• Title/Summary/Keyword: Corona Charging Process

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Charge Distribution of Submicron Particles Charged by Spray Electrification or Corona Discharge (분무 및 코로나 방전에 의해 대전된 서브마이크론 입자의 대전량 분포)

  • Lee, Jae-Bok;Bae, Gwi-Nam;Hwang, Jeong-Ho;Lee, Gyu-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.1
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    • pp.124-132
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    • 2001
  • This paper reports on the charge distribution measurements of submicron particles for three different charging mechanisms, which are spray electrification, bipolar ionization and corona discharge process, respectively. The number of elementary charges per particle was investigated by classifying and counting of a discrete mobility class. Charge distribution measurements were performed with NaCl particles generated from a collision atomizer for 0.01, 0.1, 1% NaCl solutions. Experimental results show than charge level of atomized NaCl particles is high and decreases with increasing the dissolved ion concentration. The charge level of the atomized NaCl particles can be reduced to that o Boltzmann equilibrium conditions by the bipolar ionization(Po(sup)210 bipolar ionizer). The charge level on NaCl particles passing through the corona discharge reactor is much higher than those of atomized or bipolar ionized NaCl particles. The evaluation of these measurements results in charge distribution of the submicron particles.

Design and Performance Evaluation of a Faraday Cage and an Aerosol Charger (패러데이 케이지와 에어로졸 하전기의 설계 및 성능평가)

  • Ji, Jun-Ho;Bae, Kwi-Nam;Hwang, Jung-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.3
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    • pp.315-323
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    • 2004
  • An electrical cascade impactor is a multi-stage impaction device to separate airborne particles into aerodynamic size classes using particle charging and electrical detection techniques. A Faraday cage and an aerosol charger, which are basic components of the electrical cascade impactor, were designed and evaluated in this study. The low-level current response of the Faraday cage was investigated with changing particle size and air flow rate by using sodium chloride (NaCl) particles. The response of the prototype Faraday cage was very similar to that of a commercial aerosol electrometer (TSI model 3068) within ${\pm}$5% for singly-charged particles. The response linearity of the prototype Faraday cage could be extended up to flow rate of 30 L/min. For the performance evaluation of the aerosol charger the monodisperse liquid dioctyl sebacate (DOS) particles, with diameters of 0.1∼0.8$\mu\textrm{m}$, were generated using spraying from an atomizer followed by evaporation-condensation process. Typical performance parameters of the aerosol charger such as P$.$n, wall loss, and elementary charges per particle were evaluated. The performance of the prototype aerosol charger was found to be close to that of the aerosol charger used in an electrical low pressure impactor (ELPI, Dekati).

Failure analysis of capacitor for sub-module in HVDC (HVDC 서브모듈용 커패시터의 고장 분석)

  • Kang, Feel-soon;Song, Sung-Geun
    • Journal of IKEEE
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    • v.22 no.4
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    • pp.941-947
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    • 2018
  • In general, capacitors have a large influence on the life of the system due to frequent charging and discharging. In this paper, we analyze the cause of the core failure of high voltage, high current HVDC sub-module film capacitor and analyze the precautions of the capacitor design and manufacturing process. First, the cause of the fault, the failure mode, and the effect are analyzed through the FMEA of the capacitor. To quantitatively evaluate the causes and effects of faults that have the greatest effect on the failure of a capacitor, a fault tree for the capacitor is presented and the failure rate is analyzed according to the design parameters and the driving conditions. It is verified that the main cause of capacitor failure is the capacitance change, and it is necessary to minimize the temperature rise, corona occurrence, electrode expansion, and insulation distance decrease during capacitor design and manufacturing process in order to reduce the failure rate of the capacitor.