• Title/Summary/Keyword: Air-gap length

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Breakdown Characteristics of Air in the Gap between Line Conductor and Plane Electrode in Case of Combustion Flame on the Plane Electrode (선도체 대 평면전극 갭에서 평면전극에 연소화염 존재시 대기의 절연파괴 특성)

  • Kim, In-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.4
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    • pp.73-80
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    • 2013
  • Breakdown characteristics of air in the vertical arrangement of line conductor and plane electrode in case of combustion flame on the plane electrode are examined by the application of AC. and DC voltages to the gap. In order to investigate the effect of paraffin flame on the breakdown characteristics of air, flashover voltages are measured according to the variation of the gap length and the horizontal distance between the flame and the line conductor. As the result of the experiment, flashover voltages are substantially lowered down to 29.8% in case of the AC voltage, and 16.1% in case of the negative DC voltage, when in the presence of the flame. from 100% when in the absence of flame. Flashover voltages of air in the range of smaller than 3㎝ at the horizontal distance are increased in the proportion of the gap length and the horizontal distance in case of both AC and negative DC voltages. But before the flashover occurs, the flame is extinguished by such corona wind that is produced from the line conductor when the gap length and the horizontal distance reach to a certain degree. The effect of relative air density and the phenomenon of thermal ionization are analysed as the reduction factors of flashover voltages, due to high temperature of the flame.

Characteristic Analysis of Air-gap Control System in Performance Test Machine of a LIM for Railway Transit (철도차량용 선형유도전동기 성능시험기의 공극조절 시스템 특성 연구)

  • Park, Chan-Bae;Lee, Hyung-Woo;Lee, Byung-Song;Park, Hyun-June;Kwon, Sam-Young;Han, Kyung-Hee
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.1955-1961
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    • 2008
  • A lot of researches on a linear induction motor(LIM) have been advanced to realize a traction system with high efficiency and performance for railway transit for a long time. However, most of them are limited in design of a LIM part such as Primary and Secondary. At a LIM which is traveling, the change of an air-gap(It occurs by a construction tolerance of a secondary reaction plate) becomes the cause which decreases a smoother ride and the efficiency of railway transit system. Therefore, uniform air-gap operation of LIM is important issue to improve the system efficiency. However, the researches which control the air-gap length of the LIM with technical and high-cost problem have been not advanced a lot. Therefore, in this research, it is introduced an air-gap control system for performance test machine of a scale-downed LIM which is able to control the air-gap length of the LIM and monitor a variety of performance changes of the propulsion system, and conducted a research on feasibility of the system based on characteristic analysis.

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Flashover Characteristics of Air in the Arrangement of Cylinder-Shaped Rod and Plane Electrode in Case of Flame on the Plane Electrode (평단봉대평판 전극배치에서 평판 전극에 화염이 존재할 때 공기의 섬락전압 특성)

  • Kim, In-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.4
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    • pp.82-87
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    • 2012
  • In this paper, flashover characteristics of air in the vertical arrangement of cylinder-shaped rod and plane gap in the case of combustion flame on the plane electrode were examined under the application of a.c. and d.c. high-voltages. In order to investigate the effect of propane flame on the flashover characteristics of air, flashover voltages in accordance with the variation of the gap length and the horizontal distance between the flame and the high-voltage rod electrode were measured. As the result of the experiment, flashover voltages in the presence of the flame were substantially lowered than those in the absence of flame, and the polarity effects with the d.c. voltages on appeared owing to the flame. Flashover voltages of air were increased in the proportion of the gap length and the horizontal distance in the case of both a.c. and d.c. voltages, but the flame was extinguished by such corona wind that was produced from the rod electrode when the gap length and the horizontal distance reached to a certain degree.

Computer Simulation of Coating Behavior Including Air for Various Coater Geometries and Operational Conditions (코팅 공정에서 공기를 고려한 코터형상 및 운전조건에 따른 코팅현상 해석)

  • Kim, H.Y.;Lyu, M.Y.;Choi, J.G.
    • Transactions of Materials Processing
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    • v.18 no.2
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    • pp.156-159
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    • 2009
  • Slot coating has been wide spread in photo-resist coating on the glass for liquid crystal display. Die in slot coater consists of manifold and land. Material comes in inlet of the die and flow into the manifold and then flow out through the land. The coating thickness variations along the die length depend upon inside of die design such as manifold and die land. However the coating thickness variations along the moving direction(coating direction) of the coater depend upon the operational conditions of coater as well as die lip design. The coating behaviors including atmospheric air have been investigated in this study. Die geometries considered in this study were nozzle gap and length of the die lip. Coating gap and coating speed were the variables fur coating operational conditions. When the nozzle gap and length of die lip increased climbing effect of PR on the downstream die lip was reduced. Subsequently uniformity of coating thickness improved. Uniformity of coating thickness also enhanced as coating gap and coater speed increased. The uniformity of coating gap was related to the velocity vector distributions on the coating surface.

