• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1903-1905
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• 2002

The degree of contamination on outdoor insulator is one of the most important factors for the determination of insulation level. And the salt, NaCl, is known as the most dangerous contaminants in the most region of the world. As shown through the preceding study, we could find the close relationship between the generation and deposition of salt contaminants and the meteorological conditions. To analyze the relationship, we monthly measured the ESDD for some sites with brush wiping method, and daily measured the density for one site with the automatic measuring apparatus. And, with the measured data and the meteorological data from KMA(Korea Meteorological Administration), we analyzed the relationship between the two factors with regression method. Through the results of this investigation, we could quantify the comparative contribution of the climatic factors for the pollution level of outdoor insulator, and the results could be used as a useful reference for the maintenance of overhead lines and substations.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.20-29
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• 2011

There are a lot of electrical and electronic components and pneumatic parts sensitive to vibration and shock in the VEB assembly which KARI directly transports among the KSLV-I upper stage transportation items. So, the special attention in the transportation is required. The transportation container with the apparatus for controlling environment was made in order to meet the requirements. The transportation tests using the engineering model were performed 4 times to verify the performance of the transportation container and to conform the transportation conditions(transportation velocity, route, etc.). In this document, the previous transportation history of the VEB assembly, the overview and the result of the KSLV-I FM unit 2 VEB assembly transportation are described.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.73-80
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• 1998

This Study was performed to get the suitable oil dispersion agent by assessment of color strength of organic pigment in non-aqueous systems. Organic pigment is used as a color expression material with other body pigments in the make-up products. But occasionally aggregation or agglomeration occurs for the lack of affinity with medium, This function is the cause of disturbing homogeneous dispersion, and then bring about an instability of products. Our study, research of dispersion mechanism between the pigment and oil phase, has been executed to solve this problem, and find a oil dispersion agent having optimum dispersion condition. Generally dispersion is related to between the solid-liquid mutual properties and electrical phenomena associated with solid-liquid interface. This factor is determined to input energy, milling time, optical properties, particle size, rheological properties, etc. Ideal dispersion state is told that coloring primary solid particle is homogeneously dispersed in medium. Good dispersed colorants are strongly and clearly appeared. We are already known that the particle size of organic pigment, chemical properties and viscosity of medium, refractive index. Consequently We determine the affinity of medium and organic pigment by measuring of color strength in the same mechanical condition. UV-VISIBLE RECORDING SPECTRO PHOTOMETER is used for measuring apparatus. We can decided the dispersion level of oil dispersion agent by measuring absorbance of color strength in the visible range that diluted medium for colloid colorant particles.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1574-1576
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• 1994

$SF_6$ gas has become an important insulation medium in modern electric power apparatus, because of its high insulation withstand levels and good arc quenching capability. For the application of $SF_6$ gas in GIS the estimation of insulation properties is a fundamental point. Moreover the reduction of withstand levels in case of inhomogeneous fields caused by particles or fixed protrusions is of special interest. It is known that the presence of free conducting particles in GIS can significantly lower the insulating level of $SF_6$ gas at elevated pressure and also it has been recently shown that dielectric strength is greatly reduced by fast transients such as disconnector surges where metallic particles are involved. In this paper, we have disigned the particle test chamber rated 362kV for the purpose of investigating the discharge characteristics in SF6 gas where inhomogenius fields are caused by metallic particles.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1853-1855
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• 2000

An experimental investigation has been performed in order to understand the $\Phi$-q-n characteristics related to the PD taking place from the various size of artificial defects inserted in epoxy insulation. In this purpose, PD has been detected simultaneously by two different methods such as commercialized PD detector(TE571) and our detection system using self designed CT type sensor. Under the presence of void in epoxy insulation, PD has been initiated at the voltages between 16kV and 20kV which are much lower than the dielectric strength of epoxy insulation (130kV/mm$\sim$l50kV/mm). And also it is revealed that $\Phi$-q-n characteristics have been observed to be dependent upon the size of the artificial defects. Throughout this work, the on site applicability of the self designed Sensor has also been proved by comparing the results with those from the commercialized PD detector. And more one, considerable basic data regarding the insulation, diagnosis could be provided to understand the presence of the voids possibly inserted into the epoxy insulation system of the power apparatus.

