructed to improve the efficiency and reliability of this test. In this re-ignition system, VTGS operates in high vacuum state of $5{\time}10^{17}$torr and control system consists of the triggering device and the air M-G (Motor-Generator). This re-ignition system showed the operating characteristics, such as delay time ($t_d$) and jitter time ($t_j$ not exceeding 5us and 1us respectively, and had the operating voltage of $25\~150kVdc$ at the gap distance of 24mm.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.206-208
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• 2006

본 논문은 전력기기에서 문제가 되는 온도상승에 대응하여 제품 개발시 선행 해석을 통한 온도 안정성 확보와 제품 신뢰성 향상, 설계 기간 단축을 위한 방안에 대하여 서술하고 있다. 전력기기의 온도 상승을 예측하기 위한 방법으로 전자계 해석과 열유동 해석을 동시에 수행하는 연계 해석법을 제안하며, 이 해석법의 검증을 위해 기중 차단기의 통전시 온도 상승에 대한 해석을 수행하였고, 실험을 통해 이름 검증하였다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.3
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• pp.143-150
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• 2003

In this paper, we developed the window based monitoring system. This system offers the analysis of accidents in the power plants, the operating status of relays and the historical data with which the experts can offer the idea about the operation of the power system. And we can also monitor the status of the ACB and relay at a long distance by means of the function of communication in the digital protective relay itself. By means of the above functions, we developed the system, which is run after the diagnosis and maintenance of the electrical machines and an amount of data are realized by graphical method fitting the operating convenience of the users.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.357-359
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• 1999

It is necessary for the optimum design of switching devices to calculate repulsion forces acting on the closed electric contacts flowing over-current, e.g. inrush current and overload currents. In this paper, the forces generated by currents and flux densities at the contact point when circuit breakers are in closed position are obtained by using 3D finite element method. According to the analysis, the optimum configuration of wipe springs and arc extinguishing chambers are newly designed and consequently type tests show satisfactory results.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• 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.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.961-965
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• 1992

It is well-known that shock waves frequently occur inside the nozzle of the interrupter, and that they play important roles in the arc interruption. A model interrupter with two-dimensional dual-airflow nozzles was used for this experiment. The arc was ignited with 1.4 mil copper wire stretched between the electrodes which were spaced out 56 mm. The arc current of 60 to 230 A was achieved by adjusting the external resistance from 5.5 to 1.6 ohms. The arc tests have been conducted for investigating the air arc characteristics, and the effects of shock waves and nozzle pressure ratios on the arc voltage, the arc resistance, the arc power, and average electric field. The results of these tests have been analyzed to provide insights into the arc characteristics for gas circuit breakers. The average electric field is represented by the function of the arc current to show the negative E-I characteristic explicitly. The effects of shock waves and nozzle pressure ratios are shown to be significant for a circuit breaker performance.

• 전기의세계
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• v.24 no.6
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• pp.77-84
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• 1975

This paper treats A.C. arc movement in a transverse A.C. magnetic field at atmospheric pressure with the purpose of selecting electrode materials and obtaining detailed data for design of A.C. air circuit breaker, plasma accelerator and plasma jet. Arc velocities in transverse magnetic field are measured by varying arc current, arc voltage, gap length, magnetic flux density and the erosion of electrode surface, which influence arc velocities. The main results are; 1)Arc velocities in transverse magnetic field have different values according to electrodes of various materials and decrease in a descending order of cold cathode, medium cathode and hot cathode. 2)Arc velocities in transverse magnetic field increases with arc current, arc voltage, gap length and magnetic flux densith and on the other hand decrease with the increase of electrode surface erosion. 3)D.C.arc velocity in D.C. magnetic field is higher than A.C. arc velocity in A.C. magnetic field of the same value.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2319-2321
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• 2003

본 연구에서는 전력계통에서 배전반 자동화 장치중 하나인 ACB(air circuit breaker) controller로 사용되는 OCR(Over Current Protection Relay)의 지능화와 성능개선을 모색하고자 한다. 개발된 이 장치는 전력계통에서 전류의 흐름을 지능화 알고리즘으로 감시하여 최적으로 사고를 방지할 수 있으며, 대화형의 다양한 기능과 통신기능을 내장하고 있어 원격제어 및 관리가 가능하는 특징을 포함한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1269-1275
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• 2015

Turbine-generator torsional response is caused by interaction between electrical transient air-gap torque and mechanical characteristics of turbine-generator shafts. There are various factors that affects torsional interaction such as fault, circuit breaker switching and generator mal-synchronizing, etc. Fortunately, we can easily simulate above torsional interaction phenomena by using ElectroMagnetic Transient Program (EMTP). However, conventional EMTP shows the incomplete response of super- synchronous torsional mode since it does not consider turbine blade section. Therefore, in this paper, we introduced mechanical-electrical analogy for detailed modeling of turbine-generator shaft system including low pressure turbine blade section. In addition, we derived the natural frequencies of modeled turbine-generator shaft system including turbine blade section and analyzed the characteristics of mechanical torque response at shaft coupling and turbine blade root area according to power system balanced/unbalanced faults.