• Fire Science and Engineering
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• v.32 no.2
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• pp.48-56
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• 2018

This paper reports the results of a study on the over-current characteristics of IV insulated wire sheath according to accelerated degradation. In order to examine the degradation of a IV insulated wire sheath through insulation, acceleration degradation experiments were performed using the Arrhenius equation of acceleration life test models; test samples with equivalent lives of 0, 10, 20, 30 and 40 years were prepared. Then allowed currents with over-current of 100%~500% were introduced to measure the times of first generation of smokes and carbonization in the wire sheath, and it was found that the times of first generation of smokes and carbonization in the wire sheath decreased as the equivalent life increased. In more detail, when 270% over-current is applied, the electrical fire risk of equivalent life of 40 years increased by approximately 3.2 times based on equivalent life of 0 years. Also, when the over-current was 255% and 260%, carbonization occurred only in the equivalent life of 40 years, and the fire risk according to the accelerated degradation was increased dramatically. In addition, FT-IR and SEM analyzes were used to confirm the characteristics and surface changes of IV insulated wire sheath according to the equivalent life.

• Fire Science and Engineering
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• v.22 no.5
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• pp.43-47
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• 2008

Recently SIMS has attracted interest as new technique to distinguish the primary and the secondary arc beads. A Cs+ primary ion beam was used to detect the $^{12}C^-$, $^{63}Cu^-$, $^{18}O^-$, $^{35}Cl^-$ secondary ions which are formed during depth profiles in the copper wires. In this work, we studied thermal diffusion in the copper wire which are occurred with supplying over-current. The results demonstrated that Carbon and Chloride are diffused in PVC-coated copper wire deeper than none PVC-coated. However Oxygen showed the reverse diffusion property.

• Rubber Technology
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• v.19 no.1_2
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• pp.11-20
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• 2018

• Fire Science and Engineering
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• v.33 no.2
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• pp.114-123
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• 2019

The paper relates to a study on the changes in performance of insulation sheath resulting from accelerated degradation of IV and HIV insulated wire. To assume insulation degradation of IV and HIV insulated wire, accelerated life tests using Arrhenius equation were conducted among accelerated life test models, and experimental samples of 0 year, 10 years, 20 years, 30 years, and 40 years in equivalent life were produced. Whereas the maximum tensile load were increased as accelerated degradation of IV and HIV insulated wire progressed, elongation percentage, rupture time, and flexibility of insulated wires were found to be gradually reduced. According to the additional surface analysis results for the insulated wires per equivalent life using a scanning electron microscope, mechanical properties of the insulator were observed to be reduced as insulation degradation resulting from aging progressed since phenomena such as formation of crystalline structures and perforation, etc. occurred on the sample surface with progression of accelerated degradation. Consequently, institutional replacement of insulated wires and preparation of repair times considering performance degradation of the insulator installed inside buildings are considered necessary in order to prevent in advance the risks of electrical fire resulting from degradation in insulation performance.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.37-48
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• 2006

• Congress of the korean instutite of fire investigation
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• 2010.12a
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• pp.80-90
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• 2010

대부분의 전기화재는 전기제품의 전원코드나 확장형 콘센트 등 저압 배선에서 주로 발생한다. 최초발화에 기인한 단락흔(1차 단락흔)의 외형적 판단기준을 제시하고자 발화원인이 규명된 전기화재의 감정사례로부터 비닐평형코드에 형성된 단락흔의 형태학적 비교분석결과 단락흔 자체 형태만으로 1차단락으로 판정하기는 용이하지 않지만 1차 단락흔은 2차 단락흔과 달리 용융방울이 미세하게 형성되고, 흑색으로 착색되는 경향이 있으며, 특히 절연피복의 손상을 줄 수 있는 선행된 원인이 있는 곳에서 만 특징을 나타내는 것을 알 수 있었다.

