• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.243-244
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• 2008

We experimentally investigated discharge phenomena inside vacuum interrupter at 1 to 20 Torr to simulate the vacuum leakage. We used glass type of vacuum interrupter where the internal pressure and the type of gasses can be varied according to requirement. The experiment is conducted under ac applied voltage and the experimental circuit is constructed to simulate the actual circuit used in cubical type insulated switchgear. We used two types of gases such as air and $SF_6$. The use of glass type vacuum interrupter allowed us to measure discharges occurring in vacuum interrupter optically. We measured and discussed the discharge occurring in both gases with a current transformer and ICCD camera. We a1so revealed that electromagnetic wave spectra emitted by the discharge have same frequency range for both gasses.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.49-55
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• 2003

This paper studied characteristics of surface discharge and tracking phenomena on the surface of solid insulators in Liquid Nitrogen(LN2) noticed as a cooling medium of high temperature superconductor. In order to investigate the bubble effect which have much influence on electric surface discharge in Liquid Nitrogen, knife type electrode and plane electrode were formed oppositely with A-mode, B-mode and C-mode configuration. It is considered that these result are fundamental data for electric insulation design of superconductor and cryogenic application machinery which will be studied and developed in the future.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.117-129
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• 2022

The downward discharge of the molten fuel to the lower structure of the fuel assembly could increase of the pressure drop and degrade of coolability of the assembly. To analyze the phenomena, experiments for the generation of the debris bed were conducted as LOF-DT series. Based on the debris bed in the LOF-DT, pressure drop experiment was conducted with intact and blocked component. Parametric study on the pressure drop was conducted by CFD. The LOF-DT experiments were conducted for the position and porosity of the debris bed. 85% of the debris were sedimented in the lower reflector, and 15% were in the nose piece, approximately. Porosity of the debris bed were about 0.7 and 0.85 in the lower reflector and nose piece, respectively. Pressure drop increased significantly with debris bed, especially in the lower reflector. More than 120 time of the pressure drop increased in the lower reflector, while only 10% increased in the nose piece. According to the parametric study, mass of the debris was the most important for pressure drop. The lower discharge phenomena could have a significant effect to the total pressure drop of the fuel assembly, approximately 10.8 times for the base case.

• 전기의세계
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• v.17 no.3
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• pp.39-42
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• 1968

We have been studying on the discharged phenomena if compound dielectrics for insulator which is very important in electric machinery and et al. In this paper we come to the couclusion that as a result of studying on the electric design of Ozonizer, the higher frequency becomes the better output could be got, and then discharge power could be the greatest by selecting the distance of the discharge gap and atomospheric pressure properly under the same applied voltage, and that power factor of the Ozonizer reached the maximum power at a particular frequency when the discharge power is maintained at constant.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.130-132
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• 2008

In the gas discharge lamp, starting procedure is composed of several physical discharge phases. The detailed phenomena are different according to lamp characteristics and ballasting method. This paper reviews starting methods in fluorescent lamp, and the starting procedure of HID lamp are investigated based on reviewed various waveforms.

• Journal of Environmental Science International
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• v.4 no.2
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• pp.169-180
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• 1995

This Daper presents effective simulation of the dispersion of thermal discharge which can be relesed at Boryong power plant. Applied numerical models are finite difference method for hydrodynamic analysis and Masch-model comprised of conditions for ambient current velocity. Application of these models is done in Cheonsu Bay Summing up the results of this study are as follows; 1. It is found that the result for measurements of temperature appears high at southwardly Songdo on flood. The reason is that tidal currents which flowed north direction were accompanied with southwardly dispersed thermal discharge. A minute Particle of thermal Plume has a tendency to dispels inward Deacheon Bay. 2. According to the results of numerical experiment, maximum distance for thermal discharge dispersion appeared 10.8 km at lower part and 8.6 km at upper part with power plant outlet as starting point. 3. Comparative the numerical simulation and Airbone Multispectral Scanner indicated that thermal discharge should be verified separative phenomena. The simulated results were compared with field data set showing good agreement. It is concluded that these model can be simulated well.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.100-107
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• 1999

The purpose of the study is to investigate the effect of H$_2$ pressure on partial discharge (PD) activity and aging rate in turbine generator winding insulations. A series of field tests and laboratory tests were peformed to investigate the effect of $H_2$ pressure on PD activity. Field tests were conducted at two unit turbine generators in two conditions, in $H_2$ pressure and in air atmosphere. Obtained results are as follows ; 1) ${\Delta}tan{\delta}$ and maximum partial discharge are reduced with increase of $H_2$ pressure and partial discharge inception voltage. 2) The reduction ratio of ${\Delta}tan{\delta}$ due to $H_2$ pressure is higher than one of PD magnitude. 3) Partial discharge pulses suffer from attenuation and distortion when transmitted along windings, because of the complex L-C network between windings. From the result, partial discharge pulses are subjected to resonance phenomena in a generator winding.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.271-273
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• 2007

This paper presents the experimental results of underwater discharges in 25 mm point-plane gap caused by impulse voltage. Discharge phenomena were observed by digital cameras and recorded by oscilloscope. As a result, discharge patterns in positive and negative polarity have different shapes according to applied voltage amplitudes. The positive discharge is like root but the negative discharge is similar to bush. As the voltage is increased, the discharge routs are thick and have more branches. Also the time to breakdown is inversely proportional to voltage.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.470-476
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• 1989

In order to develop a mathematical model which can predict the operating voltage and current of a discharge lamp, the properties and the physical phenomena of a low pressure gas discharge are investigated. Fluorescent lamp which uses a low pressure mercury-argon gas discharge is used in the model development. In a low pressure mercur-argon gas discharge, the continuity equation for each excited atom and electron, and the electron energy balance equation can predict the physical quantities of discharge. By coupling these equations and the circuit equation, the electrical characteristics of the discharge lamp can be predicted. To verify the validity of the suggested model, we calculated the voltage and current of a fluorescent lamp operating with inductor ballast for source frequency of 5KHz, 8KHz, 10KHz, and 13KHz. The results show good agreements in wave forms between the measured voltage and current, and the difference between the measured and calculated one is less than 5%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.75-81
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• 2000

This paper describes the partial discharge due to particles in $SF_6$ gas. A model GIS chamber was designed and manufactured. The partial discharge and breakdown phenomena due to the particles between electrodes were observed and partial discharge signals were detected, using an ultrasonic sensor. The analysis of the electric field by the states of the particle inserted between the electrodes, were also carried out. The partial discharge was observed at end while the particle was moving in $SF_6$ gas. The partial discharge in micro-gap grows to arc, and after all, it can cause a breakdown.The electric field strength was the highest in case that the particle was vertically attached on the conductor, and the lowest in case that it was horizontally attached on the enclosure.