• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1603-1605
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• 1994

Recently, Gas Circuit Breakers are rapidly replacing Vacuum Circuit Breakers in the medium voltage switchgear. This is due to the improved performance of - GCB in interrupting capability, price, weight, size etc., while the countermeasure to suppress the switching surges of VCB has not been satisfactory. Intensive research works on the GCB have been conducted in the world widely since 1980. Nowadays it is well known that the thermal expansion type GCB can provide- better performance than puffer type in the distribution power system. KERI has conducted researches in the GCB rated at 25.8kV 25kA with Jinkwang Co. using the thermal expantion principle since 1993. In this paper, the calculated results of electric and magnetic fields for the model GCB are presented and analyzed. The effect of permanent magnet used to improve the interruption capabilty at the low current level is also investigated. The design parameters for the interrupter inspected through the short-circuit tests conducted at high power laboratory of KERI.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2223-2225
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• 2005

In this work, experimental investigation has been mainly done. For this purpose, UHF sensor has been designed and fabricated to detect the partial discharges produced from the 10 artificial defects introduced into the real scale 70kV GIS mock-up under the high voltage at the well shielded room. And also, in order to verify the applicability of the proposed method at the site, the proposed CAPD (chaos analysis of partial discharge) is combined with spectral analysis method in order to identify the nature of the above 10 defects. The PD pattern recognition of each defect has been fulfilled by applying self developed artificial neural network soft ware. The result shows that the recognition rate is reached to be 80% by newly proposed method while the traditional PRPD analysis method leads us to obtain 41%. In consequence, it can be pointed out that the proposed method seems likely to be applicable to the real GIS at the site.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1330-1332
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• 2005

최근 세계시장이 Al-Casting 외함(알루미늄 주물탱크)을 적용한 GCB(Gas Circuit Breaker) 및 GIS(Gas Insulated Switchgear)를 선호하고 있으며, 이는 철재 외함에 비해 많은 이점을 갖고 있기 때문이다. 알루미늄 외함은 철재 용접형 제품에 비해 중량이 가벼워 취급 및 운반이 용이할 뿐 아니라 장기 사용 시에도 발청의 우려가 없으며, 2층 이상의 건물에 신설 또는 증설시 건물의 중량 제한에 따른 제약 조건에서 훨씬 자유롭다. 또한 Casting은 Welding형에 비해 분기부 전계 강도가 유리하고, 알루미늄은 철에 비해 열발생량이 적어 외함크기 축소가 가능하다. 또한 제작공정이 철재 용접외함에 비해 단순하고 대량생산에 유리하다. 이로 인해 외함이 표준화되고 GIS 모듈화가 완성되면 기종별 Series화하여 대량생산 체제 구축에 유리하게 된다. 점진적인 인건비 상승으로 용접형 외함의 단가상승이 예상되며, GCB의 경우 Al Casting형이 원가면에서도 유리하다. 이에 당사 GCB 및 GIS 제품 경쟁력 향상 및 수출시장 적극공략을 목적으로 현행 GCB 및 GIS 철재 용접형외함을 알루미늄 Casting 외함으로의 변경, 개발을 실시하였다. 본 연구에서는 Al Casting 외함을 개발하기 위한 일련의 과정에 대해 소개한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.831-836
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• 2015

This paper dealt with the PD (partial discharge) characteristics produced by metallic particles presented in a gas insulated switchgear. Four types of metallic particles such as a ball, a trapezoid, a rectangle, and a twist were fabricated and placed in a PD cell filled with $SF_6$ gas. PD pulses were detected through a $50{\Omega}$ non-inductive resistor. Calibration was carried out according to IEC 60270 and the sensitivity was calculated as 4 mV/pC. Apparent charge, pulse count, DIV (discharge inception voltage), DEV (discharge extinction voltage), and TRPD (time resolved partial discharge) were analyzed. Among the metallic particle types, the twist frequently occurred PD pulse at the lowest DIV, while the rectangle showed the highest. DEV of the twist was about 2 times lower than that for the rectangle. Kurtosis of ball clustered at high value, and skewness of other three metallic particles distributed at low value. TRPD showed different distribution by metallic particle types.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.114-119
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• 2008

With the improvement of industrial society, the high quality electrical energy, simplification of operation and maintenance, ensuring reliability are being required. We request urgently change a $SF_6$ for an environment friendly gas insulation material. In this paper the experiments of breakdown characteristics by pressure and gap change of Imitation-Air in model GIS(Gas Insulated Switchgear) were described. Also assess of breakdown characteristics about Imitation-Air and $SF_6$. It is considered in this paper that the results are fundamental data for electric insulation design of Distribution Power Facilities which will be studied and developed in the future. The pressure to be confronted to $SF_6$ gas 1[atm] for Distribution Power Facilities is Imitation-Air 3[atm]. And we could make an environment friendly gas insulation material with maintaining dielectric strength by Imitation-Air which generates a lower level of the global warming effect.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.781-789
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• 2016

