• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.81-88
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• 1996

In order to investigate the electrical properties of transformer oils for large power, the characteristics of AC and Impulse breakdown in gap length of 1.0~2.5mm and that of volume resistivity were researched in temperature range of 20~$100^{\circ}C$. An geometrical capacitance of electrode with coaxial cylindrical shape for measuring the volume resistivity was 16pF, and highmegohm meter with model no. VMG-1000 was used, and also the applied voltage were DC 100, 250 and 500V. In the dependance of breakdown characteristics due to electrode gap length, it was confirmed that breakdown voltage was nearly uniform by volume effect according to the increase of gap. In the characteristics for AC breakdown, the dielectric strength was increased to $90^{\circ}C$ but decreased over $90^{\circ}C$, and also in case of impulse breakdown, it was increased to 7$0^{\circ}C$ and at dated $70^{\circ}C$ over in temperature range. The calculated mobility of oils in the characteristics for impulse breakdown were about $10^{-5}$~$10^{-4}cm^2/V{\cdot}S$, and the value of volume resistivity was almost invariable in low temperature range, regardless of voltage by the stable thermal properties, and it indicated a peak at $50^{\circ}C$ and had a sudden change to decrease over that temperature, and also the value of volume resistivity in 250V/mm at $80^{\circ}C$ is suitable for the International electrical standards, it was confirmed.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.209-211
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• 1996

The dielectric breakdown characteristics of DGEBA/MDA/SN system filled with $Al_2O_3$ under AC high electric field were investigated. As the filler content increased, the dielectric breakdown strength increased, but decreased at higher filler content than 5 phr. The probability of defects such as air bubbles, peel between filler and epoxy resin insulator, etc. increase proportionally to filler contents. Fillers blockade the treeing growth and relax the electric field at the tip of electrical tree and the treeing propagation rate decreases so that the strength showed higher strength at lower filler content than 5 phr.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1838-1841
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• 2004

This test was performed to assess the correlation between insulation diagnostic tests and breakdown voltage strength of the stator winding of 6.6kV class induction motor in insulation deterioration condition which have been in service for 5 years after being installed in 1998. The insulation diagnostic tests include resistance, polarization index(P.I), dissipation factor(${\triangle}tan{\delta}$), maximum partial discharges(Qmax) and AC breakdown test. we evaluated the correlation between insulation diagnostic test and AC breakdown test for stator winding of high voltage induction motor.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.46-49
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• 2004

This test was performed to assess the correlation between insulation diagnostic tests and breakdown voltage strength of the stator winding of 6.6kV class induction motor in insulation deterioration condition which have been in service for 5 years after being installed in 1998. The insulation diagnostic tests include resistance, polarization index(P.I), dissipation factor(${\Delta}tan{\delta}$). maximum partial discharges(Qmax) and AC breakdown test. we evaluated the correlation between insulation diagnostic test and AC breakdown test for stator winding of high voltage induction motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.190-195
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• 2009

This paper introduces experimental investigates of an electrical accident of the distributing cable termination with simulated a shoddy construction. We prepared two termination kites, one is built-in type, the other is heat contraction type. Also, we manufactured cable termination that have simulated defect by badness construction and investigated their insulation characteristics such as ac (35[kV], 1[min]) and impulse (95[kV], $1.2{\times}50[{\mu}s]$) withstand test. The influence of defects such as thickness decrease, the gap between stress-con of housing and semiconductor and heating time on insulating properties of the termination have been studied. The thickness decrease of an insulator decreases ac breakdown strength suddenly and the breakdown traces of the insulator that is damaged by knife displayed elliptic shape. The gap of between stress-con and semiconductor deteriorates dielectric strength of insulator seriously. In heat contraction type, the ac breakdown voltage became low when the heating time is short.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.2
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• pp.77-83
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• 1991

In this study the investigation were carried out on short-term breakdown characteristics of the compound material dependent on change of filler quantity, ambient temperature(room temperature~[$190[^{\circ}C$]) and kinds of voltage sources for the compound materials of Bisphenol- A epoxy resins filled with $SiO_2$ particles. As the results, obtained the dielectric breakdown strength generally decrease as increasing the quantity of filler and the distance, spacing of each's particles, decrease as increasing the quantity of filler, when the distance is less than [$7.5\mu\textrm{m}$], dielectric breakdown strength is nearly constant. In the case on AC voltage dielectric strength of filled epoxy resins is stronger than nonfilled epoxy resins on temperature region more than $130[^{\circ}C$].

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.113-114
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• 2008

The purpose of this paper is to analyze AC Breakdown of solid/air composite insulation depending on the thickness and the pressure of dry air for eco-friendly insulation. SF6 gas has been widely used in electric equipment as gas insulation because of high dielectric strength and arc extinguishing performance. However, because SF6 gas is one of the green house effect gases, alternative insulation such as SF6 mixture, extremely low temperature gas, vacuum, liquid and solid insulating are being investigated.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.263-266
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• 2007

In this paper approves (AC and DC) high voltage by experimental GIS(Gas Insulated Switchgear) chamber and (AC and DC) power source to study breakdown characteristics by pressure(P) change and change of electrode distance(d) at (AC and DC) high voltage of Imitation I-Air, $N_2$ : $O_2$ = 79(%) : 21[%]) to alternate $SF_6$ and achieved research. Gave P change of I-Air to study I-Air's Dielectric Strength using uniform and non-uniform fields(sphere-sphere and Needle-Plane electrode) and studied relations dielectric strength($V_D$) by each P different d.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.941-943
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• 1999

In this paper, the AC breakdown properties to investigate the electrical properties of gate oxide layer in MOSFET was studied. 5 inch arsenic epi-wafer is selected as an experimental specimen, the power MOSFET of a general MOS structure was made. In order to analyze the physical properties of the specimen, the SIMS(secondary ion mass spectroscopy) was used. As the experimental condition, the experiment al of the AC breakdown characteristics was performed when the thickness of gate oxide layer is $600[\AA]$ and $800[\AA]$, the resistivity is $1.2[\Omega{\cdot}cm]$, $1.5[\Omega{\cdot}cm]$ and $1.8[\Omega{\cdot}cm]$, and the diffusion time is 110[min] and 150[min] in temperature $30[^{\circ}C]{\sim}100[^{\circ}C]$. From the analysis result of the SIMS spectrum, it is confirmed that the dielectric strength is decreased by contribution of the impurities ad dition as increasing in thickness of the gate oxide layer in MOSFET.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.65-68
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• 2003

In this paper, we researched breakdown characteristics of paper/liquid nitrogen composite insulation system for application of a high temperature superconducting cable. And, we have studied the AC breakdown performance of paper/ice composite insulating system immersed in liquid nitrogen. The electric strength in this paper/ice composite system is higher than that of paper/liquid nitrogen system. Furthermore this system shows a self-healing type breakdown behavior. Among the many kinds of liquid to be immersed and frozen to the ice, deionized water gives the highest electric breakdown strength. The paper/ice composite insulation system is thought to be one of good candidate for the electrical insulating system at cryogenic temperature.