• 제목/요약/키워드: Insulation capability

검색결과 58건 처리시간 0.025초

진공차단기 3상 동시 차단시의 서지 특성 분석 (Surge Characteristics Analysis of Three-phase Virtual Chopping at Vacuum Circuit Breaker)

  • 김종겸
    • 전기학회논문지
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    • 제67권9호
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    • pp.1159-1164
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    • 2018
  • Vacuum circuit breakers(VCB) are widely used for current interruption of high-voltage inductive loads such as induction motors. This VCB can be chopped off before the current zero due to its high arc-extinguishing capability. One of the outstanding features of VCB is that it can cut off high frequency re-ignition current more than other circuit breakers. If the transient recovery voltage generated in the arc extinguishing is higher than the dielectric strength of the circuit breaker, a re-ignition phenomenon occurs. The surge voltage of the re-ignition is very high in magnitude and the steepness of the waveform is so severe that it can act as a high electrical stress on the winding. If the high frequency current of one phase affects the other two phases when the re-ignition occurs, it may cause a high surge voltage due to the virtual current chopping. If the magnitude of the voltage allowed in the motor winding is high or the waveform level is too severe, it may lead to insulation breakdown. Therefore, it is necessary to reduce the voltage to within a certain range. In this study, we briefly explain the various phenomena at the time of interruption, analyzed the magnitude of the dielectric strength and the transient recovery voltage at the simultaneous three-phase interruption that can give the greatest influence to the inductive load, proposed a method to reduce the impact.

불평등 전계에서 $SF_6/CF_4$ 혼합가스의 절연내력과 PD특성 (Breakdown Voltage and PD Characteristics of $SF_6/CF_4$ Mixtures in Nonuniform Field)

  • 황청호;성허경;허창수
    • 전기학회논문지
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    • 제57권4호
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    • pp.635-640
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    • 2008
  • New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.

접합유리용 고분자 필름의 물성 및 음향학적 특성 분석 (Analysis of the Polymer Properties and Sound Characteristics of Interlayer Films for Laminated Glass)

  • 고상원;홍지영;선우예림;김영준
    • 한국철도학회논문집
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    • 제19권1호
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    • pp.1-10
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    • 2016
  • 본 논문은 고속열차 객실 내 유리창의 차음 성능을 향상시키기 위한 기반연구로, 접합유리에 사용되는 고분자 필름의 물성과 음향학적 특성을 분석하여 그 상관관계를 살펴보고자 하였다. 기존에 사용되고 있는 PVB(polyvinyl butyal) 필름 및 다른 단량체 비율을 가지는 PVB 유도체, 그리고 유리 사이 차음재로 사용가능 한 PC(polycarbonate)의 동적기계적 특성을 분석(DMA)하였다. DMA 분석을 통해 상온에 가까운 온도범위에서 유리전이온도($T_g$)를 가지며 tan ${\delta}$(loss tangent) 값이 큰 것으로 나타난 PVB-HEMU 시편의 댐핑(damping) 성능이 가장 우수할 것으로 예측하고, 이를 고속철도 차량의 접합유리창과 동일한 구조에서의 투과손실 시험과 해석을 통해 검증하고자 하였다. 접합필름의 종류에 따른 유리창 투과손실 값을 투과손실 측정(인텐시티법)과 FE 해석을 이용해 도출하고, 고분자 필름의 물성과 음향성능 간 상관관계 분석을 위한 기초자료를 구축하였다.

뇌임펄스전압에 대한 SF6와 dry-air의 절연특성 (Dielectric Characteristics of SF6 and Dry-Air Gases under Lightning Impulse Voltage)

  • 이봉;유양우;김동규;이복희
    • 조명전기설비학회논문지
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    • 제24권8호
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    • pp.142-149
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    • 2010
  • 본 논문은 준평등전계에서 뇌임펄스전압에 대한 $SF_6$와 dry-air의 절연파괴 특성에 대하여 기술하였다. 준평등전계로 사용된 구-평판전극계의 전계이용률은 71[%]이다. $SF_6$는 0.1~0.2[MPa] 범위에서, dry-air는 0.2~0.6[MPa]에서 $SF_6$와 dry-air의 절연파괴전압을 임펄스전압의 극성과 가스압력에 따라 측정 분석하였다. 그 결과 뇌임펄스전압에 대한 두 가스의 절연파괴전압은 정극성이 부극성보다 높았으며, $SF_6$의 절연파괴전압이 dry-air의 절연파괴전압보다 약 2.67배정도 높았다. 본 연구결과는 뇌서지에 대하여 우수한 성능을 가지는 배전기기에서 $SF_6$의 대체가스 성능 평가에 유용한 정보가 될 것이다.