• 전기의세계
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• v.24 no.6
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• pp.50-55
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• 1975

PE(polyethlene)가 절연재료로서 지니는 특징은 (1)전기절연성이 크고 내전압이 높다. (2)무극성분자 구조이기 때문에 특히 고주파유전특성이 우수하다. (3)내수, 내습성이 있다. (4)경량이며 비교적 기계적 특성이 좋고 가격도 저렴한 편이다. 등등이라 하겠다. (1)(3)(4)등과 같은 특징을 중시하여 전력 cable의 절연피복으로 사용되었으며 (2)의 특징에 유의하여서는 통신선의 피복재로 애용되고 있다. 그러나 PE의 단점은 일반 타수지와 마찬가지로 부열성이 약한 점이다 .실로 저밀도 PE는 110.deg.C, 고밀도 PE의 경우는 125.deg.C부근에서 녹아 흐르기 시작한다. 이와 같은 단점을 개선하는 방법으로 분자쇄간을 가교시켜 3차원적 망상 구조로 만들어 고온에서의 분자쇄유동을 억제함으로 내열성을 높이는 기술이 개발되어 왔으며 이를 위한 가교방법은 방사선조사에 의한 물리적 방법과 과산화물을 사용하는 화학적 방법으로 대별할 수 있다. 이와 같이 가교된 PE는 다만 열 특성만이 향상될 뿐더러, 전기적, 기계적 특성에도 변화를 초래하기 때문에 여기에서 실용적 견지에 입각하여 가교포리에티렌의 물성 및 이것을 중심으로한 가교 방법 일반에 대한 개요를 소개하고저 한다.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.179-186
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• 2013

Far-infrared radiation therapies are becoming more popular for blood circulation disorders, cardiovascular disease, skin diseases, inhibit cancer cell, etc replacing conventional operations. In this research, thermal characteristics of heating part in panel radiators, which is effective on the blood circulation disorders were experimentally analyzed. The heating line supplies heat energy to insulation coatings with heat flux of $150mW/m^2$ in normal status and as a result the coatings reached 20% of the heating line temperature. In other words, the insulation itself could increase surface temperature of heating plates by 20% and raise thermal time constant promote blood circulation effect. We also found that space arrangement of the heating lines was an important factor in designing heating parts and both coefficient of heat conduction and density of the heating plate should be also considered for superimpose of thermal diffusion.

• Fire Science and Engineering
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• v.18 no.3
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• pp.45-50
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• 2004

Thermal degradation of PVC which used for insulator of 600V vinyl insulated wire has been studied by thermo gravimetry analysis and accelerated thermal aging test. The activation energy using thermo gravimetry analysis was determined by the kinetic methods, such as Kissinger and Flynn-Wall-Ozawa. The activation energy was determined to from 89.29 kJ/mol to 111.39 kJ/mol in 600V PVC insulated wire and from 97.80 kJ/mol to 119.25 kJ/mol in 600v heat-resistant PVC insulated wire. And also, the activation energy through a long-term thermal aging test was calculated by using Arrhenius equation In the low temperature of 8$0^{\circ}C$, 9$0^{\circ}C$, 10$0^{\circ}C$. The results showed that 600V PVC insulated wire was 92.16 kJ/mol, and 600v heat-resistant PVC insulated wire was 97.52 kJ/mol. Consequently, the activation energy of 600V heat-resistant PVC insulated wire is larger than 600V PVC insulated wire. Therefore, it can be predicted that 600V heat-resistant PVC insulated wire has a long-term stability relatively.

• Journal of the KSME
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• v.19 no.2
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• pp.98-105
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• 1979

이상의 고압중스트레인 측정실험으로부터 다음과 같은 결론을 얻었다. (1) 고압중에서 스트레인을 측정할 경우, 압력효과스트레인이 생기므로 스트레인의 지시치를 보정할 필요가 있다. (2) 고압 효과스트레인은 같은 종류의 게이지에 있어서도 흩어짐이 있으나 흩어짐의 폭은 압력효과스트 레인의 값보다 작다. 특히 300 기압이상에서는 브릿지의 평형을 취해가지고 측정하며는 이 흩 어짐은 한결 작아진다. (3) 고압수중에서 측정 할 경우, 대후론, 시리콘고무, 이중피복선을 도선 으로 하여 사용하고, 게이지의 부분은 시리콘고무코우팅을 되도록 두껍게 하며는 3,000 기압 정 도까지의 수압중에서도 절연저하를 초래하지 안고, 스트레인측정을 할 수가 있다. (4) 상기의 절연방법은 도선인출부에도 적용할 수 있다. (5) 원통형 하우징 모형의 내외면의 스트레인를 측 정한 결과, 유한요소법해석결과의 타당성을 확인 할 수가 있었다. 본실험은 1974년도 일본통산 성공업기술원에서 위탁받아 동지종합연구소에서, [대식도 원읍조작해저석유굴삭장치의 개발]에 관한 연구성과의 일부와 Waterloo 대학의 G.S. Kular 교수연구실의 연구결과임을 밝혔다.