• 전기의세계
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• v.27 no.6
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• pp.76-83
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• 1978

This paper reveals the results of fundamental experiments with the breakdown strength- and treeing phenomena, by A.C voltage and impulse voltage, of cross-linked polyethylene insulator, respectively compared in each case of the various specimens; nonvoid, air void, water void, oil void and oil impregnated one, all articially made. In this research, the V-t and V-n characteristics are investigated by means of the Weibull distribution and are analysed the characteristics of fatigue breakdown caused by the A.C and impulse voltage. Based on numerous tests, treeing effect and treeing breakdown mechanism is investigated through microscopic photographs taken to clarify the shapes of each tree and treeing breakdown phenomena.

• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.324-328
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• 2013

An alternating current (AC) electrical treeing phenomena in an epoxy system with low chlorine BDGE (1,4-butanediol diglycidyl ether) was studied in a needle-plate electrode arrangement. To measure the treeing propagation rate and breakdown time, a constant AC of 10 kV with three different electric field frequencies (60, 500, and 1,000 Hz) was applied to the needle-plate electrode specimen at $130^{\circ}C$ in aninsulating oil bath. The treeing propagation rate of the DGEBA/high-chlorine BDGE system was higher than that of the DGEBA/low-chlorine BDGE system and the breakdown time of the system with high-chlorine BDGE was lower than that of the system with low-chlorine BDGE. These results implied that chlorine had a negative effect on the electrical insulation property of the epoxy system. As the electric field frequency increased, the treeing propagation rate increased and the breakdown time decreased.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.8
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• pp.455-461
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• 2000

The inhibiting effects of electrical treeing and insulation properties of LDPE contained with treeing inhibitors was studied under radiation environment. Barbituric acid and its derivatives were selected as treeing inhibitors. The inception voltage and growth of tree, AC breakdown strength, volume resistivity, high frequency capacitance, and dissipation factor were observed as a function of dose(up to 1000 kGy). And also, measurements of thermo-luminescence(TL), and gel content were carried out. Crosslinked low density polyethylene(XLPE) contained with treeing inhibitors shows better insulation characteristics such as electrical tree propagation, AC breakdown strength, and volume resistivity than those of pure LDPE. The most effective treeing inhibitor was found on the barbituric acid contained XLPE.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.6
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• pp.406-413
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• 1988

This paper is to investigate relationships between tree inception voltage, tree extension or treeing breakdown voltage and physical characteristics changing as parameter of the post-cured conditions of thermo-setting epoxy resin. According to the results in this paper, the optimal tree inception voltage and treeing breakdown voltage of the samples are obtained for the sample post cured for 15 hours at 100 'C. It can be noticed that these results are closely related with the state of interior molecule coupling and three-dimen sional cross-linked of thermo-setting epoxy resin. And tree inception, tree extension and treeing breakdown of the samples are affected significantly on the post-cured conditions and the cooling method after post-cured of thermo-setting epoxy resin. Moreover, the tree extension by ambient temperature are closely related with softening temperature of thermo-setting epoxy resin.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.122-128
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• 1994

Studies on treeing phenomena have depended on the visual measurement using optical microscope. In the visual measurement, it is difficult to analyze the treeing in real time because voltages are applied discontinuously and impossible to calculate the deterioated area by treeing. Only tree type and length are studied. In this paper, image processing is introduced and voltages are applied continuously. The tree length and area are calculated in real time from tree inception to breakdown. Growing characteristics about tree types are compared for the normalized breakdown time.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2335-2337
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• 1999

In this paper, using AE (Acoustic Emission) sensor the electrical and emitted-sound signals are measured by treeing breakdown in the epoxy resin, and the corresponding frequency spectrum of the AE signals are analyzed. We also examined the relationship between partial discharge magnitude and pulse number of AE signals to diagnose the deterioration of the electrical insulation due to treeing breakdown. From these results, a frequency band of AE signals through treeing breakdown was set to about 230 [kHz], and it appeared that pulse number of AE signal was proportional to partial discharge magnitude.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.193-196
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• 2001

XLPE is occasionally happened to deteriorate cable insulation characteristics. It is happened to do a breakdown state by the degradation of electrical characteristic and electrical breakdown strength. I prepared TR-XLPE (Tree-Retardant XLPE) as adding various additives to prevent its states. Various additives are treeing retardants, anti-oxidants. Treeing retardants three kinds of aromatic compounds as adding each additive. Anti-oxidants use quinone compound and cresol compound as adding each additive. In order to observe each electrical characteristics, I measured breakdown strength, relative dielectric constant$({\varepsilon}_r)$, dielectric loss tangent$(tan{\delta})$. TR-XLPE specimens as adding treeing retardants and anti-oxidants enhance breakdown strength, ${\varepsilon}_r$, $tan{\delta}$ than pure XLPE.

• Transactions on Electrical and Electronic Materials
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• v.14 no.4
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• pp.221-224
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• 2013

Effects of ambient temperature on the ac electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were carried out in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin,, using our ac electric field apparatus. To measure the treeing initiation and propagation, and the breakdown rate, constant alternating current (ac) of 10 kV (60 Hz) was applied to the specimen in a needle-plate electrode arrangement, at $30^{\circ}C$, $90^{\circ}C$ or $130^{\circ}C$ of insulating oil bath. At $30^{\circ}C$, the treeing initiation time and the breakdown time in the epoxy/layered silicate (1 wt%) system were 1.4 times higher than those of the neat epoxy resin. At $90^{\circ}C$ (lower than Tg), electrical treeing was initiated in 55 min, and propagated until 1,390 min at the speed of $0.35{\times}10^{-3}mm/min$, which was 4.4 times higher than that at $30^{\circ}C$; however, there was almost no further treeing propagation after 1,390 min. At $130^{\circ}C$ (higher than Tg), electrical treeing was initiated in 44 min, and propagated until 2,000 min at the speed of $0.96{\times}10^{-3}mm/min$. Typical branch type electrical treeing was obtained from the neat epoxy and epoxy/layered silicate at $30^{\circ}C$, while bush type treeing was observed out from the needle tip at $90^{\circ}C$ and $130^{\circ}C$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1571-1577
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• 2013

Electrical tree structure is one of the most important influencing factors for electrical treeing characteristics in polymers. In this paper, we focused on the structure characteristics of electrical treeing in epoxy resins (original) insulation under different high-frequency voltages (60, 500, 1000Hz). Effects of voltage frequency on the ac electrical treeing phenomena in an epoxy resins were carried out in needle-plate electrode arrangement. To measure the treeing initiation and propagation, and the breakdown rate, constant AC of 10 kV with three different voltage frequencies (60, 500 and 1,000 Hz) was applied to the specimen in needle-plate electrode specimen at $30^{\circ}C$ of insulating oil bath. At 60 Hz, the treeing initiation time was 360 min and the propagation rate was $6.85{\times}10^{-4}mm/min$, and the morphology was dense branch type. As the voltage frequency increased, the treeing initiation time decreased and the propagation rate increased. At 1,000 Hz, the treeing initiation time was 0 min and the propagation rate was $7.81{\times}10^{-2}mm/min$, and the morphology was dense bush type.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.425-428
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• 1996

Treeing deterioration which is one of the main cause of breakdown in insulating materials is affected by temperature, applied voltage and frequency. In this study, GN was introduced to improve impact strength of DGEBA/MDA system and the temperature dependence of AC treeing deterioration in this system was investigated. Dielectric breakdown strength decreased with the increment of temperature. As temperature increased, the growth rate of tree Increased.