Parallel Operation Characteristics of Two Linear Induction Motors (선형 유도전동기의 병렬 운전 특성 실험)

  • Park Seung-Chan;Kim Kyung-Min
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.44-48
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    • 2005
  • In general, the parallel-connected linear induction motors(LIM) are fed by one VVVF inverter in the magnetically levitated vehicle(MAGLEV) or linear motor subway drives. The air gap length of the parallel-connected linear induction motors operating at a grade or curved sections can be different each other. The air gap difference of the two motors attached to the same module causes unequal phase currents, asymmetic thrust and attraction force generation. In this paper, parellel-connected linear induction motors are operated by one IGBT inverter under the different air gap condition so that the phase current characteristics are examined experimentally.

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A Elicitation of Polynomial Equation of Thrust Coefficient for Linear Synchronous Motor by Experimental Design Method (영구자석의 overhang 길이 및 skew 효과를 고려한 LSM 추력함수 도출)

  • Jang, Ki-Bong;Pyo, Se-Ho;Kim, Gyu-Tak
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.6
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    • pp.1105-1109
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    • 2009
  • This paper deals with a polynomial thrust equation of a permanent magnet linear synchronous motor that is considered by a skew and overhang effects of permanent magnet. The skew length, the overhang length, the width and height of permanent magnet, the teeth length and air-gap length which effect to the flux density of air-gap are selected as variables of the polynomial thrust equation. Polynomial thrust equation is elicited by the 6 parameters. The results are satisfied that the values by polynomial thrust equation are compared ones by using 3-dimensional finite element analysis and experiment.

Breakdown Characteristics of a Vertical Sphere-Plane Air Gap in the Presence of Combustion Flame (수직배치 구대평판 공기 갭에서 연소화염 존재시의 절연파괴 특성)

  • Kim, In-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.5
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    • pp.79-84
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    • 2011
  • In this study, breakdown characteristics of a vertical sphere-plane air gap in the presence of combustion flame were examined under the application of a.c. and d.c. high-voltages in order to investigate the effect of flame on the dielectric strength of air. Propane gas is used as the fuel of the flame, and the temperature distribution of air around the flame is measured. The polarity effects for the d.c. voltages and breakdown voltages of air when applied both of a.c. and d.c. voltages were examined in the case of the variation of the gap length and the horizontal distance between the flame and the high-voltage sphere electrode. The influence of relative air density, electrification and shape changes of the flame as factors that affect the breakdown voltages were discussed.

Study on the Noise Reduction in the Rotary Compressor using BLDC Motor (BLDC 모터를 적용한 로터리 컴프레서 소음 저감에 관한 연구)

  • Kim, Jin-Soo;Lim, Kyung-Nae;Ku, Se-Jin;Lee, Jang-Woo;Jeon, Si-Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.674-681
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    • 2008
  • The main noise source of the BLDC rotary compressor for air conditioner was analyzed by using the measurement of noise and vibration, noise contour, and experimental modal analysis. The source is presumed to the mechanical resonance excited by the electromagnetic attractive force of the BLDC motor. To reduce the excessive noise of the BLDC rotary compressor due to the mechanical resonance, air-gap was enlarged. Its validation was conducted by the analysis of the electromagnetic attractive force which is generated by the BLDC motor. By enlarging the length of air-gap, the noise in the compressor and air conditioner was significantly improved by 2.5dB(A) and 4.5dB(A), respectively.

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The Characteristic Analysis of An Inverter-Fed Induction in Variation of Airgap Length (인버터 구동유도전동기의 공극길이 변화에 따른 특성해석)

  • Kim, J.W.;Kwon, B.I.;Hong, S.H.;Kim, B.T.;Woo, K.I.
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.816-818
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    • 2001
  • This paper shows the characteristic analysis for an inverter fed induction motor by the 2-D F.E.A. in variation of the air gap length. Harmonic effects of the induction rioter with different air gap length driven by the 6 step voltage of inverter ate investigated. And the results of the characteristic analysis on the inverter fed induction motor are compared with those of sinusoidal voltage fed motor.

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Dependence of Ozone Generation in a Micro Dielectric Barrier Discharge on Dielectric Material and Micro Gap Length

  • Sakoda, Tatsuya;Sung, Youl-Moon
    • KIEE International Transactions on Electrophysics and Applications
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    • v.4C no.5
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    • pp.201-206
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    • 2004
  • In order to investigate the optimum conditions for the effective ozone formation in a dielectric barrier discharge, measurements of ozone concentration were carried out for various conditions such as the gap length, the dielectric material and the operating gas. It was found that the optimum discharge conditions differed exceedingly in the types of operating gases and dielectric materials. In dry air, dielectric material with low dielectric constant and thermal conductivity, which might contribute to the restriction of the gas temperature rise in the discharge region, proved effective in obtaining both high ozone yield and concentration. The optimum gap length was considered to be in the range of 600-800 mm. In oxygen, using a quartz glass disk as a dielectric material, the required condition to obtain the high ozone yield and concentration was expanded.