• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.301-306
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• 2014

Recently in accordance with the rapid development of the industrial society, the accidents caused by dielectric breakdown have been increasing in power grid. It is important to prevent the dielectric breakdown of a high voltage apparatus to reduce the damage from electrical hazards. To establish an electrically reliable database of insulation design criteria for high voltage apparatus, a study on dielectric characteristics test is indispensable. In this study, dielectric characteristics according to field utilization factors (${\xi}$) which are represented as the ratio of mean electric field to maximum electric field are investigated. the dielectric breakdown experiments by using several kinds of electrode systems made with stainless steel are performed by AC breakdown voltage under air-insulation. Also, the experimental results are analyzed by the Weibull distribution. As a result, it is found that the dielectric characteristics of air-insulation are determined by ${\xi}$ as well as arrangement of electrode systems. It is considered that the results of this study would be applicable to designing the air-insulated high voltage apparatuses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.164-167
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• 1997

A series of interpenetrating polymer networks(IPN) based on Epoxy, MA and PU were synthesized in order to improve withstand voltage properties of Epoxy resin. Dielectric breakdown characteristics are investigated for six types of specimens. As a result, it was found that impulse voltage dielectric breakdown characteristic of SIN specimen was the most excellent. It was also found that SIN specimens were stronger than anything else in scanning electron microscopy. On the other hand, as a result of consideration of dielectric breakdown strength change according to adding fi1ter, it was confirmed that the decrease of dielectric breakdown strength are controlled slightly by IPN method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.804-808
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• 2010

In this paper, we studied the dielectric breakdown voltage characteristics by the AC withstand voltage test on using green insulation dry air instead of $SF_6$ insulation gas used in the GIB (gas insulated bus) of 362 kV GIS (gas insulated switchgear). The AC withstand voltage test applied to the standard KEPCO's 362 kV GIB with dry air insulation, and the equivalence of dielectric breakdown voltage for dry air and $SF_6$ gas were examined, and the empirical formulas of dielectric breakdown voltage for dry air were calculated, and the criterion of AC withstand voltage test for dry air insulation was derived. Using the criterion, dry air can be used instead of $SF_6$ gas for 362 kV GIB in the factory acceptance test was confirmed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1992.11a
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• pp.37-40
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• 1992

This paper examined the existance behavior of charged particles by measuring polarity inversion current Thermal Stimulate Current (TSC) and analysed appearance mechanism of polarity inversion current Peak and Also investigated relation between ionic space charge format ion and dielectric breakdown by measuring D.C breakdown impulse breakdown D.C - impulse superposition as a sample of FET. As a result. lie found that dielectric breakdown is likely to happen due to ionic space charge at the transient state when applied polarity inversion voltage and that charged partion of TSE Peak at the high temperature was the same as that of polarity inversion current. Also there was no effect on ionic space charge about the dielectric breakdown in stationary state when applied D.C voltage.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.380-382
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• 1989

Dielectric breakdown strength (Eb) of thin Poly(Vinylidene Fluoride ; PVDF) film is studied in the temperature range between 4.2 K and 400 K. The results of this study can be summerized as follows. 1) Temperature dependence of dielectric breakdown strength (Eb) can be devided into high and low temperature regions. The critical temperature (Tc) at which two regions are devided depends on applied voltage. 2) Dielectric breakdown strength (Eb) by pulse voltage is higher than that by DC voltage. Especially this difference is remarkable at low temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.605-608
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• 2001

With the intention of investigating the breakdown properties of oil-immersed transformer oils in temperature range of 20∼100[$^{\circ}C$], we are made researches AC breakdown in the gap of 500∼2,500[$\mu\textrm{m}$]. The classification for the physical properties of oil for oil-immersed transformer by FTH and $^1$H-NMR experiments was confirmed to type of mineral oils. As the dependance of breakdown properties due to electrode gap length variation, breakdown voltage was found increasing according to the increase of gap, while dielectric strength was decreasing. As a result the characteristics for AC breakdown, It goes to prove that the breakdown voltage was increased to 90[$^{\circ}C$] but decreased over 90[$^{\circ}C$] in the temperature range. Also, breakdown voltage was found increasing in the increase of gap and the rising of temperature according to Weibull distribution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.2
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• pp.118-123
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• 2007

