• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.82-87
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• 2013

Electrical leakage happens when faults in electrical apparatus or power lines occur. It causes electrical fires and electric shocks. In order to reduce accidents caused by electrical leakage current, it is important to detect faults effectively and shut off the power. In this paper, firstly we analyzed statistics of electrical fires and electric shocks caused by electrical leakage current. Secondly, standards of allowable leakage current and body impedance models were analyzed. Lastly, effective application methods for breaking electrical leakage current were suggested. The results will provide useful preventive measures of electrical fires and electric shocks caused by electrical leakage.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1782-1784
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• 2003

This paper evaluates the uncertainty to measurement of the power of measuring system used in the performance evaluation of electrical apparatus and introduces the reduction method of the uncertainty.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1299-1303
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• 1995

The detection and measurement of partial discharge activity prevalent in the solid insulating systems of high-voltage generator stator windings has, for many years, been a recognized method of assessing the insulation condition of such systems. Partial discharge activity occurs at sites of degradation within, or at the surface of, stator's insulation systems under high voltage stressing. However, partial discharge pulses suffer from attenuation and distortion when transmitted along windings, because of the complex L-C network between windings. The mode of transmission varies with the signal frequency and is dependant on the geometrical configurations of windings. This paper reports the investigated results of the signal propagation characteristics along the windings when both sinusoidal signals and simulated partial discharge pulses are injected at the various positions of stator windings within the 25 MVA, 11 kV hydro generator. The on-line identification technique of partial discharge location in generator windings is also proposed in this study.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.755-756
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• 2006

This paper presents the temperature distribution of the oil-immersed self-cooled transformer with radiator performed by coupled magneto-fluid-thermal analysis. Particularly, 3D temperature distribution of cooling oil and sub-components under the natural convection is obtained by computational fluid dynamics analysis, while heat sources are predetermined by magnetic field analysis using F.E.M. The predicted temperature distribution of the power transformer model is compared with the measured data for verifying the validity of the proposed analysis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.894-895
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• 2007

This paper presents coupled analysis between finite element method and analytic technique for predicting temperature rise of 25.8kV 25kA three-phase GIS bus bar. The power losses and temperature distribution of three-phase GIS bus bar model are analyzed by magneto-thermal finite element method. The heat transfer coefficients on the boundaries are analytically calculated by applying Nusselt number considering material constant and model geometry for the natural convection. And these are used as the input data to predict the temperature rise of three-phase GIS bus bar model by coupled magneto-thermal F.E.A. The predicted temperature of 25.8kV 25kA three-phase GIS bus bar model shows good agreement with the experimental data.

• KIEE International Transactions on Power Engineering
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• v.3A no.3
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• pp.139-147
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• 2003

The paper presents a novel approach of constructing the state matrix of the multi-machine power system for SSR (subsynchronous resonance) analysis using the linearized equations of individual devices including electrical transmission network dynamics. The machine models in the local d-q reference frame are integrated with the network models in the common R-I reference frame by simply transforming their output equations into the R-I frame where the transformed output is used as the input to the network dynamics or vice versa. The salient feature of the formulation is that it allows for modular construction of various component models without rearranging the overall state space formulation. This universal SSR small signal stability program provides a flexible tool for systematic analyses of SSR small-signal stability impacts of both conventional devices such as generation systems and novel devices such as power electronic apparatus and their controllers. The paper also presents its application results to IEEE benchmark models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.207-208
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• 2007

Epoxy resin insulators show a lot of advantages for electrical power apparatus. Because epoxy resin provide electrical and mechanical characteristic which is excellent, it is desirable to apply epoxy resin as a spacer and post insulation in Gas Insulated Switchgear (GIS). In this study, we have investigated the influence of surface electric field attached particle contaminated spacer surfaces under SF6 gas. Also, we performed analysis of electric field. As a result, when the particle was attached on spacer, we found out a surface electric field of characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.1-12
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• 2014

This paper is proposed to design the new heat-sink apparatus for improving the heat transfer characteristics in the power LED chip, and results of the operation characteristics were discussed. The core design is that the soldering through-hole on the FR-4 PCB board is formed to the effective heat transfer. That is directly filled with Ag-nano materials, which shows the high thermal conductivity. The heat transfer medium consisting of Ag-nano materials is classified into two structures. Mediums are called as the heat slug and the multi-pin in this work. The heat of the high temperature generated from the LED chip was directly transferred to the heat slug of the one large size. And the accumulated heat from the heat slug was quickly dissipated by the medium of the multi-pin, which is the same body with the heat slug. This multi-pin was designed for the multi-dissipation of heat by increasing the surface areas with a little pins. Subsequently, the speed of the heat transfer with this new heat-sink apparatus is three times faster than the conventional heat-sink. Therefore, the efficiency of the illuminating light will be improved by adapting this new heat-sink apparatus in the large area's LED.

• International Journal of Safety
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• v.4 no.2
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• pp.18-23
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• 2005

There are many electrical connections in the electric apparatus and most fires due to a fault contact result from a failure or misuse of electric apparatus and installation. The fault contact happens between electrical connections by the loose and the mechanical vibration. In this paper, we have investigated thermal and electrical properties of screwed electric contacts due to the mechanical vibration. The exciter was connected to a signal generator and power amplifier that provided the vibration frequency and amplitude. The vibration, temperature and voltage data were sent to a data acquisition system (DAQ). In the case that fault contact took place, the arc happened between the screwed electric contact and electric wire, heat due to the arc was transmitted to the adjacent insulators, for which the oxide could be generated more. In addition, a spark was generated and the insulator began to melt. Thus, the possibility of electrical fire became the highest in this case. Finally, when the fault contact takes place due to vibration, the hazard of an electric accident is very high.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.411-414
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• 1989

It is well known that switching overvoltages in the electric power system can damage electric power apparatus. To investigate switching overvoltages, electric power system has been modeled using mathematical equal ions. Using developed model, switching overvoltages in the transformer terminal have been computed and analysed.