• Title/Summary/Keyword: Electrode Shape

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The Effect on the Dielectric Characteristics of Transformer Oils due to the High Dose Electron Beam (변압기유의 유전특성에 미치는 고조사 전자선의 영향)

  • Cho, Kyung-Soon;Kim, Lee-Doo;Kim, Suk-Wan;Kim, Wang-Kon;So, Byung-Moon;Hong, Jin-Woong
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1417-1419
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    • 1997
  • In this paper, the dielectric properties is made researches by the dose of electron beam in order to investigate the electrical properties for transformer oils due to electron beam irradiation. To measure the dielectric loss of irradiated specimen, the liquid electrode of coaxial cylindrical shape is used, and its geometric capacitance is 16 [pF]. And the dielectric dissipation factor, $tan{\delta}$, is measured by using the Video Bridge 2150. The thermal static oven with an automatic temperature controller is used so as to apply specific temperature to specimen. This experiments for measuring the dielectric loss is performed at $20{\sim}120[^{\circ}C]$ in temperature range, $30{\sim}1.5{\times}10^5[Hz]$ in frequency and $300{\sim}500[mV]$ in voltage.

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Development of Laser-Rotating An Hybrid Welding Process (레이저-회전 아크 하이브리드 용접공정의 개발)

  • Kim, Cheol-Hee;Chae, Hyun-Byung;Lee, Chang-Woo;Kim, Jeong-Han;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • v.24 no.1
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    • pp.88-92
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    • 2006
  • Laser-rotating arc hybrid welding was introduced by combining $CO_2$ laser and rotating gas metal arc welding. While the arc rotation enhances the weld pool motion, it reduces the undercut formation which is one of most critical weld defects in the conventional laser-arc hybrid welding. This research investigated the bead characteristics according to the welding parameters such as frequency of rotation, welding voltage, shielding gas composition and interspacing distance between laser and we. The welding parameters were selected to reduce spatter generation and ensure sound weld beads fur bead welding and butt welding with various joint gaps. Gap bridging ability was improved, such that the sound weld beads were achieved for butt joint with up to 2mm joint sap, with no adjustment of CTWD(Contact tip-to-workpiece distance) and electrode diameter.

Shape Design of A Spacer for 800kV GIS Interrupter (800kV급 GIS의 모델차단부용 스페이서의 형상설계)

  • Shin, Y.J.;Chang, K.C.;Park, K.Y.;Chong, J.K.;Song, W.P.;Kang, J.H.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1639-1642
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    • 1994
  • The severe conditions such as rated voltage of 800kV, gas pressure of $5kg/cm^2$ and rated lighting impulse withstand voltage of 2400kV were adopted for the design of spacers in the 800kV GIS to give a sufficient design margin. The design criteria on the maximum electric field strength of the center conductor and the insulator surface were established by considering the insulator surface characteristics, electrode area and surface effects in the unequal electric field strength of the given gap. The design parameters such as inter/outer envelope degree, thickness, inter/outer inserts, triple junction gap were determined by calculating the electric field using FLUX-2D program package and by referring to the published papers. The mechanical stress analysis was conducted on the feasible model spacers that showed good electric field distributions to confirm the sufficient mechanical design margin. The 800kV spacer designed as described above is now in the process of manufacturing.

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A Study for Estimation of Scalp Condition by Impedance (임피던스 법을 이용한 두피 상태 추정에 관한 연구)

  • Sim, M.H.;Choi, H.Y.;Jeong, I.C.;Kim, K.W.;Yoon, H.R.
    • Proceedings of the KIEE Conference
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    • 2007.10a
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    • pp.471-472
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    • 2007
  • The scalp is skin tissue for skull-protection and roots for hair growth. Therefore continuous monitoring of scalp condition is essential for hair management. However, the equipments for existent are inconvenient to use because of focus tremor and external factors(Hair Gel, Wax, accessories and so on). Furthermore there is a problem to use an expensive optical devices like CCD (Charge Coupled Device) camera or lens of 200 - 1000 magnification. It causes a difficulty of using those equipment. We design the special electrode(length 5.65mm, diameter 0.8mm of needle shape) and the impedance system(1kHz, 78uA). Tn this paper, we can measure scalp impedance with our system. Moreover, we find the possibility of classifying scalp condition with measured impedance values. For the classification of scalp condition, we used ARAMO-TS as an imaging system. In conclusion, the problem of existent devices could be improved using these method. It also has a benefit of continuous monitoring of scalp condition.

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The Analysis of Corona Discharge of Surface Flashover Model for Aging Diagnosis of Power Facility (전력설비의 열화 진단을 위한 연면방전 모델에서의 코로나 방전 특성 분석)

  • Pang, Man-Sik;Choi, Jae-Hyeong;Kim, Woo-Jin;Kim, Young-Seok;Kim, Sang-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.4
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    • pp.314-318
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    • 2011
  • Recently, ultrasound, infrared detector, V-I characteristic, gas analysis, UV (ultra-violet rays) camera etc. is used as inspections and diagnoses of the safety of power equipment. Especially, UV camera have attracted a great deal of interest from the view point of easy judgement. UV camera is used corona discharge. One of the most important and difficult problems to be solved filer design, materials and corona discharge. This paper is studied on the temperature characteristics, UV generation and shape analysis and corona pulse count according to the electrode distance and applied voltage. Also, Corona discharge characteristics in air are analyzed using prototype UV camera of Korea. UV generation due to surface discharge of AC is higher than that of DC.

