• Elastomers and Composites
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• v.46 no.1
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• pp.22-28
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• 2011

Various materials are used as electrical barrier materials, such as glass, insulating oil, gas, paper and polymer. These materials shut off electricity from conductor as a barrier and separate as well as support conductor from outside environment while using electrical equipment. Polymers are generally used for cable insulation material. Recently environmental regulation are reinforced and eco-friendly materials are in trend.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.912-917
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• 2010

It was known that oil-filled transformer's life depended on insulating paper which was applied to transformers for insulating of transformer. Therefore when paper was aged, its electrical, mechanical and chemical characteristics were changed. Especially if operating temperature was high, paper was quickly damaged. As cellulose paper which was mainly used for solid insulation of transformers was degraded, the cellulose polymer chains broke down into shorter lengths and gases such as CO, $CO_2$, $CH_4$, $C_2H_4$ and so on were produced from paper. Also by-product known as furan compounds were producted from paper and it were dissolved within insulating oil. In this paper accelerating aging cell was aged during 60 hours at 100, 150, 180 and $200^{\circ}C$, respectively, so evaluating the chemical characteristics of cellulose paper by thermal. An it were performed analysis such as tensile strength(TS), dissolved gas analysis(DGA) and high performance liquid chromatography(HPLC). Also for analyzing of correlation between insulating degradation characteristics, it was performed linear regression method as statistical treatment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.125-132
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• 2001

This paper proposes integrated safety diagnosis system of motor used in a ship. It carried out the safety diagnosis for insulation-resistor and current. The motor exposed to sea breeze and oil all the time is able to have problems as a over-current, reduction of the insulation-resistor and so on. These problems impact on the safety navigation, and occur a heavy casualties and loss of property. The proposed system is able to sense error of the motor before a accident occur, by verifying and controlling value of the insulation-resistor and current in working area or control room. The validity of the proposed system is verified through experiment results on the 3-Phase induction motor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.474-478
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• 2001

This paper proposes integrated diagnosis system of motor for a ship. It carried out the safety diagnosis for insulation-resistor and current. The motor exposed to sea breeze and oil all the time is able to have problems as a over-current, reduction of the insulation-resistor and so on. These problems impact on the safety navigation, and occur a heavy casualties and loss of property. The proposed system is designed to verify continuous values of the insulation-resistor and current, and transfer them to a remote control room. The validity of the proposed system is verified through experiments on the 3-phase induction motor.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1865-1867
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• 2002

In this paper, frequency spectra of AE signals detected from respective the insulation deterioration were analysed to under ac high-voltage application using epoxy resin sample and insulation oil. Also, frequency spectra of AE signals generated from the load currents in the actual operating transformer of 500[kVA] under distribution system of 22.9[kVJ] were also analysed to distinguish the AE signals due to void discharges from the magnetic circuit noises in transformer. As the experimental results, we could distinguish the AE signals whether those signals were caused due to the void discharges or due to the magnetic circuit noises by analyzing the frequency spectrum of AE signals.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1274-1279
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• 2011

The purpose of this paper is to present the manufacturing defect and damage pattern of a 3 phase 22.9/3.3kV oil immersed transformer, as well as to present an objective basis for the prevention of a similar accident and to secure data for the settlement of PL related disputes. It was found that in order to prevent the occurrence of accidents to transformers, insulating oil analysis, thermal image measurement, and corona discharge diagnosis, etc., were performed by establishing relevant regulation. The result of analysis performed on the external appearance of a transformer to which an accident occurred, the internal insulation resistance and protection system, etc., showed that most of the analysis items were judged to be acceptable. However, it was found that the insulation characteristics between the primary winding and the enclosure, those between the ground and the secondary winding, and those between the primary and secondary windings were inappropriate due to an insulating oil leak caused by damage to the pressure relief valve. From the analysis of the acidity values measured over the past 5 years, it is thought that an increase in carbon dioxide (CO2) caused an increase in the temperature inside the transformer and the increase in the ethylene gas increased the possibility of ignition. Even though 17 years have passed since the transformer was installed, it was found that the system's design, manufacture, maintenance and management have been performed well and the insulating paper was in good condition, and that there was no trace of public access or vandalism. However, in the case of transformers to which accidents have occurred, a melted area between the upper and the intermediate bobbins of the W-phase secondary winding as well as between its intermediate and lower bobbins. It can be seen that a V-pattern was formed at the carbonized area of the transformer and that the depth of the carbonization is deeper at the upper side than the lower side. In addition, it was found that physical bending and deformation occurred inside the secondary winding due to non-uniform pressure while performing transformer winding work. Therefore, since it is obvious that the accident occurred due to a manufacturing defect (winding work defect), it is thought that the manufacturer of the transformer is responsible for the accident and that it is lawful for the manufacture to investigate and prove the concrete cause of the accident according to the Product Liability Law (PLL).

