• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.76-78
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• 2001

In this paper insulation cover that being used in distribution line have been evaluated for aging characteristics. For evaluating its aging properties, we dismounted a variety of samples, like insulation covers for termination of deadend clamp, bushing, LA, COS and sleeve, in the fields. we performed mechanical properties test, electrical test, weathering test, etc. of these samples. And these samples are compared with virgin sample. Test results shows the bad mechanical strength in some part of samples. Especially, Insulation covers for the bushing terminations have cracks in the surface of samples.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.976-979
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• 1992

There are lots of problem which are delaminations and partial discharge of insulation materials in high-voltage rotating machines caused by mechanical, electrical and thermal aging. Several experiments have been aiming at finding the useful diagnostic parameters from the partial discharge characteristics by applying a new measurement techniques. This paper deals with the partial discharge characteristics (pulse height, pulse angle, pulse frequency spectrum and time interval), which may be a useful diagnostic concept in predicting insulation condition of mica/epoxy composite insulation materials, by using several measurement equipments (frequency spectrum analyzer. multichannel analyzer and time interval analyzer).

• 조명전기설비학회논문지
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• 제23권6호
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• pp.104-108
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• 2009

본 논문에서는 지중전력케이블을 대상으로 케이블의 절연열화특성 분석시험을 통해 케이블의 절연열화와 절연 진단결과 및 파괴강도와의 상관관계에 대한 실증연구를 수행하였다. 시험대상 선로의 제조결함 여부를 확인하기 위해 가교도분석, 핫오일테스트 등을 실시한 결과 제조결함은 없는 것으로 확인되었다. 진단대상 선로는 3상 모두 장기간 사용에 의해 열화가 많이 진전되었고, 특히 B상이 수트리 길이 및 화학구조결함 농도 면에서 가장 열화된 케이블인 것으로 판단되며, C상, A상의 순으로 열화정도가 다소 감소함을 확인하였다. 상기 결과는 진단시험 및 파괴 강도시험 결과와 일치하며, 따라서 열화시정수법을 이용한 진단장치가 열화상태가 심각한 케이블의 선별에 효과적인 진단법임을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.221-224
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• 1997

In this study we investigated the acting characteristics of Polymers for electrical insulation by UV radiation and salt water spray treatment. We used the Polymers such as EPDM, SR. PTFE. EVA. We measured contact angle and surface resistance to know the aging characteristic of Polymer surface. And we use SEM to observe the change of the surface shape. Dry flashover voltage test impulse voltage test were carried for the polymer insulator(EVA) . Through this experiment and the analysis we could know the polymers have a good resistance to weathering conditions like as salt spray UV irradiation and mix of them. And we can compare the aging characteristics between Polymers. As a result, we could know that the surface characteristics of PTFE is better than the other. And the degree, electrical characteristics is affected by change of surface shape is not big.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.404-405
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• 2009

Insulation diagnostic tests for high voltage motor stator winding were conducted to analyze the insulation characteristics. Test motors were manufactured same factory and year(1996). Insulation characteristics of moisture winding are different from those of deteriorative winding. Insulation resistance and disscipation factor test results are sensitive to moisture winding. AC current, disscipation factor tip-up and PD test results are sensitive to deteriorative winding. Also, Capacitance value for stator winding insulation material has characteristic of increasing in moisture winding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1896-1898
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• 2002

In this paper, to developing thermally and mechanically upgraded ones, we dismounted pole transformers used in the fields for over 13 years and conducted aged oil analysis. Also, when the cellulose and aramid papers in test cell were aging with oil at $130^{\circ}C$ for 3000 hours, with the testing period cellulose paper deteriorated more rapidly than the others. For example dielectric strength and dissipation factor of papers deteriorated with aging time. For evaluation of thermal aging characteristics, a mineral oil-immersed transformer was constructed with hybrid insulation system comprised of aramid paper and cellulose insulation. A Hybrid system has economic advantages. Cellulose materials are confined to cooler regions of the transformer winding. And aramid papers are served to insulate contact parts of hot conductors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기설비전문위원
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• pp.97-99
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• 2004

Liquid-immersed pole transformers have utilized an insulation system consisting of natural cellulose-based materials and mineral oil for many years. If the transformers are installed with the abruptly changing load over limitation, its insulation materials are apt to unexpected aging with high temperature. Therefore we have been conscious of developing a transformer that is more thermally stable then conventional types. To measure temperature distribution in the winding of conventional and newly designed transformers, temperature sensors were installed fordirect reading of oil and conductor temperatures at transformers. And we conducted accelerating aging test for these transformers. The measuring data had made use of the design to hybrid insulation system. Also we could find the possibility of this insulation system to apply in pole mounted transformers.

