• 에너지공학
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• 제25권3호
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• pp.18-26
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• 2016

대부분의 변압기에 사용되고 있는 절연유는 석유계 원료를 이용한 광유계 절연유였으나 유출시 환경오염, 낮은 인화점으로 인한 화재 위험성을 가지고 있어 보다 친환경 식물성 원료를 활용한 절연유 도입이 최근 검토되고 있다. 그러나 식물성 절연유의 높은 생분해성과 인화점으로 절연유로서의 높은 적용가능성에도 불구하고 장기운전에 의한 열화가 미치는 영향에서는 아직 많은 연구가 필요한 실정이다. 따라서 본 연구에서는 변압기의 구성요소를 감안하고 실제 운전조건보다 높은 $150^{\circ}C$에서 2주간의 가속열화 시험을 통해 전산가, 수분, 절연파괴전압 등의 주요물성 변화를 통해 식물성 절연유 산화특성과 이 과정에서 생성되는 용존 가스 분석을 실시였다. 이를 통해 식물성 절연유가 기존 광유계 절연유 대비 친수성에 의한 전산가 상승에도 불구하고 절연성능을 유지하는 특징을 가지고 있으며 가스 성분 비교를 통해 주어진 온도 조건에서 우수한 열안정성을 나타내고 있음을 확인하였다.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1676-1678
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• 2004

Class-F resin-rich type insulating tapes are generally used for the groundwall insulations of the large turbine generators with air-cooled and hydrogen-cooled stator windings. In this paper, mechanical strength properties degraded over aging time in higher temperature than designed one in normal condition were experimentally investigated and the results of comparative tests were presented on the existing class-F resin-rich type tape and a developed one after curing. The resin-rich insulating tapes with composite material of Mica/Epoxy/support currently were used in this test. The tests for tensile and flexural strength properties were conducted with the specimens which were composed of unaged and the aged specimens accelerated for one, two, and three thousand hours at 180 $^{\circ}C$. The tensional strength was only measured for the unaged specimens and the results are also presented to make a comparative test for their initial mechanical characteristics.

• 한국농촌건축학회논문집
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• 제15권4호
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• pp.17-24
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• 2013

Rural community in Korea being changed to aging community, declining population and income loss by the industrialization and the urbanization. The weak class in rural is confronted with more poorly environment. So it is needed to check the quality of the weak class's house in rural. Basically proposes of this paper is to find ways about rural housing improving and the vitality of rural community. This paper contents rural housing problems through the paper review and house repair characteristics for the weak class. Data for statics analysis were obtained from house repair support program for the weak class in Jeonnam province from 2011 to 2012. The results of this paper are as follow: First, house repair items ranking for the weak class in rural was insulation & heating, toilet, structure, indoor environment, electricity, outside and kitchen & waterproof. This result was reflected that weak class's energy bills is high ratio compared with income. Second, health facilities were improved for the socially disadvantaged's convenience in considering that most of weak class is a senior. Last, most of houses for weak class in rural are old clay wall and block wall. So these houses are reinforced the wall for structural safety.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.901-903
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• 1998

Crosslinked Degree is an important factor to determine dielectric property of crosslinked polyethylene(XLPE) used for the insulation material in power cables. Recently, though it is necessary to investigate electrical properties according to crosslinked degree as a part of the whole characterization of cable. it is not examined closely. In this study, crosslinked degree of samples were measured according to temperature and holding time of crosslinking, electrical tree characteristics of these samples were analyzed by crosslinked degree and applied temperature that was changed from normal temperature to operating temperature of power cables. As a result. when the crosslinked degree was low, dielectric properties were decreased and influence of temperature was increased. but the crosslinked degrees were high. initiation voltages of treeing were increased and dielectric properties were improved. It is proved that the optimum. crosslinked degree was one of most important factor for aging time and residual lifetime of power cable.

• 한국전기전자재료학회논문지
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• 제20권3호
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• pp.273-280
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• 2007

In this paper, the ZnO surge arrester performance of power distribution class has been studied under different manufacturing conditions such as housing materials(polymeric, porcelain), interface sealants and one-body molding type. In the recent years, the polymeric ZnO surge arresters have been developed and put into operations based on their excellent characteristics. For polymeric surge arresters, the inner gas volume is extremely small, especially in solid insulation polymeric arresters there are not any gas volume inside arresters in the structure due to polymeric materials are filled into the internal gas volume. The sealing integrity is related to safe operation of surge arrester, the prime failure reason of porcelain housed arresters is moisture ingress. In this paper, the sealing integrity of polymeric surge arresters is investigated with moisture multi-aging test and ingress test. The evaluation techniques are used to inspect the sealing integrity of polymeric arresters, including leakage current, surface temperature, reference voltage and dissipation factor.