실리콘 고분자 수지의 버클링을 통한 스틸기반 태양전지의 효율 향상 (Buckling Formation on Steel-Based Solar Cell Induced by Silicone Resin Coat and Its Improvement on Performance Efficiency)

  • 박영준;오경석
    • Korean Chemical Engineering Research
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    • 제57권4호
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    • pp.519-524
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    • 2019
  • 스테인리스 스틸을 사용한 태양전지는 효율성이 낮지만, 패시배이션을 방지하는 목적의 추가적인 막을 설치하지 않아도 되는 장점을 가지고 있다. 본 연구에서는 스테인리스 스틸을 기반으로 하는 a-Si:H 박막 태양전지 제조에 고분자 재료인 실리콘 수지를 도입하였다. 실리콘 수지의 사용 목적은 스틸표면의 평탄화와 전기 절연성을 도입하는 것이다. 초기 공정에서, 스테일리스 스틸의 표면에 실리콘 수지를 스핀코팅을 통해 $2{\sim}3{\mu}m$ 두께로 코팅하였다. 이후 증착법을 이용하여 알루미늄 박막 코팅을 시도하였다. 알루미늄 증착시, 마이크로미터 크기의 실리콘 수지 표면위에 버클링이 형성되었다. 형성된 실리콘 수지 위로 반도체층 도입 등 추가적인 박막 공정을 실시하였으며, 박막층에 유지된 버클링은 광산란 효과를 증가시켜 태양전지의 효율 향상으로 연계되었음을 알 수 있었다.

고성능 에너지 저장 소자를 위한 니켈 구조체에 담지된 니켈 코발트 수산화물의 나노 형상 제어 (Nano-Morphology Design of Nickel Cobalt Hydroxide on Nickel Foam for High-Performance Energy Storage Devices)

  • 신동요;윤종천;하철우
    • 한국재료학회지
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    • 제31권12호
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    • pp.710-718
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    • 2021
  • Recently, due to high theoretical capacitance and excellent ion diffusion rate caused by the 2D layered crystal structure, transition metal hydroxides (TMHs) have generated considerable attention as active materials in supercapacitors (or electrochemical capacitors). However, TMHs should be designed using morphological or structural modification if they are to be used as active materials in supercapacitors, because they have insulation properties that induce low charge transfer rate. This study aims to modify the morphological structure for high cycling stability and fast charge storage kinetics of TMHs through the use of nickel cobalt hydroxide [NiCo(OH)2] decorated on nickel foam. Among the samples used, needle-like NiCo(OH)2 decorated on nickel foam offers a high specific capacitance (1110.9 F/g at current density of 0.5 A/g) with good rate capability (1110.9 - 746.7 F/g at current densities of 0.5 - 10.0 A/g). Moreover, at a high current density (10.0 A/g), a remarkable capacitance (713.8 F/g) and capacitance retention of 95.6% after 5000 cycles are noted. These results are attributed to high charge storage sites of needle-like NiCo(OH)2 and uniformly grown NiCo(OH)2 on nickel foam surface.

설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제26권12호
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

경량 알루미늄 허니콤 판재의 제작 및 특성 평가 (Fabrication and Characterization of Aluminum Honeycomb Panel)

  • 김기주
    • 한국산학기술학회논문지
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    • 제19권1호
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    • pp.666-671
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    • 2018
  • 허니콤 판재(honeycomb panel)는 벌집 모양의 코어(core) 양쪽면에 표면판재를 부착시켜 만든 판재이다. 허니콤 판재는 비강도가 뛰어나며, 재료에 압축하중이 가해졌을 때 재료가 수차례의 좌굴을 반복하기 때문에 에너지 흡수성이 우수하여 내충격성이 요구되는 부위에 사용하기에 적합하다. 특히 최근에는 수송기기의 경량화에 대한 요구가 증가함에 따라 알루미늄 허니콤 판재를 자동차 및 고속전철 등의 차체 재료로 이용하려는 연구가 진행되고 있다. 이 밖에도 허니콤 판재는 흡음성과 평활성이 우수하며, 단열성과 내피로성도 우수하다. 연료 경제성을 증가시키기 위하여 알루미늄 합금 소재와 같은 경량 소재를 허니콤 판재 주 재료로 사용하여 무게를 감량시키는 것에 관한 연구를 진행 하였다.본 연구에서는 허니콤 판재의 설계기술, 알루미늄 허니콤 코어 및 허니콤 판재 제조 기술에 대한 연구를 수행하였으며, 또한 제조된 허니콤 판재의 각종 기계적 특성평가를 행하여 그 결과를 바탕으로 알루미늄 허니콤 판재의 제조 공정 설계, 판재 제작 및 특성 평가방안을 마련하였다. 연구결과 허니콤 판재의 우수한 에너지 흡수성은 코어 버클링의 반복에 기인하며 압축강도가 높을수록 접합면적당 강도 또한 높은 값을 나타내었다.