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1202-1204
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• 1995

In this paper, We investigated a charge elimination by using a needle electrode in order to prevent the electrification phenomena of insulating oil flowing by force at the internal transformer. In our experiment, We used Acryle and Teflon as the material of charge reducer and measured each of their streaming current and needle electrode current. As a result of experiment, We can explain that the current of needle electrode increase in proportion to insulation of charge reducer.

• Journal of Power System Engineering
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• v.4 no.3
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• pp.55-61
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• 2000

In this study, a new design of an one-body type of an unbalanced-fixed- displacement type vane pump combined with an induction type electric motor was suggested. By the application of the new design scheme, it was possible to reduce the number of parts of the pump system and to cut down the volume of power package than that of already-used products. The case in this study enabled efficient heat transfer and electricity insulation of hydraulic fluid. Thus oil moves through the inside of the package for cooling and returns to the reservoir. Because of this design, it was difficult to measure the shaft-input torque. Therefore the package overall efficiency in the paper was evaluated with a ratio of hydraulic power and electric power.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.241-245
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• 1988

This paper reports the experiments regarding to diagnosis techniques for power transformers by measuring dissipation factor and moisture contents of mineral oils. Thermal aging environments of mineral oils were varied by the specially designed systems. Thermal aging of elevated temperature of $90^{\circ}C$ was performed for about 240 and 460 hours, respectively. Dissipation factor, permittivity, and water content were measured. Our test samples were not exposed to air. Dissipation factor increased while permittivity did not change. The level of dissipation factor determining the insulating quality of mineral oil was compared with the previous results of resistivity and several correction factor.

• 전기의세계
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• v.34 no.8
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• pp.476-488
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• 1985

전기공학분야의 여러다른 부분과 같이 전력케이블 분야에서도 수많은 연구와 아울러 특히 19세기후반에 전력케이블의 제작에 성공한 것은 20세기에 들어와서 케이블과 이에 관련된 모든 기술이 빠른 속도로 발달하게된 주원동력이 되었다고 보아도 과언은 아니다. 비록 19세기 후반에 고무(rubber)를 사용하여 케이블 절연 하였지만, 그이후 약 70여년이상을 Impergnated paper(오일복합수지(oil compound resin)나 오일(oil)을 종이에 스며들게한 후 그 종이를 절연재료로 이용함)를 전력케이블 절연재료로 많이 사용하여 왔다. 아울러 OF cable의 제조기술도 향상되어 현재 매우 높은 전압과 상당한 전력용량를 충족시키는 전력케이블로서 발달을 계속하고 있다. 1960년대에 들어서서 extruded polymer material 이 전력케이블의 절연재료로 쓰이게 되었는데 현저하게 주로 쓰이는 재료로 폴리에틸렌인대, 그대로 순수한 상태로 또는 어떤 처리를 하여 쓰기도 한다. 그러나 EPR(ethylene propylene rubber)도 역시 개발중에 있다. Extruded synthetic insulation을 사용한 케이블은 현재 모든 필요한 전류와 전압을 망라하여 널리 쓰이고 있으며 다른재료를 사용한 케이블 보다 설치하기에 쉽고 사용법이 비교적 간단하고, 또한 전력망(network)에서의 신뢰서이도 높은 것으로 나타나 매우 만족스런 재료로 인정받고 있다.