• Title/Summary/Keyword: External DC electric field

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The Effect of External DC Electric Field on the Atmospheric Corrosion Behaviour of Zinc under a Thin Electrolyte Layer

  • Liang, Qinqin;YanYang, YanYang;Zhang, Junxi;Yuan, Xujie;Chen, Qimeng
    • Corrosion Science and Technology
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    • v.17 no.2
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    • pp.54-59
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    • 2018
  • The effect of external DC electric field on atmospheric corrosion behavior of zinc under a thin electrolyte layer (TEL) was investigated by measuring open circuit potential (OCP), cathodic polarization curve, and electrochemical impedance spectroscopy (EIS). Results of OCP vs. time curves indicated that the application of external DC electric field resulted in a negative shift of OCP of zinc. Results of cathodic polarization curves measurement and EIS measurement showed that the reduction current of oxygen increased while charge transfer resistance ($R_{ct}$) decreased under the external DC electric field. Variation of OCP negative shift, reduction current of oxygen, and $R_{ct}$ increase with increasing of external DC electric field strength as well as the effect of external DC electric field on double-layer structure in the electrode/electrolyte interface and ions distribution in thin electrolyte layer were analyzed. All results showed that the external DC electric field could accelerate the corrosion of zinc under a thin electrolyte layer.

DC and AC current transport characteristics of HTS tapes with external magnetic field (외부자계 영향에 따른 HTS 선재의 직$\cdot$교류 통전 특성)

  • 임성우;최용선;최효상;황시돌;정영호
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.02a
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    • pp.15-18
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    • 2003
  • HTS(High Temperature Superconductor) tapes have dependence on critical characteristics such as electric, magnetic field and temperature. In order to confirm these effects, we examined the current transport characteristics of HTS tapes. First, after being fed DC and AC, the dependence of HTS tapes of 10cm on external magnetic field was investigated. On centeral region of HTS tape, about 1cm, external magnetic field was applied. Second, after applying DC of 50A to HTS tapes, we applied time variable magnetic field about 100mT and investigated the quench characteristics. Finally, AC, which is about 10 times of I$_{c}$, was applied to HTS tapes and over current characteristics were investigated. The data acquired in this study will be used as a source for the study of HTS cable conductor which is supposed to carry on.n.

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DC V-I Characteristics of a High Temperature Superconductor for a 600 kJ Superconducting Magnetic Energy Storage Device in an Oblique External Magnetic Field (경사 외부자장에 대한 600 kJ급 SMES용 HTS도체의 DC V-I 특성)

  • Li, Zhu-Yong;Ma, Yong-Hu;Ryu, Kyung-Woo;Choi, Se-Yong;Kim, Hae-Jong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.1
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    • pp.79-84
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    • 2008
  • We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.

Durability Estimation for ER(Electro-Rheological) Fluids of Arabic Gum Components (아라빅 검 성분의 ER유체에 대한 내구성 평가)

  • Kim, O.S.;Park, W.C.
    • Journal of Power System Engineering
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    • v.5 no.4
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    • pp.61-66
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    • 2001
  • Electro-Rheological(ER) fluids undergo a phase-change when subjected to an external electric field, and this phase-change typically manifests itself as a many-order-of magnitude change in the rheological behavior. This paper presents experimental results on material properties for an ER fluids of arabic gum components subjected to electrical fatigues. As a first step, ER fluids are made of arabic gum 25% of particle weight-concentration. Following the construction of test mechanism for estimated durability of ER fluid, the dynamic yield stress, shear stress and current density of the ER fluids are experimentally distilled as a function of DC electric field. The durability estimation of operated ER fluids are distilled and compared with those of unused ER fluids. In addition, the surface roughness of the employed electrode for copper and aluminum are evaluated as a function of the number of the electric-field cycles.

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A Study on the Microwave Reflection of Plasma in a Magnetic Field (방전프라즈마내 자계에 의한 마이크로파 반사특성)

  • 김봉열;김정기
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.6 no.1
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    • pp.12-18
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    • 1969
  • The characteristics of microwave reflection in the media of cold gaseous plasma is analysed to various external magnetic flux density. The DC discharge plasma is generated in the rectangular waveguide which contains two electrodes and helium gas at the pressure of 10-2mm Hg. The reflected and transmitted power of microwave is measured when the electric field is parallel to, and perpendicular to the external magnetic field. It shows that the reflected power is increased as the magnetic flux density is increased in the parallel case, but the maximum value of the reflected power is occured at the cyclotron resonance (3120 Gauss) in the perpendicular case.

