• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.233-241
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• 2005

The present model of a SF6 arc accounts for the copper vapour contamination from the electrodes inside a Laval nozzle of a circuit breaker. Steady state simulations have been done for the arc with electrode gap of 60mm and DC electric current of 500A, 1000A and 1500A for both cases with and without copper contamination. The effects of electrode polarity are considered for the arc current of 1000A. It was found out that evaporation of copper from the anode results in a cooling of the arc in a region close to the electrodes. The electrical potential across the electrodes is not sensitive to the presence of copper vapour, typically less than $4\%$ difference. Transient analysis has been done in order to obtain the arc properties at current zero. The arc current is increased linearly from -1000 to 0A when the upstream electrode is cathode with constant dI/dt of $27.0A/{\mu}s$ (or decreased linearly from 1000 to 0A when upstream electrode is anode). It has been predicted that the presence of copper vapour reduces the interruption capability of the breaker.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.59-65
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• 2007

In this study, 6-DOF simulator using pneumatic cylinder driving apparatus was manufactured because a pneumatic cylinder driving apparatus is superior to electric driving motor and hydraulic actuator, which used in traditional 6-DOF simulator, in competitive price and acceleration performance, and, 6-DOF motion can be realized at a low price in case that relatively low load is imposed on the simulator. The possible range of pose control of the simulator was investigated by inverse kinematics, and, it was controlled by a linear controller derived from linear model of the simulator. The Experimental results show that the simulator follows given coordinate well.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.98-102
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• 2007

In this study, a measurement method of leakage flow-rate for pneumatic driving apparatus is proposed. The existing measurement methods of leakage flow-rate of air need disassemble the test component. Therefore, there is no effective method to measure the leakage flow-rate while operating pneumatic driving apparatus. In this study, the leakage flow-rate is measured from the pressure change in an isothermal chamber that can realize isothermal conditions by stuffing the steel wool into it. Therefore, a wide range of flow-rate could be measured only from the pressure response and the leakage flow-rate can be measured during operating pneumatic driving apparatus. The effectiveness of the proposed method is proved by experimental results.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.1
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• pp.15-19
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• 2006

In this study, a measurement method of leakage flow-rate for pneumatic driving apparatus is proposed. The existing measurement methods of leakage flow-rate of air need disassemble the test component. Therefore, there is no effective method to measure the leakage flow-rate while operating pneumatic driving apparatus. In this study, the leakage flow-rate is measure from the pressure change in an isothermal chamber that can realize isothermal conditions by stuffing steel wool into it. Therefore, wide range of flow-rate could be measured only from the pressure response and the leakage flow-rate can be measured during operating pneumatic driving apparatus. The effectiveness of the proposed method is proved by experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.23-28
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• 2000

Insulator systems using resin casting apparatus are useful to realize the high capacity, small size, and combined electric power equipments, and are expected to bring various advantages. In Korea, epoxy resin molded apparatus have been restricted to indoor uses till now. On the other hand, in Europe, molded insulators and transformers and so forth have been practically used since the former half of 1960's. Recently, investigation on epoxy resin materials and molded apparatus for outdoor use have ben intensively carried out. Probably, this is because electric power outdoor apparatus such as distribution transformer can be given multi-functions by using outdoor epoxy resin compound This study describes the trend on the development of epoxy mold transformers, and important technologies applied for outdoor use.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.43-48
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• 2001

In conventional wind generation systems, since the blade rotates at low speed when the velocity of wind decreases their operations are possible only under limited conditions. Therefore they are in trouble of self-generation without the help of auxiliary generation devices outside. In addition, most of them have very low usage efficiency because of the characteristic changes of wind. For the solution of these problems and for enough generation regardless of districts and geographical features the rotation energy stored in a spring drives a compact generator and then electric power is stored at battery and supplied to the load continuously according to the lack of wind force. In this paper, the fabricated system consisting of a wind generator and power storage apparatus was introduced and its operation characteristics were analyzed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.4
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• pp.129-136
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• 2001

In order to evaluate the dielectric recovery strength for GCBs, two equations have been usually utilized. One is the empirical formula obtained from a series of tests and the other is the theoretical formula obtained from the streamer theory. In this paper, both methods were applied to predict the small capacitive current interruption capability of model circuit breakers and were investigated in terms of the reliability by comparing the simulation results with test ones.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.4
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• pp.180-183
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• 2004

This paper presents a description of the point collocation method and its application to the electromagnetic field computation. The interpolation scheme is based on the fast moving least square reproducing kernel approximation. In the method, the integration cell is not required and the essential boundary conditions can be enforced directly. Numerical simulations on 1-D and 2-D problems are carried out to validate the method. It is found that computational efficiency is higher than the general mesh-free methods.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.193-195
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• 1996

In amorphous transformer core, magnetic field annealing is required for inducing uniaxial magnetic anisotropy to circular direction of the core. Generally annealing temperature is about foot, so insulator using in solenoid bed must have a high temperature stability, mechanical strength and good machinability. In this study, we made the magnetic field annealing apparatus using insulators, conductors, connectors and power supply. And then tested the apparatus in annealing process of 50 kVA amorphous transformers.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.593-596
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• 1992

An evaluation method for the effective length of electromagnet - which bas U-shape in frontview and trapezoidal in side view - is presented. Using 2D FEM, 2 analysing models are introduced for calculating effective length of the magnet ; the front model is using the normalized equi-pole face area of the magnet and the side model using the normalized equi-magnetic circuit. The ratio of the effective length to the length of bottom plate (core) comes out 1.25 - 1.30. In addition, 3D FEM analysis has been done and a proto-type test model is manufactured to verify the analysing method. The ratio by the experiment appears 1.2, which is reasonably in good agreement with the suggested numerical results.