A Study on Minimum Ignition Energy by Controlled Discharge Energy (방전에너지 제어에 의한 최소점화에너지의 고찰)

  • Choi, Sang-Won;Ohsawa, Atsushi
    • Journal of the Korean Society of Safety
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    • v.22 no.1 s.79
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    • pp.36-39
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    • 2007
  • It is important to know Minimum Ignition Energy(MIE) of flammable materials for ignition hazard of chemical processes etc.. Currently a capacitor discharge is used mainly to measure the MIE. Then, it is impossible to control actively discharge energies and discharge time because the MIE measurement uses a high voltage capacitor and fixed capacitor. However, the control of discharge energy and discharge time will be convenient if self-sustain discharge is used. In this paper, we measured the MIE by self-sustain discharge of a pulse shape to propose the new measuring method of the MIE. AS a result, ignition energies are increased gradually as discharge duration time gets longer, and discharge current grows larger. Also, an arc discharge and a glow discharge occurred during the experimental period, and the ignition by glow discharges happened when discharge duration time was $90{\mu}s$, discharge current was 8A and 1A Especially, the MIE occurred the 0.05mm and 0.08mm of the gap distance between discharge electrode in the same discharge duration time.

A Comparison of the Discharged Products in Environmentally Benign Li-O2 and Na-O2 Batteries (친환경의 리튬 - 공기전지와 소듐 - 공기전지의 방전 생성물 비교 분석 연구)

  • Kang, Jungwon
    • Resources Recycling
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    • v.25 no.3
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    • pp.82-87
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    • 2016
  • The discharged products of Li-$O_2$ and Na-$O_2$ batteries using ether-based electrolyte as next-generation battery system were analyzed. The morphology of the discharged products showed millet-like shape in the both battery systems by FESEM. However, the discharged product, $Li_2O_2$ showed amorphous-like form in the Li-$O_2$ cell while crystalline $NaO_2$ is formed in the Na-$O_2$ cell when confirmed by X-ray diffraction. In this work, we comprehended a principle operating mechanism of Li-$O_2$ and Na-$O_2$ battery.

Microgripper driven by E-T(Electro-Thermal) actuator (E-T(Electro-Thermal) 액츄에이터를 이용한 microgripper)

  • Park, Ho-Joon;Lee, Hyun-Ki;Pak, Jung-Ho
    • Proceedings of the KIEE Conference
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    • 1999.07g
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    • pp.3325-3327
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    • 1999
  • A microgripper driven by E-T (electro-thermal) actuators has been designed and fabricated by surface micromachining. This microgripper consists of two E-T actuators. Each actuator has two arms with different widths joined at the end to form a 'U' shape. The wider 'cold' arm has a narrow flexure at the end (anchor or electrode side) for easy bending, This actuator can be fabricated with only two masks - one for the sacrificial layer and the other for the poly-Si structure layer. An E-T actuator bends its arm due to unequal thermal expansion between the 'cold' arm and the 'hot' arm, This actuator tip moves laterally in an arcing motion towards the cold arm side when the structure is unevenly heated by the applied current. Therefore each microgripper is actuated inwards and can hold a micro object. The fabricated E-T actuator was operated in the range of $2{\sim}12V$ and $1{\sim}5mA$. and maximum tip displacement was $13.6{\mu}m$. This device may become useful in many applications because an E-T actuator can be designed and fabricated easily, and obtain large displacement.

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Optical and Electrochemical Property of Self-Assembled Monolayers Containing Viologen Derivative by EQCM Study (EQCM법을 이용한 자기조립된 Viologen 유도체의 광학적 특성 및 전기화학적 특성 연구)

  • Lee, Dong-Yun;Park, Sang-Hyun;Park, Jae-Chul;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1305-1306
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    • 2006
  • A monolayer assembly of anthracene-viologen linked thiol ($AMVC_{8}SH$) was fabricated on a gold electrode by self-assembly method. Structural property of the self-assembled monolayers (SAMs) was carried out by optical and electrochemical method. Firstly, we investigated PL spectrum and UV/visible absorption for the optical properties in solution state. Secondly, we determined the characteristics of charge transfer in different electrolyte solutions by electrochemical quartz crystal microbalance (EQCM). From the data, the PL spectrum and UV/visible absorption were observed and the well-defined shape peaks were nearly equal charges during redox reactions and existed to an excellent linear relationship between the scan rates and existed to currents. The mass change was determined during redox reaction. The mass change behavior of SAMs was not only governed by the mobility of the ion in the viologen but the valence of the ion in the electrolyte solution.

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Investigations on PD Characteristics of Thermal aged Palm and Corn Oil for Power Transformer Insulation Applications

  • Senthilkumar, S.;Karthik, B.;Chandrasekar, S.
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1660-1669
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    • 2014
  • Partial discharge (PD) detection plays a major role in the life time assessment of liquid insulation in power transformers. Many research works are being carried out to replace conventional mineral oil insulation in transformers by vegetable oils. It is necessary to understand the PD characteristics of vegetable oils before recommending them as an alternate for mineral oil. In this paper, the breakdown strength and PD characteristics of palm and corn oil were investigated in both unaged and thermally aged conditions. Laboratory experiments were performed as per IEC test procedures. PD signals were measured using wide band detection system. Phase resolved PD pattern of vegetable oils and mineral oil were compared. Effect of increase in voltage stress on the PD pattern of palm and corn oil were studied. Time and frequency domain analysis of PD pulses at needle-plane electrode configuration was carried out. Statistical analysis of PD pattern i.e. skewness and shape parameter variations with respect to applied thermal stress were also carried out. From the results, it is observed that palm and corn oils have better breakdown strength and PD characteristics even under long-term thermal stress and hence they can be used for power transformer applications.