• 전기의세계
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• v.26 no.4
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• pp.41-53
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• 1977

With the equivalent series circuit analyzed aby revolving field theory and drawn by using the equivalent circuit constant ratios in capacitor motor with windings not in quadrature having space harmonics in its magnetic field (the above ratios are the equivalent circuit constants for the fundamental flux to the magnetizing reactance of the circuit), the equation for the alternating torque with twice line freequency in the motor is directly derived, and the alternating torque is measured with the self-made stator vibration angle amplitude measuring apparatus that is composed of a pickup, filter, photoelectric pickoff etc. The measured values satisfactorily compared with computed values. The properties of the alternating torque characteristics for respective harmonic fluxes and the r5esultant alternating torque characteristic, the effects of the alternating torque characteristics for respective harmonic fluxes on the resultant alternating torque characteristic, the effects of the variation in the motor constants and the equivalent circuit constant ratios for the fundamental flux on the alternating torque characteristics for respective harmonic fluxes and the resultant alternating torque characteristic, are made clear, applying the equation. There exist the optimum values of the motor constants and the equivalent circuit constant ratios for the fundamental flux for decreasing the alternating torque, and the value could be determined in design by the method presented in this paper.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2060-2062
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• 2005

Partial Discharge (PD) phenomena occurred by different nature of insulating defects has been regarded as a random process by which Phase Resolved Partial Discharge Analysis (PRPDA) has been proposed and then commercially accepted for the diagnosis of the power apparatus since more than three decades. Moreover, for the same purpose, a novel approach based on the Chaotic Analysis(CAPD) has been proposed since 2000, in which PD phenomena is suggested to be considered as a deterministic dynamical process. In this work for the diagnosis of GITr, four different types of specimen were fabricated as a model of the possible defects that might possibly cause its sudden failures such as turn to turn insulation, inter coil insulation, free moving particle and protrusion. For this purpose, these defects are introduced into the GITr mock-up and experimental investigations have been carried out in order to analyze the related PD patterns by means of both PRPDA and CAPD respectively and then their comparisons are made systematically.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.696-698
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• 2007

As overhead transmission lines are exposed to the outdoor weather, lightning induced fault accounts for about 66% of faults in transmission lines. The lightning may cause the damage of power system apparatus or the shut down of electricity. Not only in order to decrease the damage of the power system itself but also to ensure the reliable power supply, an appropriate insulation design based on the long-term lightning statistics is required. Meanwhile, real time information of lightning might be more useful to quickly locate the point of lightning induced fault in the line, leading to minimization of the adverse effects derived from the fault. Korea Electric Power Corporation has been providing an on-line lightning information service, named as KLDNet, since 2006 in order to meet the need inside our company. This paper describes the development and application of the information system.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.19-21
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• 2002

Recently, it has become more competitive to take larger market share among domestic companies manufacturing high-power apparatus. Unfortunately, the size of total market in this field is being smaller than before because the business of transmission and distribution of electric power is being shifted from government control to private management. To save this situation, we are trying to develop new high-voltage Gas Insulated Switchgear for export such as 245kV GIS and 300kV GIS. It is very important to make GIS compact size to have international competitiveness against European companies. By reducing GIS's dimensions same as 170kV class, we expect to launch abroad successfully. Many factors should be considered to achieve good performance during short-circuit making-breaking. Analysis on cold gas flow is one method widely used to evaluate small-current interruption. Through this analysis, we can examine the dielectric characteristics at the weak points in the circuit-breaker. In this paper, we describe the results of cold-gas flow analyses on 245kV and 300kV circuit-breakers.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.173-175
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• 2002

In general, CT and Shunt have been traditionally used as a sensor for detecting the partial discharges in order to diagnose the present insulation state of the electric power apparatus. The former is very convenient for the practical application since it is not only non-contact method but its frequency bandwidth and resonance frequency could be designed for its specific application. However, it has been proved to have poor linearity and low sensitivity. For the latter, even though it is an ideal sensor, noise from the power source and the ground could flow into the system. Furthermore, the surge current could be easily come into the measuring systems giving rise to a severe breakdown. In this respect, a hybrid sensor has been designed and fabricated in order to overcome the shortcoming of these two types of sensors. For this purpose, the experimental comparison with commercialized products has been also carried out. In this concept of the hybrid sensor, two different impedances could provide the passage of the signals. In this way, the discrimination of the noise could be accomplished very effectively with high ratio of signal over noise(S/N) under the little influence from the external noises and the breakdown.