• 조명전기설비학회논문지
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• 제22권4호
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• pp.114-120
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• 2008

일반적으로 22.9[kV] 이하의 케이블은 가교폴리에틸렌(XLPE)을 절연체로 사용하고 있다. XLPE내부의 결함으로 인한 사고로 경제적 및 인명피해가 발생한다. 이러한 사고에 대한 처리 기준이 마련이 되어 있지 않아 사고처리의 체계화가 시급히 필요한 실정이다. 본 연구에서는 XLPE 케이블의 사고 요인이 되는 전기적 열화현상에 대한 자료구축을 위하여 XLPE에 곡율반경이 $10[{\mu}m]$인 침천극을 삽입하여 절연파괴, 트리형상 및 연면방전 시료를 제작하였다. 단시간 파괴는 AC 60[Hz]의 전압을 1[kV/sec] 상승하였으며, 장기과전의 경우 AC 60[Hz]의 전압을 12[kV] 및 17[kV]를 인가하여 전기적 열화 특성에 대하여 실험을 하였다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권5호
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• pp.165-170
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• 2003

This paper presents development of solid core suspension disc insulators (cap and cap suspension disc insulator) for replacing cap and pin suspension disc insulators in overhead transmission and distribution lines which expose to lightning discharges. By this means the punctured problem caused by steep front surge voltage created by lightning discharge on the lines can be solved. The solid core suspension insulator was designed and constructed based on the dimensions of conventional suspension disc insulators (cap and pin insulators). The insulators are made of alumina porcelain. The electrical and mechanical characteristics of the solid core suspension insulators were carried out. The puncture test was performed in the air by applying steep front impulse voltage with amplitude about 2.5 per unit of 50% flashover (CFO) of the insulator unit at negative standard lightning impulse $1.2/50\;\mu\textrm{s}$ with steepness up to $9200\;kV/\mu\textrm{s}$. The testing results show that solid core suspension disc insulators are not punctured eventhough the steepness of the steep front impulse voltage was increased up to $9200\;kV/\mu\textrm{s}$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1687-1689
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• 1998

In this work, the behaviours of conducting wire type particles within the coaxial electrode gap energized with high ac voltage have been systematically investigated using charge simulation method. For this, spheroidal charge is adopted as a image charge for the CSM analysis in order to calculate the acquired charge of the particles which are erected on the surface of the outer electrode. For this purpose, the effects of the lengths and diameters of Cu, Al particles in gas insulated system have been studied by a numerical computation and particle lifting voltage, lifting field, breakdown voltage, acquired charge and travelling distance have been considered. From this, we understand that the particle behaviours have different characteristics according to the particle lengths and diameters. And a possible countermeasure, based on the proposed simulation, has been provided with a view to estimating the flashover voltage of $SF_6$ gas under the 1 atm.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.85-92
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• 2008

많은 나라에서 가공 송전선로 아래에서 발생된 산불에 의해 계통 섬락사고를 일으키고 있다. 본 연구에서는 상용주파수 교류 및 직류 고전압을 인가하였을 때, 연소화염에 의해 전력선의 절연강도가 저하하는 특성을 조사하기 위해 수직배열 전력선에 대한 모의조건에서 다양한 실험을 수행하였다. 실험 결과, 화염이 없는 경우에 비해 연소 화염이 존재하면 화염의 거리(h)에 따라 절연파괴전압은 크게 저하되는 것으로 나타났다. 도체와 화염의 거리(h)가 작을수록 절연파괴전압이 감소하였으며, 교류전압 인가 시, h=9[cm]일 때 평균 46.2[%], h=3[cm]일 때 평균 62.5[%] 저하된 것으로 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1400_1401
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• 2009

In this paper describes the comparisons of the surface flashover characteristics according to the change of the insulation media by experimental GIS(Gas Insulated Switchgear) chamber in accordance with change of pressure(P) and electrode distance(d). The using insulation medias are $SF_6$, Dry-Air, I-Air(Imitation Air, $N_2$ : $O_2$ = 79[%] : 21[%]), $N_2:O_2$ mixture gas and pure $N_2$. In this study, in order to compare the properties $SF_6$ and order insulation gas, we investigated the properties of the various insulation media with a knife to knife electrode under ac high voltage application. The gas pressure was changed from 1 to 5[atm]. as a result, it was found that dielectric strength is $SF_6$ > I-Air > Dry-Air and the best environmental preservation gas is Dry-Air.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.616-624
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• 2015

