• Title/Summary/Keyword: Insulation breakdown strength

검색결과 178건 처리시간 0.021초

Investigations on PD Characteristics of Thermal aged Palm and Corn Oil for Power Transformer Insulation Applications

  • Senthilkumar, S.;Karthik, B.;Chandrasekar, S.
    • Journal of Electrical Engineering and Technology
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    • 제9권5호
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    • pp.1660-1669
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    • 2014
  • Partial discharge (PD) detection plays a major role in the life time assessment of liquid insulation in power transformers. Many research works are being carried out to replace conventional mineral oil insulation in transformers by vegetable oils. It is necessary to understand the PD characteristics of vegetable oils before recommending them as an alternate for mineral oil. In this paper, the breakdown strength and PD characteristics of palm and corn oil were investigated in both unaged and thermally aged conditions. Laboratory experiments were performed as per IEC test procedures. PD signals were measured using wide band detection system. Phase resolved PD pattern of vegetable oils and mineral oil were compared. Effect of increase in voltage stress on the PD pattern of palm and corn oil were studied. Time and frequency domain analysis of PD pulses at needle-plane electrode configuration was carried out. Statistical analysis of PD pattern i.e. skewness and shape parameter variations with respect to applied thermal stress were also carried out. From the results, it is observed that palm and corn oils have better breakdown strength and PD characteristics even under long-term thermal stress and hence they can be used for power transformer applications.

Long-term and Short-term AC Treeing Breakdown of Epoxy/Micro-Silica/Nano-Silicate Composite in Needle-Plate Electrodes

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • 제13권5호
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    • pp.252-255
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    • 2012
  • In order to characterize insulation properties of epoxy/micro-silica/nano-silicate composite (EMNC), long-term and short-term AC treeing tests were carried out undr non-uniform electric field generated between needle-plate electrodes. In a long-term test, a 10 kV (60 Hz) electrical field was applied to the specimen positioned between the electrodes with a distance of 2.7 mm in an insulating oil bath at $30^{\circ}C$, and a typical branch type electrical tree was observed in the neat epoxy resin and breakdown took place at 1,042 min after applying the 10 kVelectrical field. Meanwhile, the spherical tree with the tree length of $237{\mu}m$ was seen in EMNC-65-0.3 at 52,380 min (36.4 day) and then the test was stopped because the tree propagation rate was too low. In the short-term test, an electrial field was applied to a 3.5 mm-thick specimen at an increasing voltage rate of 0.5 kV/s until breakdown in insulating oil bath at $30^{\circ}C$ and $130^{\circ}C$, and the data was estimated by Weibull statistical analysis. The electrical insulation breakdown strength for neat epoxy resin was 1,763 kV/mm at $30^{\circ}C$, while that for EMNC-65-0.3 was 2,604 kV/mm, which was a modified value of 47%. As was expected, the breakdown strength decreased at higher test temperatures.

액체 질소에서의 반합성지 AC 파괴 강도에 미치는 부분 방전의 영향 (Study of Partial Discharge Influence on AC Breakdown Strength of Laminated Ploypropylene Paper(PPLP) at Liquid Nitrogen)

  • 안드레프;김수연;이인호;김도운;신두성;김상현
    • 한국초전도ㆍ저온공학회논문지
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    • 제4권1호
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    • pp.105-109
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    • 2002
  • The short-term AC breakdown strength of laminated polypropylene insulating Paper (PPLP) has been studied for cold dielectric of high temperature superconductivity power cables. The design and operating conditions of the electrode system for studying of short-term breakdown strength of one-layer and multi-layer PPLP samples are discussed in liquid nitrogen(LN2) state. The influence of various operating factors (geometry and dimension of electrodes, speed of tested voltage, thickness of test sample) on the value of short-term AC breakdown strength at cryogenic temperature has been established.

에폭시 복합체의 절연신뢰도 및 파괴수명 예측 (Prediction of Insulation Reliability and Breakdown Life in Epoxy Composites)

  • 신철기;박건호;왕종배;김성역;이준웅
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1996년도 추계학술대회 논문집
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    • pp.260-264
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    • 1996
  • In this study, the dieiectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability . As a result. first of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature, and the breakdown strength of specimens because it is believed that the adding filler farms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. In the case of filled specimens with treating silane, the breakdown strength become much higher since the suggests that silane coupling agent improves interfacial combination and relays electric field concentration. Finally, from the analysis 7f weibull distribution. it was confirmed that as the allowed breakdown probability was given by 0.11[%].

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와이블 분포식을 이용한 에폭시 복합체의 절연 신뢰도 분석 (Analysis of Insulating Reliability in Epoxy Composites using Weibull Distribution Equation)

  • Park, No-Bong;Lim, Jung-Kwan;Park, Yong-Pil
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 2003년도 춘계종합학술대회
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    • pp.813-816
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    • 2003
  • The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were applied to Weibull distribution probability. First of all, speaking of dielectric breakdown properties, the more hardener increased, the stronger breakdown strength became at low temperature because of cross-linked density by the virtue of ester radical. The breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised and the electric field is concentrated. In the case of filled specimens with treating silane, the breakdown strength become much higher. Finally, according to Weibull distribution analysis, reducing breakdown probability of equipment insulation lower than 0.1 % level requires the allowable field intensity values to be kept under 21.5 MV/cm.