Busbar has been used as electric conductor within extra high voltage (EHV) gas insulated switchgear (GIS), which makes EHV GIS higher security, smaller size and lower cost. However, the main fault of GIS is overheating of busbar connection parts, circuit breaker and isolating switch contact parts, which has been already restricting development of GIS to a large extent. In this study, a coupled magneto-flow-thermal analysis is used to investigate the thermal properties of GIS busbar in steady-state. A three-dimensional (3-D) finite element model (FEM) is built to calculate multiphysics fields including electromagnetic field, flow field and thermal field in steady-state. The influences of current on the magnetic flux density, flow velocity and heat distribution has been investigated. Temperature differences of inner wall and outer wall are investigated for busbar tank and conducting rod. Considering the end effect in the busbar, temperature rise difference is compared between end sections and the middle section. In order to obtain better heat dissipation effect, diameters of conductor and tank are optimized based on temperature rise simulation results. Temperature rise tests have been done to validate the 3-D simulation model, which is observed a good correlation with the simulation results. This study provides technical support for optimized structure of the EHV GIS busbar.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2545-2552
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• 2018

$SF_6$ has been widely used in high voltage power equipment, such as gas insulated switchgear (GIS) and gas insulated transmission line (GIL), because of its excellent insulation and arc extinguishing performance. However, $SF_6$ faces two environmental problems: greenhouse effect and high liquefaction temperature. Therefore, to find the $SF_6$ substitute gases has become a research hotspot in recent years. In this paper, the liquefaction characteristics of $SF_6$ substitute gases were studied. Peng-Robinson equation of state with the van der Waals mixing rule (PR-vdW model) was used to calculate the dew point temperature of the binary gas mixtures, with $SF_6$, $C_3F_8$, $c-C_4F_8$, $CF_3I$ or $C_4F_7N$ as the insulating gas and $N_2$ or $CO_2$ as the buffer gas. The sequence of the dew point temperatures of the binary gas mixtures under the same pressure and composition ratio was obtained. $SF_6/N_2$ < $SF_6/CO_2$ < $C_3F_8/N_2$ < $C_3F_8/CO_2$ < $CF_3I/N_2$ < $CF_3I/CO_2$ < $c-C_4F_8/N_2$ < $C_4F_7N/N_2$ < $c-C_4F_8/CO_2$ < $C_4F_7N/CO_2$. $SF_6/N_2$ gas mixture showed the best temperature adaptability and $C_4F_7N/CO_2$ gas mixture showed the worst temperature adaptability. Furthermore, the dew point temperatures of the $SF_6$ substitute gases at different pressures and the upper limits of the insulating gas mole fraction at $-30^{\circ}C$, $-20^{\circ}C$ and $-10^{\circ}C$ were obtained. The results would supply sufficient data support for GIS/GIL operators and researchers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.207-214
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• 2017

High voltage electric power transmitter GIS(Gas Insulated Switchgear) above 72.5kV needs to satisfy domestic Korean peninsular standard(ES-6110-0002) in KEPCO with respect to normal and special operation conditions which include internal gas pressure, dead weight, wind and seismic load. Some other requirements not described in Korean standard can be applied from other international standards such as IEC(International Electronical Committee) 62271-203 and 62271-207. The GIS is a kind of pressure vessel structure made of aluminum and filled with SF6 gas of internal pressure 0.4~0.5MPa. Finite element analysis of GIS is performed with such operational loads including seismic loading and the stability and reliability is determined according to ASME BPVC(Boiler and Pressure Vessel Code) SEC. VIII standard where the allowable stress level of the pressure vessel is suggested. The result shows that the stress of GIS is satisfied the allowable stress level and the safety factor is about 2.3 for Korean peninsular standard.

• Journal of Platform Technology
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• v.8 no.3
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• pp.10-21
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• 2020

Partial discharge occurs a lot in high-voltage power equipment such as switchgear, transformers, and switch gears. Partial discharge shortens the life of the insulator and causes insulation breakdown, resulting in large-scale damage such as a power outage. There are several types of partial discharge that occur inside the product and the surface. In this paper, we design a predictive model that can predict the pattern and probability of occurrence of partial discharge. In order to analyze the designed model, learning data for each type of partial discharge was collected through the UHF sensor by using a simulator that generates partial discharge. The predictive model designed in this paper was designed based on CNN during deep learning, and the model was verified through learning. To learn about the designed model, 5000 training data were created, and the form of training data was used as input data for the model by pre-processing the 3D raw data input from the UHF sensor as 2D data. As a result of the experiment, it was found that the accuracy of the model designed through learning has an accuracy of 0.9972. It was found that the accuracy of the proposed model was higher in the case of learning by making the data into a two-dimensional image and learning it in the form of a grayscale image.