• 전기의세계
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• v.20 no.4
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• pp.5-11
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• 1971

This is a study on the insulation methods of home appliances and wiring devices proper to the new electric distribution system, primary side is 22.9/13.2KV, 3 phase 4 wire multigrounding system and secondary side is 380/220V, 3 phase 4 wire common neutral system. 1800V is determined as the electrical insulation voltage of the functional insulation because the abnormal voltage rise of the neutral line is 1300V. In the case of the functional insulation faults, the following safety methods will be suggested to protect the accidental faults: (a) class I appliance (accessible metal part is earthed), (b) class II appliance (doublly insulated), (c) class III appliance (operates at low voltage source). The mechanisms of the wiring devices are not improved to guarantee for the harmful electric shock but also the electrical insulation voltage is rised to 2000V.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.204-205
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• 2015

Exterior insulation board in cast-in-place concrete form system could reduce construction period and improve quality in apartment construction. However, the method is progressed with insulation and concrete frame works at the same time, then risk is increased in duration control and quality management. Therefore, this paper analyzed risk factors through FMEA method. We found that the key risk factors delaying schedule was insulation material that soaked in the rain and quality defects on the insulation material joint. Based on this research, the risk management approach should be developed for improvement of method activation.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1002-1008
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• 2014

This paper describes insulation design and its reliability evaluation of ${\pm}80kV$ HVDC XLPE cable. Recently, the construction of HVDC transmission system, which is combined overhead line with underground cable, has been completed. This system is installed with existing 154 kV AC transmission line on the same tower. In this paper, the lightning transient analysis is firstly reviewed for selection of basic impulse insulation level and nominal insulation thickness. Then the electrical performance tests including load cycle test and superimposed impulse test based on CIGRE TB 496 are performed to evaluate the reliability of newly designed HVDC cable. There is no breakdown for ${\pm}80kV$ HVDC XLPE cable during electrical performance test. Finally, this system is installed in Jeju island based on successful electrical performance test (Type test). After installation tests are also successfully completed.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1012-1018
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• 2006

In this study, the insulation performance of thermal insulation materials such as glass wool, polyetylene and flexible lastomeric foam according to water vapor permeance was estimated by using experimental correlation equation. The results showed the conductivity increment of flexible lastomeric foam which has very low-permeability (${\le}0.15[ng/{\cdot}s{\cdot}Pa]\;or\;{\mu}{\ge}1,000$) is about 50% lower than that of glass wool with the lapse of ten years. The conclusion is that moisture inevitably accumulated in permeable Insulations reduces insulation performance and also accelerates surface condensation in the case of cold water system.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.407-418
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• 2011

Recently energy management measures at the political level, for the purpose of reducing energy consumption in the building sector, are being actively introduced. As a practical method, the exterior insulation method, which is proven to effective in reducing the energy loss through walls, has been favored. In this study, detailed implementations are suggested to activate exterior insulation system which can improve the housing insulation performance. The newly designed Gang-form system with hanging scaffolding was suggested to revamp constructability for finishing outer wall. The research results are based on a multifaceted analysis of the current problems of exterior insulation systems, and on recommendations proposed by exterior insulation experts in the Charrette discussion. The study has indicates that the customized TACT schedule considering the site condition has shortened the construction period to 5 months from 7.5 months. Through utilizing the suggestions of this study, the prevalence of exterior insulation systems is expected to become widespread.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.577-583
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• 2013

We have analyzed influence of potential rise in negative bus, which caused by decrease of power feeding line insulation, upon protecting method of DC ground protection device which detecting potential rise between negative bus and ground in order to detect ground fault in the rubber wheel system. For this purpose, we proposed negative potential equation between negative bus and ground and calculated negative potential according to system condition changes by estimating power feeding line insulation changes in steel wheel system and rubber wheel system, and equalizing DC power feeding system when ground fault occurred. Also, in order to estimate negative potential of real system, we modeled the rubber wheel system, and simulated normal status, grounding fault occurrence and power feeding line insulation changes. In normal status, negative potential did not rise significantly regardless of vehicle operation. When ground fault occurred, negative potential rose up over 300V regardless of fault resistance. However, we also observed that negative potential rose when power feeding line insulation dropped down under $1M{\Omega}$. In conclusion, our result shows that in case of rubber wheel system unlike steel wheel system, relay will be prevented maloperation and insulation status observation can be ensured when ground over voltage relay will be set 200V ~ 300V.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.469-475
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• 2009

Accident dangerousness of domestic hydro power generators which are operated in Korea is on the increase because of use at the long term. On this, the Off-line diagnosis techniques developed to the On-line by continued domestic technical development since 2000. Especially, On-line insulation diagnosis of domestic hydro power generator is possible by localization of partial electric discharge sensor and On-line insulation diagnosis system. This paper shows the diagnosis result that is applied localized Ceramic Coupler and PDMS-HG(Partial Discharge Monitoring System for Hydro Generator) at four Chung-ju hydro Generator used for 25 years. Particularly, the confidence of insulation diagnosis is improved by using high frequency filter and sampling the partial discharge signals which occur in site. For reviewing the confidence of On-Line insulation diagnosis system, we measured the outside noises and partial discharge signals during practical operation by using the partial discharge diagnosis system of the Full A/D process. And we reviewed the confidence of the On-Line insulation diagnosis system by comparing and analyzing these data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.230-233
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• 1999

Because Insulation material is play an important part for normal work of electricity equipment, the study is advanced, but as the voltage of electricity system is raising, we required that new lnsulation material. They have excellent specific against high stress, namely the study of insulation increase and prevention diagnosis of insulation degradation of Epoxy or XLPE and so on. In this thesis. I utilize image processing technique for effective inspection of insulation material degradation.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1512-1519
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• 2013

Oil-impregnated paper is a major type of insulation used in oil-filled converter transformers for both traditional and new energy systems. This paper presents and analyzes the results of the experiment conducted on the electrical aging of oil-impregnated paper under AC-DC combined voltages using the pulsed electro-acoustic (PEA) technique. The formation and dynamics of space charge affected the performance of insulation material. The electrical aged oil-paper insulation was obtained through electrical aged experiments under the voltages. Based on the PEA technique, measurements were carried out when the oil-paper insulation system was subjected to different stressing and aging times. The space charge dynamics in the bulk of the oil-paper insulation system with different aging times were measured and analyzed. Characteristic parameters such as the total charge injection amount, the total charges of fast moving and slow moving, and the distortion factor of electric field were calculated and discussed. Results show that the longer electrical aging time, the more charges trapped in the bulk of aging sample. It leads to larger distortion factor of electric field in the bulk of aging samples and accelerate degradation of oil-paper insulation under AC-DC combined voltages.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1025-1027
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• 1999

Recently, many researches on a diagnosis of stator winding insulation of large generators are reported. They mostly utilize a trend analysis of Partial Discharge (PD). In this paper, a novel on-line monitoring system for an insulation diagnosis is proposed. This system obtains the parameters such as Maximum Partial Discharge Magnitude (QM), Normalized Quantity Number (NQN) and Dynamic Stagnation Voltage (DSV) by continuous on-line monitoring of winding insulation. It is capable of diagnosing the insulation condition by analyzing the trend of PD and utilizing the database built by the system.