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Evaluation of Insulating Reliability in Epoxy Composites

  • Park, No-Bong;Yang, Dong-Bok;Lim, Jung-Kwan;Park, Yong-Pil;Lee, Hee-Kab;Kim, Gui-Yeul
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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    • pp.1200-1203
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    • 2003
  • The dielectric breakdown of epoxy composites used for transformers was experimented and then its data were applied to Weibull distribution probability. First of all, speaking of dielectric breakdown properties, the more hardener increased, the stronger breakdown strength became at low temperature because of cross-linked density by the virtue of ester radical. The breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised and the electric field is concentrated. In the case of filled specimens with treating silane, the breakdown strength become much higher. Finally, according to Weibull distribution analysis, reducing breakdown probability of equipment insulation lower than 0.1% level requires the allowable field allowable field intensity values to be kept under 21.5 MV/cm.

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친환경 GIS Spacer용, 에폭시-나노-마이크로실리카 혼합 콤포지트의 교류 전기적, 기계적 특성 (AC Electrical and Mechanical Properties of Epoxy-Nano-Microsilica Mixed Composites for Eco-Friendly GIS Spacer)

  • 박재준
    • 전기학회논문지
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    • 제67권9호
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    • pp.1181-1188
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    • 2018
  • In order to develop new insulating materials for GIS Spacer using environmentally friendly insulating gas, three kinds of dispersed liquid nano composites of solid epoxy /nano layered silicate filled material were prepared. And the epoxy/nano/micro silica composite was prepared by mixing epoxy/nano 3 phr dispersion/4 kinds of filler contents(40,50,60, 70wt%). The electrical insulation breakdown strengths of the nano and nano/micro mixed composites were evaluated by using 8 kinds of samples including the original epoxy. The mechanical tensile strength of the epoxy / nano / micro silica composite were evaluated, also. The TEM was measured to evaluate the internal structure of nano/micro composites. As a result, it was confirmed that the layered silicate nano particles was exfoliated through the process of inserting epoxy resin between silicate layers and the layers. In addition, dispersion of nano / micro silica resulted in improvement of electrical insulation breakdown strength with increase of filling amount of dense tissue with nanoparticles inserted between microparticles. In addition, the tensile strength showed a similar tendency, and as the content of microsilica filler increased, the mechanical improvement was further increased.

전기절연유의 절연파괴에 미치는 전극간격 및 곡률반경의 영향 (The Influence of Gap Length and Tip Radius on Breakdown of Electrical Insulating Oil)

  • 강성화;채홍인;이종필;임기조
    • 한국안전학회지
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    • 제19권1호
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    • pp.56-59
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    • 2004
  • In this paper, we investigated the influence of gap length and tip radius on breakdown of mineral based insulation oil. Applied voltages were DC and AC voltage. Electrode system was needle-plane structure. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}m$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. Electric breakdown strength at tip was calculated using Mason's equation contained geometric figure. As gap length increased, breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by the phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage, breakdown strength was higher when polarity of needle was negative than positive. It is because of the space charge effect in accordance with the influence of liquid motion.

에폭시 매입금구 표면거칠기에 따른 전기적, 기계적 특성 연구 (A Study on Mechanical and Electrical Properties at Interfaces Between Epoxy and ifs Molded Metal)

  • 김수연;하영길;이성진;김영성;박완기;김성진
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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    • pp.226-229
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    • 1999
  • Epoxy compound has been used as insulation material in electrical equipment for a long time because of its excellent electrical, mechanical and chemical properties. Nowdays, becoming higher voltage system, the properties of interface between epoxy and metal insert become more important. The breakdown voltage of epoxy compound for electric material is variable according to the surface roughness of metal insert. Generally, with metal insert sanding, the adhesion strength is enhanced and the breakdown strength is reduced. But in this study, we knew that the adhesion strength became enhanced but the breakdown strength didn\`t reduced with metal insert sanding. So in this study sanding. So in this study, we suggest the optimum interface condition by adjusting the surface roughness.

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Effect of Nanosilica on the Mechanical Properties and AC Electrical Breakdown Strength of Epoxy/Microsilica/Nanosilica Composite

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • 제13권6호
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    • pp.301-304
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    • 2012
  • Epoxy/microsilica (65 phr)/nanosilica (0~5 phr) composites (EMNC) were prepared in order to develop a high-voltage insulation material, where phr means parts per hundred relative to the epoxy oligomer. Tensile and flexural tests of the composites were carried out, and the AC electrical breakdown strength was measured, after which all the data were estimated by Weibull statistical analysis. As the nanosilica content increased, the tensile strength increased, and the highest value was 117.7 MPa in the EMNC system with 3 phr nanosilica, which was ca. 10% higher than that of the system without nanosilica. The value then decreased after 3 phr. The flexural strength and AC electrical breakdown strength showed the same tendencies as the tensile strength. The highest value of the flexural strength was 184.6 MPa in the EMNC system with 3 phr of nanosilica, which was ca. 15% higher than that of the system without nanosilica. The strongest value of the AC electrical breakdown strength was 79.0 kV/0.5 mm in the EMNC system with 3 phr of nanosilica, which was ca. 34% higher than that of the system without nanosilica.