• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1679-1681
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• 2004

Class-F and B resin-rich type insulating tapes are generally used for the ground wall insulations of respective air-cooled and water-cooled stator windings in larger turbine generators. In this paper, their electrical properties coupled with aging times in higher temperature than designed one in normal condition were experimentally investigated and the results of two comparative tests were presented on the existing class-F resin-rich type tape and a developed one after curing. The resin-rich tapes currently used arc composed of six and a half 3-layer sheets that arc structured with mica paper, the top and bottom supports of it respectively, and the epoxy resin to bind them tightly. The results for breakdown voltage and strength on the cured specimens were presented, which were composed of the unaged, the aged accelerated for one, two, and three thousand hours at 180 $^{\circ}C$. The surface and volume resistivities on them were measured and the results are also presented to make a comparative test for the initial electrical characteristics.

• 전기학회논문지
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• 제63권10호
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• pp.1461-1466
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• 2014

GIS(Gas Insulated Switchgear) is important power apparatus which have strong dielectric strength, supply electric power and is a part of the power system. Most substation type is configured as GIS. Recently, because of continuous increasement of GIS demand resulted from high quality & big capacity of electric power, the necessity of the preventive & diagnosis system is being expanded gradually. GIS partial discharge occurred on the UHF band is detected effectively by the method to IEC 60270 that recommend to be able to detect the apparent minimum discharge, 5 pC. Additionally, the UHF sensor should be installed to detect PD signal if Partial discharge signal, 5 pC occur in every part of GIS. Currently PD diagnosis system applying UHF sensor for GIS with various voltage level like 154 kV, 345 kV, 765 kV have been operated. And it is necessary to measure and analyze insulation breakdown phenomenon of inside GIS exactly. In this paper, we proposed Fat-dipole patch UHF sensor that is developed and more sensitive, excellent wide-range characteristic than the exising UHF sensor. And we performed KERI (Korea Electrotechnology Research Institute) reference test, which showed the excellent result for the all tests.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.224-224
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• 2009

본 연구는 여러종류의 에폭시 나노콤포지트의 절연파괴 강도에 대한 와이블 특성을 연구하였다. 여러 종류 나노콤포지트는 나노입자 형상의 변화 즉, 층상실리케이트(Layered Silicate)와 구상 입자(SiO2)의 충진함량변화를 통한 절연파괴특성을 연구하였다. 나노+마이크로입자에대한 두 개의 체적비를 통한 멀티-나노복합물을 구현하였고, 그 절연파괴 특성의 결과와 기계적특성으로 굴곡강도특성을 Weibull Plot을 통하여 분석하였다. 순수한 나노콤포지트보다 멀티나노콤포지트가 기계적특성에서 월등하게 나타내었고, 절연파괴강도역시 형상파리미터가 대단히 큰 결과를 얻었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.295-295
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• 2008

Water tree experiments were done for several types of cross-linked polyethylenes. Test method is followed by ASTM D6097. Polyethylene is divided for four subgroup. First One is chemically cross-linked general XLPE, and second one is chemically cross-linked tree-retardant XLPE, and the third one is silane cross-linked polyethylene made by monosil process, and the last one is silane cross-linked polythylene made by copolymer. Tree retardant XLPE shows the shortest water tree length. Cahemcally cross-linked general XLPE shows the longest water tree length. Silane cross-linked polyethylene by copolymer is similar to tree retardant XLPE and similar breakdown strength. So silane cross-linked XLPE by copolymer could be used for the the medium voltage cable which should have tree retardant characteristics.

• Advances in materials Research
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• 제1권1호
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• pp.93-107
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• 2012

Epoxy resin is widely used in high voltage apparatus as insulation. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. The addition of fillers can deteriorate electrical performance. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite materials with enhanced electrical, thermal and mechanical properties. In the present paper we have carried out a comparative study on dielectric properties, space charge and dielectric breakdown behavior of epoxy resin/nanocomposites with nano-fillers of $SiO_2$ and $Al_2O_3$. The epoxy resin (LY556), commonly used in power apparatus was used to investigate the dielectric behavior of epoxy resin/nanocomposites with different filler concentrations. The epoxy resin/nanocomposite thin film samples were prepared and tests were carried out to measure their dielectric permittivity and tan delta value in a frequency range of 1 Hz - 1 MHz. The space charge behaviors were also observed by using the pulse electroacoustic (PEA) technique. In addition, traditional epoxy resin/microcomposites were also prepared and tested and the test results were compared with those obtained from epoxy resin/nanocomposites.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.502-505
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• 2004

