• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.1-6
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• 1998

Our studies diagnose insulation degradation using the method of PD system. In analysis method of degradation, we make use of degradation information that analyzed the phase angle - PD pulse amplitude - degradation time( $\Phi$- PDA - t) pattern and phase angle- PD pulse number - degradation time( $\Phi$- PDN - t) pattern using statistical operators such as skewness(S), kurtosis(K). Secondly using statically operator such as the center of gravity (G), the gradient of the discharge distribution(C), we have analyzed for the prediction of life which we can be obtained the time, occurred of many pulse of small discharge amplitude.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2005.05a
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• pp.232-238
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• 2005

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1780-1785
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• 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss($tan{\delta}$) values of degradation of the cable(joint, knife, needle) at $U_0$ were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF $tan{\delta}$ diagnosis for fault are measured and analyzed. The $tan{\delta}$ values at $U_0$ were "further study advised" or "action required".

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.48-55
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• 2012

Degradation of performance and life time of a functional material or device thereof is induced, to a great extent, by mass transfer in the material that is driven by various thermodynamic forces imposed intentionally or accidentally during its operation or service. The forces are any gradient of intensive thermodynamic variables, component chemical potentials, electrical potential, temperature, stresses, and the like. This paper reviews electric-field induced degradation phenomena in ionic solid compounds including insulation resistance degradation, crystal shift, microstructural alterations, compositional unmixing, and compound decomposition. Their inner workings are also discussed qualitatively.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.372-378
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• 2018

Life management technology is required as the failure risk of aged power transformers increases. Asset management technology is developed to evaluate the remaining life, establish the replacement strategies, and decide the optimal investment based on the reliability and economy of power transformers. The remaining life assessment uses data such as installation, operation, maintenance, refurbishment, and failure of power transformers. The optimal investment also uses data such as maintenance, outage, and social costs. To develop the asset management system for power transformers, determining the degradation parameters related to the aging of power transformers and evaluating the condition of power transformers using these parameters are important. In this study, since 1983, 110,000 Dissolved Gas Analysis (DGA) data have been analyzed to determine the degradation parameters related to the aging of power transformers. The alarm rates of combustible gases ($H_2$, $C_2H_2$, $C_2H_4$, $CH_4$, and $C_2H_6$), TCG, CO, and $CO_2$ were analyzed. The end of life and failure rate (bathtub curve) of power transformers were also calculated based on the failure data from 1981 to 2014. The DGA gases related to discharge, overheating, and insulation degradation were determined based on alarm and failure rates. $C_2H_2$, $C_2H_6$, and $CO_2$ were discharge, oxidation, and insulation degradation parameters related to the aging of power transformers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.91-100
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• 2013

This research is to measure and analyze the thermal performance of the apartment structure and to evaluate and establish standards of thermal insulation defect in order to make the basic data necessary for determining the degree of the thermal performance degradation and for repairing and reinforcing the exterior wall of the existing apartment. Furthermore, it is to predict the part of occurrence of the thermal bridge and condensation at the apartment building structure. On the other one hand, it is also to analyze the degree of thermal insulation performance according to the standards of thermal insulation and elapsed time, through the analysis by the workability of concrete.

• 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 Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.319-322
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• 2001

The proposed system was composed of pre-processor which was executing binary/high-pass filtering and post-processor which ranged from statistic data to prediction. In post-processor work, step one was filter process of image, step two was image recognition, and step three was destruction degree/time prediction. After these processing, we could predict image of the last destruction timestamp. This research was produced variation value according to growth of tree pattern. This result showed improved correction, when this research was applied image Processing. Pre-processing step of original image had good result binary work after high pass- filter execution. In the case of using partial discharge of the image, our research could predict the last destruction timestamp. By means of experimental data, this Prediction system was acquired ${\pm}$3.2% error range.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1063-1064
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• 2008

Bimodal tram has a carbody made of polymer composite material which is good electrical insulator. As an series hybrid type, Alternating voltage generated from generator coupled with CNG engine are rectified and transformed to variable voltage ranges which are applied to electrical apparatus and ECUs equipped inside of the tram. The failures of electrical insulation between high voltage($400V{\sim}800V$) and low voltage(24V) or between different kind of voltages such as AC and DC may cause some electrical interferences to prevent from operating rightly and other safety problem. This paper have investigated about the degradation factors of the electrical insulation and the earthing method available to bimodal tram, which is effective for preventing the electromagnetic interference coming from the inside or outside of tram but need some detecting measurements of earth leakage through electrical systems.

• Journal of the Korean Society of Safety
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• v.9 no.2
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• pp.12-17
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• 1994

Smoke evolved from burning cellulose insulation treated with boric acid-borax-alum as combustion retardants has been studied using a light absorption method. It has been shown that the quantity of smoke are decreased with the increase of oxygen concentration. Applied fire retardants did not increase smoke generation from investigated cellulose insulation in range of themal degradation without flaming. These same fire retardants increased from in the range of flaming combustion. The results of this work have been analysed using imperical equation, which correlated the smoke density at oxygen content of combustion transition. This equation may be. $\sigma$=$\sigma$$_{T}$ exp｛-7.24$\times$10$^{-7}$ ( $O_2$ $O_{2.T}$)｝Where $O_2$is the concentration of oxygen in the oxidizing gas, and $O_{2.T}$ refers to oxygen concentration of combustion transition.n.n.n.