• 전기학회논문지
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• 제56권9호
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• pp.1561-1565
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• 2007

According to thermal degradation on power transformers, it is known that electrical, mechanical and chemical characteristics for power transformer's oil-paper are changed. In the chemical property, especially, when the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. Also the paper breakdown is accompanied by an increase in the content of various furanic compounds within the dielectric liquid. It is known that furanic components in transformer oil come only from the decomposition of insulating paper rather than from the oil itself. Therefore the analysis of furanic degradation products provides a complementary technique to dissolved gas analysis for monitoring transformers when we evaluate the aging of insulating paper by the total concentration of carbon monoxide and carbon dioxide dissolved in oil only. Recently, the analysis of furanic compounds by high performance liquid chromatography(HPLC) using IEC 61198 method for estimating degradation of paper insulation in power transformers has been used more conveniently for assessment of oil-paper. It is know that the main products which is produced by aging are 2-furfuryl alcohol, 2-furaldehyde(furfural), 2-furoic acid, 2-acetylfuran, 5-methyl-2-furaldehyde, and 5-hydroxymethyl-2-furaldehyde. For investigating the accelerated aging process of oil-paper samples we manufactured accelerating aging equipment and we estimated variation of insulations at $140^{\circ}C$ temp. during 500 hours. Typical transformer proportions of copper, silicon steel and iron have been added to oil-paper insulation during the aging process. The oil-paper insulation samples have been measured at intervals of 100 hours. Finally we have analyzed that 2-furoic acid and 2-acetylfuran products of furanic compounds were detected by HPLC, and their concentrations were increased with accelerated aging time.

• 한국안전학회지
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• 제15권4호
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• pp.78-87
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• 2000

The $\gamma$-ray irradiation and aging effects on electrical characteristics of $^{60}Co$ $\gamma$-ray irradiated ethylene-propylene-diene-terpolymer(EPDM) contained with 1 to 3phr phenolic and quinolinic antioxidants as antirads were investigated. The marked effects of type and amounts of the antioxidant on the volume resistivity and AC breakdown strength of the $\gamma$-ray irradiated EPDM are different. A phenolic antioxidant(IR 1010) contribute to improving the electrical insulation properties on the EPDM better than quinolinic antioxidant(Kumanox RD) during irradiation. In aging the irradiated EPDM specimens contained antioxidants at room temperature in air, it was shown a improvement of insulation properties due to radical scavenging and crosslinking of EPDM aged until 360 days.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권5호
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• pp.213-221
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• 2002

In order to improve the reliability of XLPE cables, it is necessary to find the useful diagnostic parameter according to long term aging. This paper described the change of partial discharge(PD) phase Properties of XLPE cable insulation with branch type electrical tree degradation. for long term aging. To understand the PD Properties with $\phi$ -q-n distributed shape of XLPE insulation, specimens were prepared by 22.9㎸ distribution cable and made in a type of block(16${\times}$16${\times}$3[mm]). Ogura needles having tip radius of l0${\mu}{\textrm}{m}$ were inserted into each block pieces. The measuring system was consisted of PD detector, digitizer for digital conversion, VXI system for signal processing. The PD properties of the specimens were measured from initiation of tree to breakdown and their characteristics were analyzed. We analyzed the relationship between electrical properties(PD Quantity, PD initiation angle, PD extinction angle, PD occurrence angle : (PD extinction angle - PD initiation angle)) and the normalized aging rate. We found PD parameter, PD initiation angle and occurrence angle, which are a useful diagnostic parameter in estimating the branch type electrical tree for XLPE insulation condition.