Flashover of power transmission line insulators due to contamination is a major threat to the reliable operation of power system. This paper deals with the analysis of leakage current characteristics of polymeric insulator using S-Transform technique in order to develop a better diagnostic tool to identify the surface condition of outdoor polymeric insulators. In this work, experiments were carried out on 11 kV silicone rubber insulator under AC voltage at different pollution levels. Moving average technique was adopted to find the trend followed by LC peak at different relative humidity conditions. S-Transform was used to find the relationship between energy and frequency content of the leakage current signal with respect to increase in pollution level over a period of time. From the S-Transform time-frequency contour analysis, point of transition to severe arcing due to increase in pollution and its thershold limit were evaluated. Reported results show that the surface condition of insulators could be easily identified from the S-Transform time-frequency analysis of leakage current signals.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.335-336
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• 2008

Overhead transmission lines are mainly crossing mountainous area. They are easily affected in weathers like typhoon, strong wind, lightning, heavy rain, or heavy snow. Sometimes these weathers cause transmission line faults. A lightning flashover is most often fault. Nowadays lightning density in KOREA is growing high and lightning flashovers occur more often. A lightning flashover on transmission line is mostly cleared by momentary operation of a circuit breaker, so power failure happens rarely. However, when both circuits trip simultaneously due to the lightning flashovers on double circuit transmission line, short time power failure and voltage drop happen. KEPCO has used transmission line arresters to avoid double circuit simultaneous trip out since 2003. And transmission line arresters cannot be installed with KEPCO's present metal fittings, so various fittings have been used for each transmission line arrester manufacturer. This paper introduces development and standardization of arc-horn and metal fittings for transmission line arrester which can be used for both existing lines and new lines in KEPCO.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.314-318
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• 2011

Recently, ultrasound, infrared detector, V-I characteristic, gas analysis, UV (ultra-violet rays) camera etc. is used as inspections and diagnoses of the safety of power equipment. Especially, UV camera have attracted a great deal of interest from the view point of easy judgement. UV camera is used corona discharge. One of the most important and difficult problems to be solved filer design, materials and corona discharge. This paper is studied on the temperature characteristics, UV generation and shape analysis and corona pulse count according to the electrode distance and applied voltage. Also, Corona discharge characteristics in air are analyzed using prototype UV camera of Korea. UV generation due to surface discharge of AC is higher than that of DC.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.135-140
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• 2020

An experimental study was conducted using the tracking wheel test (IEC 62217) method for evaluating the performance of insulator materials, in particular ethylene propylene diene monomer (EPDM) and silicone rubber. In addition, we studied the tracking characteristics resulting from applying the same method for the shape of the insulator housing, that is, the performance of regular and alternating sheds. The evaluation parameters were leakage current, surface characteristics, SEM, EDX, hydrophobicity, and temperature distribution; likewise, we applied the commercial frequency dry (and wet) flashover voltage test. We found that the regular shed had a greater leakage current than the alternating shed and that the recovery of the hydrophobicity in terms of rest time was greater than that of the EPDM in terms of leakage current. All of the regular-shed insulators of silicone rubber had tracking traces and choking on the sheath parting line, while the alternating shed showed only choking at the interface but no tracking traces. Therefore, it can be concluded that the commercial frequency wet flashover voltage of the silicone rubber with regular shed before and after the tracking wheel test is higher than that of the alternating shed.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.279-282
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• 2005

Morden electronic equipments are becoming very important in information oriented society, but they are vulnerable to lightning surges. Soil resistivity in the vicinity of grounding electrodes my be affected by the current flowing from the grounding electrodes into the surrounding soil. Electrical conduction in soils depends on the grain size, compactness, and variability of the grain sizes. When a high current is injected into the soil, and the breakdown phenomenon occur. In the present work, Electrical behaviors related to discharge in soils were investigated. The breakdown voltages in soil were lower than that sparkover voltage in air. The breakdown voltage in the gravel layer is relatively low, and the breakdown was caused by the flashover through the surface of gravels