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DC Arc Extinction Using External Magnetic Field in Switching Device

  • Cho Hyun-Kil;Lee Eun-Woong;Jeong Jong-Ho
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.4
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    • pp.306-311
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    • 2005
  • In this paper, the electromagnetic force acting in the arc column of 3 different extinction units is compared with using the FEM (Finite Element Method) and the arc velocity is calculated by the drag force of the fluid mechanics. The experiment for breaking the arc current was performed in each model at 100 volts in order to measure the arcing time. The outcome was compared with the computing value. As a result, this paper proposes that the divided U-shaped grid is able to shorten arcing time and improve the electric performance. It also suggests a methodology for comparing and analyzing the result obtained by simulation and experiment.

Numerical Modeling of Charge Transport in Polymer Materials Under DC Continuous Electrical Stress

  • Hamed, Boukhari;Fatiha, Rogti
    • Transactions on Electrical and Electronic Materials
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    • v.16 no.3
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    • pp.107-111
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    • 2015
  • Our work is based on the development of a numerical model to develop a methodology for predicting the aging and breakdown in insulation due to the dynamics of space charge packets. The model of bipolar charge transports is proposed to simulate space charge dynamic for high DC voltage in law-density polyethylene (LDPE), taking into account the trapping and detrapping of recombination phenomena, this model has been developed and experimentally validation. Theoretical formulation of the physical problem is based on the Poisson, the continuity and the transport equations as well as on the appropriate models for injection. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges, conduction and displacement current densities, and the external current.

Studies on electrokinetic motion of FULLERENE/POLYSTYRENE microparticles in liquid crystal medium for electronic paper displays (전자종이 제작을 위한 FULLERENE/POLYSTYRENE microparticles의 움직임연구)

  • Kim, Mi-Young;Kim, Kun-Ji;Kim, Sung-Min;Jo, Eun-Mi;Srivastava, Anoop Kumar;Jung, Jun-Ho;Ji, Seung-Hoon;Lee, Myong-Hoon;Lee, Seung-Hee;Lee, Gi-Dong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.341-342
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    • 2008
  • The dynamics of nano particles in LC medium under an external electric field is of theoretical and technological interest. In this work, the dynamical characteristics of fullerene $(C_{60})$ particles in liquid crystal (LC) medium under dc electric field have been investigated. This effect was studied for homogeneously aligned nematic LC cells driven by in-plane field. The $C_{60}$ was found to be aggregated in a form of cluster inside the LC medium. Hence polystytene was used to protect the aggregation of $C_{60}$ in LC medium. When the electric field was applied, the fullerenes start to move in direction of applied electric field. The density of $C_{60}$'s particles at the electrodes increase with increase in the value of applied electric field. The dynamical motions of fullerene $(C_{60})$ particles in liquid crystal (LC) suggest that fullerene can be designed for electrophoretic displays (i.e., electronic ink).

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Analysis and the measurement of the variation of electric field in air and oil using optical measuring system (광계측 시스템을 이용한 유.기중 코로나 방전의 전계변화 측정 및 비교분석)

  • Ma, Ji-Hoon;Ryu, Cheol-Hwi;Kang, Won-Jong;Chang, Yong-Moo;Koo, Ja_Yoon
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1668-1670
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    • 2002
  • Since more than two decades, the conventional PD detecting systems have been employed in order to detect the partial discharges occurring inside the HV power apparatus for their diagnosis by use of different type of detection such as acoustic and UHF detection method. Regardless of their wide on-site application, a certain number of technical inconveniences have been disclosed as follows : multistage amplification. large volume, susceptible to external noise and high price. In this respect, the optical measurement techniques are widely proposed in these days in this concerned field ascribed to the following advantages : immune to external EMI noise and broad band response of the Pockels cell covering from DC to GHz. However, the reliability of several proposed techniques enabling to measure the electric field inside the large high power apparatus has not yet been well approved In this work, an optical measuring system, based on the Pockels effect, has been developed for measuring the field variation due to the corona discharges occurring in air and in oil. This system consists of He-Ne laser, single mode optical fiber, multi mode optical fiber, polarizing film, Y-cut LiNbO3 cell, photo detector, digital oscilloscope and personal computer with GPIB. For this purpose, optical probe has been specially designed and realized and put into the needle-plane electrode. Afterward, same measurement is carried out in oil. We demonstrate the characteristic of the optical measuring system and the measurement results.

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The Influence of Transverse Magnetic Field for Shortening DC Arc Time (직류 아크 소호 시간을 단축시키는 직교자계의 영향)

  • Lee, Eun-Woong;Cho, Hyun-Kil
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.3
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    • pp.146-154
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    • 2006
  • We derived a theory of increasing electromagnetic force which acts on arc column for reducing arcing time between electric contacts. A simulation method of arc velocity is presented by calculating blowout force using 3D FEM and drag force acting on arc column. This paper proposes 3 types arc extinguish chamber of different flux path and presents the specific electromagnetic force and arc velocity of each model by the analysis. The result of analysis and experimental proposes the prediction method of arc time when all conditions are same except external magnetic field.