The purpose of this experiment is to modify diagnosis criterion of isothermal relaxation current(IRC) measurement equipment which is using for distribution cable diagnosis. We're using this system for several years in the field instead of DC leakage current measurement and lots of cables were replaced. But we have to investigate on the reliability of this equipment for our cables because we didn't carried out condition assessment of extracted cables after field diagnosis by this equipment. It is important thing for cable maintenance. If the replacement criterion is improper we can not prevent failures or will waste budget on account of replacement of the sound cables. In this papar we selected field installed cables and injected silicone fluid to the cables for insulation rehabilitation. In order to prove reliability of the diagnosis equipment we compared diagnosis results and AC breakdown strength according to operating time after silicone treatment. This is the results of the field test for 1 year.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권5호
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• pp.258-263
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• 2004

The purpose of this experiment is to modify diagnosis criterion of isothermal relaxation current(IRC) measurement equipment which is using for distribution cable diagnosis. We're using this system for several years in the field instead of DC leakage current measurement and lots of cables were replaced. But we have to investigate on the reliability of this equipment for our cables because we didn't carried out condition assessment of extracted cables after field diagnosis by this equipment. It is important thing for cable maintenance. If the replacement criterion is improper we can not prevent failures or will waste budget on account of replacement of the sound cables. In this paper we selected field installed cables and injected silicone fluid to the cables for insulation rehabilitation. In order to prove reliability of the diagnosis equipment we compared diagnosis results and AC breakdown strength according to operating time after silicone treatment. This is the results of the field test for 1 year.

• 전기학회논문지
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• 제65권5호
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• pp.819-824
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• 2016

The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 33.64 and 67.27 days at 110[$^{\circ}C$], equivalent to 40 and 80 years of aging at 50[$^{\circ}C$], respectively. These samples were referred to as CSPE-0y, CSPE-40y and CSPE-80y, respectively. As the accelerated thermally aged years of the CSPE increase, the insulation resistance[$\Omega$] at 20[Hz], 500[Hz], and 2[KHz], and the percent elongation [%EL] of the CSPE decrease. However, the dissipation factor($tan{\delta}$) at 20[Hz], 500[Hz], and 2[KHz], the apparent density[$g/cm^3$], the glass transition temperature and the melting temperature of the CSPE were increased. The period of time that the voltage has to be applied until electric breakdown of the CSPE-0y is longer than that of the CSPE-40y, and the CSPE-80y, but the dielectric strength of the CSPE-80y is lower than that of the CSPE-0y and the CSPE-40y. The differential temperatures after the AC and DC voltages are applied to CSPE-0y, CSPE-40y and CSPE-80y are 0.026~0.028[$^{\circ}C$], 0.030~0.042[$^{\circ}C$], 0.018~0.045[$^{\circ}C$], respectively. The variations of temperature for the AC voltage are higher than those for the DC voltage when an AC voltage is applied to CSPE-0y, CSPE-40y and CSPE-80y. It is found that the dielectric loss owing to the dissipation factor[$tan{\delta}$] is related to the electric dipole conduction current. It is ascertained that the ionic (electron or hole) leakage current is increased by the separation of the branch chain of CSPE polymer from the main chain of the polyethylene as a result of thermal stress due to accelerated thermal aging as well as by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$ after seawater soaking.

• 한국조명전기설비학회지:조명전기설비
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• 제1권2호
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• pp.74-81
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• 1987

고분자 절연재료에 전하주입시 발생하는 캐리어 트랩현상은 재료의 절연성을 저하시키는데 중요한 영향을 미치는 것으로 알려져 있다. 따라서 본 연구에서는 절연재료의 전기적 특성을 개선한다는 측면에서 캐리어의 거동을 파악하기 위해 내열성이 폴리프로필렌보다 우수한 이축 연신된 폴리프로필렌 필름(두께 $50\mu\textrm{m}$)을 선정하여 전계변화에 따른 열자격전류 스펙트라를 분석 검토하였다. 온도범위 303~413[K]와 전계범위 2~80[㎹/m]에서 열자격 전류의 변화를 살펴본 결과 전계 12[㎹/m]이하에서는 전하주입의 효과가 관찰되지 않았으나 전계가 점점 높아지면 트랩된 공간전하와 전극으로부터 주입된 공간전하가 형성되어 Hetero 및 Homo성 열자격전류 스펙트라가 나타나며 이는 결국 절연파괴를 야기시키는 것으로 예측되어진다. 또한 이축 연신된 시료가 미연신 재료보다 우수한 절연특성을 가지고 있음을 확인 할 수 있었다.