• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.51-56
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• 2001

In this paper, the effect of magnetic field on corona discharge phenomena was experimentally investigated in the needle-plate electrode geometry. Needle-plate geometry discharge system with magnetic field at a right angle to the electric field was made. The corona discharge characteristics with magnetic field were investigated and compared with the corona characteristics without magnetic field in atmospheric pressure. As a result, in case of positive DC corona discharge with magnetic field, corona discharge zone was significantly wider, corona current was lower, and breakdown voltage was higher than those without magnetic field. However, in case of negative DC corona discharge with magnetic field, corona current was slightly higher and breakdown voltage was lower than those without magnetic field. It is thought that this result is due to cyclotron motion of charged particles such as electron and ion by magnetic field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.85-90
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• 2006

This paper presents experimental results relating to the preliminary breakdown characteristics in $SF_6/CO_2$ gas mixtures under a highly non-uniform electric field. The impulse pre-breakdown developments are investigated by the measurements of corona current and light emission images. As a result, the preliminary breakdown development mechanisms for both the positive and negative polarities were fundamentally same. The first streamer corona was initiated at the tip of needle electrode, and the leaders developed with a stepwise propagation and bridged the test gap. The pause time of leader pulses in the positive polarity was significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity. The discharge channel path in the positive polarity was zigzag, and the leader channel in the negative polarity was thicker and brighter than that in the positive polarity.

• Journal of the Korean Vacuum Society
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• v.11 no.1
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• pp.68-75
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• 2002

It is observed the characteristic of the microwave air plasma in the wide range of the operating pressure, 1 mTorr ~ 760 Torr. The microwave air plasma was generated by an AC-type microwave source manufactured with a magnetron taken from a commertial microwave oven and the input power was fixed at 370 W. Characteristics of the plasmas were observed by an injection Langmuir probe and an OES(Optical Emission Spectroscopy). The breakdown electric field is drastically changed at 500 mTorr. For < 500 mTorr, the ratio of the breakdown electric field and the pressure decreased inversely to the pressure, $5.7\times10^4$V/m-Torr.However, the ratio increased linearly as 43 V/m-Torr for the operating pressure, > 500 mTorr. The minimum breakdown electric field was observed about 12. kV/m at 500 mTorr. It corresponds that the input frequency equals to the collision frequency. The effective collision cross section of the air at this pressure was calculated as $9.23\times10^{-l6}\textrm{cm}^2$.The results of the OES measurement revealed that the main ions were composed of the oxygen, argon, and nitrogen for > 500 mTorr. In contrast, only oxygen and argon ions were dominated for < 500 mTorr. ion temperature of oxygen (O(II)) in the air was decreased from about 1.2 eV to 0.5 eV as the pressure increased. Langmuir probe data shows that the plasma density for < 500 mTorr was higher that for > 500 mTorr.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.78-81
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• 2004

In this paper, the effect of adhesion properties of semiconductive-insulating interface layer of silicone rubber on electrical properties was investigated. Surface structure and adhesion of semiconductive silicon rubber by surface asperity was obtained from SEM and T-peel test. In addition, ac breakdown test was carried out for elucidating the change of electrical property by roughness treatment. From the results, Adhesive strength of semiconductive-insulation interface was increased with surface asperity. Dielectric breakdown strength by surface asperity decreased than initial Specimen, but increased from Sand Paper #1200. According to the adhesional strength data unevenness and void formed on the silicone rubber interface expand the surface area and result in improvement of adhesion. Before treatment Sand Paper #1200, dielectric breakdown strength was decreased by unevenness and void which are causing to have electric field mitigation small. After the treatment, the effect of adhesion increased dielectric breakdown strength. It is found that ac dielectric breakdown strength was increased with improving the adhesion between the semiconductive and insulating interface.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.105-108
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• 2020

In this study, experiments and simulations were conducted for a 1,200-V-class trench Si insulated-gate bipolar transistor (IGBT) with a small cell pitch below 2.5 ㎛. Presently, as a power device, the 1,200-V-class trench Si IGBT is used for automotives including electric vehicles, hybrid electric vehicles, and industrial motors. We obtained a breakdown voltage of 1,440 V, threshold of 6 V, and state voltage drop of 1.75 V. This device is superior to conventional IGBTs featuring a planar gate. To derive its electrical characteristics, we extracted design and process parameters. The cell pitch was 0.95 ㎛ and total wafer thickness was 140 ㎛ with a resistivity of 60 Ω·cm. We will apply these results to achieve fine-pitch gate power devices suitable for electrical automotive industries.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.194-195
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• 2007

$SF_6$ gas used widely as insulating component in electric power industry has excellent in insulation and arc extinguishing performance in gas-insulated switchgear. However, the concern about eco-friendly alternative gas is currently rising because $SF_6$ gas is one of the main greenhouse gases. In this paper, dry-air and composite-insulation (dry-air+epoxy) as the alternative technology for $SF_6$ gas insulation is studied. Under the gas pressure ranged from 0.1 to 0.6MPa, the breakdown voltage of dry-air were measured in AC electric field. The data of composite-insulation were acquired by changing the thickness of epoxy used in each composite-insulation under the same condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.213-218
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• 2013

In this study, epoxy/mica composite was prepared by mixing with mechanical stirrer together with homogenizer, and the effect of amino-type silane coupling agent was also studied. To reduce the viscosity without any decrement of other properties, 1,4-Butanediol diglycidyl ether (1,4-BDGE) as an aliphatic epoxy reactive diluent was introduced to the epoxy/mica composite in order to use as vanish for high voltage motor and generator stator winding. It was confirmed by scanning electron microscopy (SEM) observation that interfacial characteristics between organic epoxy and inorganic mica was modified by coupling agent treatment so that glass transition temperature increased, and tensile strength and electrical breakdown strength increased. The properties were estimated by Weibull statistical analysis and the ac electrical breakdown strength was 20.2% modified by treating silane coupling agent.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.36-42
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• 1999

Field emission behaviors from diamond-like carbon films were investigated. The films were deposited on n-type Si wafer by ion beam sputtering method using 3 cm Kaufman type ion source. Regardless of the film thicknesses and atomic bond structure, the emission current was much enhanced by electrical breakdown between anode and the film surface. The effective work function was estimated to be about 0.1 eV. In order to identify the emission site, tungsten tip was scanned the damaged region damaged region but localized to a specific site. Analysis using Auger electron spectroscopy and SEM shows that SiC compound was not a sufficient condition for the electron emission. This result showed that the enhanced emission was mainly due to the changes in the chemical bond of the damaged region rather than the enhanced electric field caused by the morphological change.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.289-292
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• 1990

This study is to develope a spacer having almost uniform field distribution along the profile by controlling the high electric field in tensification at earthed part, especially triple junction in the spacer-electrode-gas boundary interface. Based on the extensive field calculation using CSM, a model spacer has been manufactured and tested. The test results show that the breakdown strength of the spacer is almost same as that of SF6 gas itself without spacer.