The purpose of this work was to investigate the design and fabrication process effects on electrical properties in high capacitance multilayer ceramic capacitor (MLCC) with nickel electrode. Dielectric breakdown voltage and insulation resistance value were decreased with increasing stack layer number, but dielectric constant and capacitance were increased. With increasing green sheet thickness, dielectric breakdown voltage, C-V and I-V properties were also increased. The major reasons of the effects were thought to be the defects generated extrinsically during fabrication process and interfacial reactions formed between nickel electrode and dielectric layer. These investigations clearly showed the influence of both green sheet thick ness and stack layer number on the electrical properties in fabricating the MLCC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.48-48
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• 2010

In this paper, we have investigated temperature dependence of dielectric breakdown voltage at epoxy with added nano-filler(MgO), which is used as a filler of epoxy additives for HVDC(high voltage direct current) submarine cable insulating material with high thermal conductivity and restraining tree to improve electrical properties of epoxy resin in high temperature region. In order to find dispersion of the specimen, the cross sectional area of nano-composite material is observed by using the SEM(Scanning Electron Microscope) and it is conformed that each specimen is evenly distributed without the cohesion. As a result, it is confirmed that the strength of breakdown of all specimen at 50 [$^{\circ}C$] decreased more than that of the dielectric breakdown strength at room temperature. When temperature increases from 50 [$^{\circ}C$] to 100 [$^{\circ}C$], we have confirmed that breakdown strength of virgin specimen decreases, but specimens with added MgO show constant dielectric breakdown strength.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.4
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• pp.659-665
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• 2017

Power semiconductor devices required the low on-resistance and high breakdown voltage. Wide band-gap materials opened a new technology of the power devices which promised a thin drift layer at an identical breakdown voltage. The diamond had the wide band-gap of 5.5 eV which induced the low power loss, high breakdown capability, low intrinsic carrier generation, and high operation temperature. We investigated the p-type pseudo-vertical diamond Schottky barrier diodes using a numerical simulation. The impact ionization rate was material to calculating the breakdown voltage. We revised the impact ionization rate of the diamond for adjusting the parallel-plane breakdown field at 10 MV/cm. Effects of the field plate on the breakdown voltage was also analyzed. A conventional diamond Schottky barrier diode without field plate exhibited the high forward current of 0.52 A/mm and low on-resistance of $1.71{\Omega}-mm$ at the forward voltage of 2 V. The simulated breakdown field of the conventional device was 13.3 MV/cm. The breakdown voltage of the conventional device and proposed devices with the $SiO_2$ passivation layer, anode field plate (AFP), and cathode field plate (CFP) was 680, 810, 810, and 1020 V, respectively. The AFP cannot alleviate the concentration of the electric field at the cathode edge. The CFP increased the breakdown voltage with evidences of the electric field and potential. However, we should consider the dielectric breakdown because the ideal breakdown field of the diamond is higher than that of the $SiO_2$, which is widely used as the passivation layer. The real breakdown voltage of the device with CFP decreased from 1020 to 565 V due to the dielectric breakdown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.245-251
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• 2008

Although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of $SF_6/CF_4$ mixtures in non-uniform field was performed. The experiments were carried out under AC voltage and standard lightning impulse(SLI) voltage. Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltages and standard lighting impulse voltage was applied in a needle-plane. The needle-plane electrode whose gap distance was 3 mm were used in a test chamber. $SF_6/CF_4$ mixtures contained from 0 to 100% $SF_6$ and the experimental gas pressure ranged from 0.1 to 0.5 MPa. The breakdown characteristics of $SF_6/CF_4$ mixtures in non-uniform field may be influenced by defects like needle-shaped protrusions. In case of slowly rising SLI voltage and AC voltage it is enhanced by corona-stabilization. This phenomena caused by the ion drift during streamer development and the resulting space-charge is investigated. In non-uniform field under negative SLI voltage the breakdown voltage was increase linearly but under positive SLI voltage the breakdown voltage increase non-linearly. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at AC voltage. $SF_6/CF_4$ mixture has good dielectric strength and arc-extinguishing properties than pure SF6. This paper presents experimental results on breakdown characteristics for various mixtures of $SF_6/CF_4$ at practical pressures. We could make an environment friendly gas insulation material with maintaining dielectric strength by combing $SF_6\;and\;CF_4$ which generates a lower lever of the global warming effect.