• 한국안전학회지
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• 제34권3호
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• pp.8-14
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• 2019

Many electrical socket-outlet fire accidents take place not only in homes but in the offices each year. The causes are mostly faulty constructions, managerial problems and carelessness. Construction and managerial flaws can be resolved by regular or special inspections, but carelessness is not solvable through inspections. Such carelessness can be related to the consumption capacity of electrical socket-outlets presently, the rated current of electrical socket-outlets is based on 16A. However, even at 16A, the heat generated in the insulator of an electrical socket-outlet varies due to such factors as part damage and environmental conditions of use. To explore this situation, the study conducted an experiment to analyze thermal relationship by applying 10A, 20A, and 30A currents. To secure reliability, the study employed thermal analysis simulation and compared the thermal relationship in the same current value. The experimental and simulation values were found to be similar and therefore, diverse current values were replaced with the simulation. At 30A, the temperature was found to rise to at least $169.9^{\circ}C$ which had worked as a sufficient amount of energy to bring the insulation aging of insulator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1621-1623
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• 1999

Recently, high voltage outdoor ploymer insulators have been widely used commercially owing to their excellent electrical and mechanical properties, superior comtamination flashover performance, light weight, easy installation or handing, no maintenance during service, competitive price and so on. compared to porcelaain and glass insulators. For instance, silicone rubber(SR) for polymeric insulators specially has much superior insulating and anti-pollution performance due to its specific hydrophobicity even in severe contaminated environments. We have investigated surface discharge current characteristics of silicone rubbers(SR) for HV outdoor composite insulation specimen under accelerated aging codition using a computer measuring system. The relations of average leakage current and surface discharge current repetition rates and discharge current amplitude, the distribution of discharge current amplitude were studied to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• 한국건설순환자원학회논문집
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• 제5권1호
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• pp.131-138
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• 2010

본 연구에서는 보통포틀랜드 시멘트(이하 OPC)제조과정의 분쇄공정 중 밀출구에서 배출되는 비교적 가격이 저렴하면서, 수화열면으로도 효과일 것으로 예상되는 입자분포를 갖는 시멘트(이하 CC)를 대상으로 플라이애시(이하 FA)와 고로슬래그 미분말(이하 BS)를 복합치환하는 3성분계 저발열 시멘트로의 개발 가능성을 검토하기 위하여 유동성, 강도, 간이단열온도 상승량 등 기초적인 특성에 대하여 분석하고자 한다. 실험결과로 유동성은 CC의 치환율이 증가함에 따라 저하하는 경향을 보였고, FA+BS의 치환율이 늘어남에 따라 증가하는 경향을 나타냈다. 공기량은 CC의 치환율이 증가함에 따라 미소하게 감소하는 경향을 나타냈고, FA+BS의 치환율이 증가함에 따라 감소하였다. 응결특성으로 CC 및 FA+BS의 치환율이 증가 할수록 응결 시간은 지연되었다. 간이 단열에 의한 온도 상승량은 전반적으로 CC 치환율이 증가할수록, FA+BS의 치환율이 증가할수록 피크온도는 감소하였고, 이후 온도저하가 완만해 지는 경향을 나타냈다. 압축강도는 CC 및 FA+BS 치환율이 증가할수록 저하하였는데, 재령이 경과함에 따라 장기강도는 Plain과 동등하거나 동등 이상의 강도를 발현 하였다. 종합적으로 CC에 FA+BS를 치환하였을 때 유동성 및 공기량은 저하하는 경향을 나타냈으나, 수화열 면에서 양호한 저감효과를 보여 3성분계 저발열 시멘트로의 개발이 가능성할 것으로 사료된다.

• 한국안전학회지
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• 제30권5호
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• pp.1-7
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• 2015

This paper is aimed to analyze the electrical and thermal signal such as ignition possibility, ignition time, thermal characteristics and arc fault power that are associated with electrical fire in case of the occurrence of series arc at IV wiring used for interior wiring at commercial power source. In order to analyze the signal, series arc was induced by generating the constant vibration through vibrating device in the one phase (R phase) and ignition possibility was analyzed along the condition of current value by adding cotton material to the contact point of wiring. The ignition time is shortened as the electric current value increased, burning time is not associated with current value and the temperature rose up to $740^{\circ}C$ though it was not ignited. It was checked out that the temperature was the energy source enough that can generate the fire related with insulation aging of wiring and the inflammable. The possibility of electrical fire by series arc was shown as more than 12% at 5A, more than 42% at 20A and arc showed 27W at 5A, 180W at 20A. It was confirmed that the possibility of electrical fire exists at the condition as above and the circuit breaker did not operate. This data can be used as the reference value for the investigation of electrical fire or development of the circuit breaker.