• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.605-608
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• 1993

Breakdown characteristics of a small rod-to-rod microairgap has been studied for obtain an optimum breakdown voltage and an airgap spacing to be used as an emission control means by the electrical arc-burning unburnt carbon particulates exhausted from a power station burner. It is found that the breakdown voltage at the rod-to-rod airgap spacing in the rang of $1{\sim}100{\mu}m$ decreased with decrease in the rod-to-rod airgap spacing. And there were no minimum breakdown voltage on a $V_b$-Pd characteristics which is known as the minimum voltage in Paschen's law in air atmosphere. Breakdown voltages of the airgap at the constant airgap spacing were $V_{b-dc}>V_{b-ac}>V_{b-pulse}$, and it was lowest for the pulse voltage applied. As a result, it is found that a pulse power was one of effective power compared with dc or ac to be used as such an unburnt carbon particulate emission control means and the airgap spacing became to several tens ${\mu}m$, then the breakdown voltages were down to several handreds voltages.

• Journal of Korean Vacuum Science & Technology
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• v.4 no.1
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• pp.33-37
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• 2000

Properties of electrical discharge in flames and influence of plasma electrons on gas neutrals are investigated by making use of the ionization cross section of air. Frames have three distinctive features. They are hot, emit light and are weakly ionized. We investigate influence of these three characteristics of flames on the electrical breakdown. It is found that the breakdown electric field in flames is inversely proportional to the flame temperature T$\_$g/, thereby easily generating plasmas in flames. A swarm of low-energy electrons in flames would allow a significant population of electronically excited states of flame molecules to be formed. Therefore, the analysis shows that the electronic excitation of flame molecules may also considerably reduce the breakdown field. Plasma electrons generate atomic oxygen by the electron attachment of oxygen molecules in high-pressure flames. These oxygen atoms are the most reactive radicals in flames for material oxidation.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.101-102
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• 2008

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of vacuum with air are studied in non-uniform field. The gap of needle to plane was 0.5mm. The pressure of vacuum the range of 10^-4${\sim}$10^-5torr. The diameter of a plane made of the stainless steel is 150mm. As a result of the experiment, the breakdown voltage is increased about degree of vacuum increased. The electrode material influenced breakdown voltage in vacuum.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.3-6
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• 2003

The electrical and mechanical properties of dielectric paper and cable at cryogenic temperature have been investigated to optimum insulating design of high-Tc superconducting(HTS) cable. From the results, Tensile strength of PPLP in liquid nitrogen was high more than that of air, but tensile strain could know that decrease sharply. According as tensile strength increases, the breakdown stress of PPLP in liquid nitrogen was decreased because PPLP was degradated. According as bending radius multiple is decrese, breakdown voltage decreased sharply. And bending radius multiple is thought that more than about 25 is suitable.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.187-187
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• 2000

Properties of electrical discharge in flames are investigated by making use of the ionization cross section of air. Fames have three distictive features. They are hot, emit light and are weakly ionized. We investigate influence of these three characteristics of flames on the electrical breakdown. It is found that the breakdown electric field in flames is inversely proportional to the flame temperature, thereby easily generating plasmas in flames. A swarm of low-energy electrons in flames would allow significant population of electronically excited states of flame molecules to be formed. Therefore, the analysis shows that the electronic excitation of flame molecules may also considerably reduce the breakdown field. Plasma electrons generate atomic oxygens by the electron attachment of oxygen molecules in high-pressure flames. These oxygen atoms are the most reactive radicals in flames for material oxidation. How are you and your family in this new year\ulcorner Professor Choi! I plan to go back Korea on February 6. All my family members are fine and have good time because I am here. Once I am in Korea, I will call you. I am always grateful for your helpful hand. Thank you so much.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.86-93
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• 2016

It is very desirable that a mixture gas possessing excellent insulation performance is suggested for insulation on increasing high voltage. This paper proposes a $SF_6$ mixture gas based on the factors including dielectric strength, environmental impact and economic feasibility of manufacture for the insulation in eco-friendly power equipment. A suitable-$SF_6$ content was determined to improve the dielectric strength in $N_2$ and Dry Air. The examination results of the factors revealed that a $SF_6$/Dry Air mixture gas possessing the $SF_6$ content was more appropriate than a $SF_6/N_2$ mixture gas to the eco-friendly power equipment. In addition to the selection of the suitable $SF_6$ mixture gas, insulation characteristics as a function of $SF_6$ content were described from electron-detachment mechanism.

• Journal of Wind Energy
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• v.15 no.2
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• pp.5-9
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• 2024

This paper describes the insulation breakdown characteristics of 72.5 kV dry-air insulated switchgear under development for installation in a wind power generator when a lightning impulse voltage is applied. For this study, the weak point of insulation due to the electric field concentration of the switchgear's internal shape was identified by finite element method (FEM) analysis, and the shape was actually simulated to measure and analyze the polarity of the lightning impulse voltage and the insulation breakdown characteristics according to the gas pressure at dry-air pressures of 0.1 Mpa to 0.45 Mpa. This study derives the maximum electric field with a 50 % discharge probability for each switchgear internal insulation vulnerable point based on the actual test and electrical simulation, which will be useful as reference data for supplementing and changing insulation design in the future.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.2-2
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• 2003

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.24-32
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• 2011

[ $SF_6$ ]gas, which has an excellent dielectric strength and interruption performance, is used in various applications such as gas insulated switchgear (GIS) in substations. However, since $SF_6$ has a high global warming potential (GWP), it is necessary to find an eco-friendly alternative insulation gas. In order to examine the possibility of using alternative insulation gases for $SF_6$ in power distribution system equipment, the dielectric strength and physical phenomena of dry air in a quasi-uniform electric field are investigated experimentally in this paper. As a result, the breakdown voltages for positive polarity are higher than those for negative polarity under impulse voltage applications. The negative 50[%] flashover voltage, $V_{50}$ of dry air under conditions above 0.4[MPa] gas pressure, is higher than 150[kV], that is the basic impulse insulation level of distribution equipment. The $V_{50}$ increases linearly with increasing the gas pressure, regardless of the waveform and polarity of the applied impulse voltages. The voltage-time curves are dependent on the rise time of the impulse voltage and gas pressure. Furthermore, streamer discharge was observed through light emission images by an ICCD camera under impulse voltage applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.28-33
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• 2015

The needle electrode is inserted into the cross-linked polyethylene(XLPE) which is the ultra high voltage cable for electric power. By changing the tilt of the needle electrode, we investigated how the void and the thickness of the insulating layer influence the partial discharge(PD) characteristics and the insulating breakdown. In order to investigate the PD characteristics, The XLPE cable was used to the specimens and the tungsten electrode was used with the needle electrode. And the inner semi-conductive layer material of XLPE cable was used with the negative electrode by bonding with the use of conduction tape. The size of the specimens was manufactured to be $16{\times}40{\times}30[mm^3]$. We confirmed the effect on changing the PD characteristics according to the changing voltage and the tilt of the electrode after applying the voltage on the electrode from 1[kV] to 40[kV] at room temperature. In the PD characteristics, it was confirmed that the PD current of air void specimens with tilt was unstable more than that of no void specimens with tilt. It was also confirmed that the breakdown voltage was decreased because the effect of air void is more active than the change of the needle electrode tilt in the specimen with air void inside the insulation.