• Title/Summary/Keyword: Limited Current

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Operational Characteristics of the FCL Using the Mechanical Contact in the Power System (기계적 접점을 이용한 FCL의 동작 특성)

  • Jung, Byung-Ik;Choi, Hyo-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.5
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    • pp.878-882
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    • 2016
  • These days, SFCLs are being developed in order to limit fault current. However, the superconducting elements that limit the fault current have such problems as capacity increase and require auxiliary devices including cooling device. If devices that comprise the current power network can withstand fault current for at least one cycle, it is possible to limit the fault current with current limiting elements by bypassing it on the fault line. In this study, the fault current limiter was configured with current transformer, vacuum interrupter, and current limiting element. Through the experience, it was confirmed that the fault current was limited within one cycle. The superconducting element, as a current limiting element, limited the fault current by 80 % within one cycle from fault occurrence, and the passive element limited it more than 95 %. Also, through the comparison between resistance curve and power consumption curve, it was confirmed that the current limiting element using a passive element was more stable than the superconducting element that required capacity increase and other auxiliary devices. It was considered that the FCL proposed in this study could limit fault current stably within one cycle from fault occurrence by using the existing power technologies such as fault current detection and solenoid valve operating circuit.

Current Density Equations Representing the Transition between the Injection- and Bulk-limited Currents for Organic Semiconductors

  • Lee, Sang-Gun;Hattori, Reiji
    • Journal of Information Display
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    • v.10 no.4
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    • pp.143-148
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    • 2009
  • The theoretical current density equations for organic semiconductors was derived according to the internal carrier emission equation based on the diffusion model at the Schottky barrier contact and the mobility equation based on the field dependence model, the so-called "Poole-Frenkel mobility model." The electric field becomes constant because of the absence of a space charge effect in the case of a higher injection barrier height and a lower sample thickness, but there is distribution in the electric field because of the space charge effect in the case of a lower injection barrier height and a higher sample thickness. The transition between the injection- and bulk-limited currents was presented according to the Schottky barrier height and the sample thickness change.

Current-Voltage Characteristics of Organic Light-Emitting Diodes with a Variation of Temperature (온도 변화에 따른 유기 전기 발광 소자의 전압-전류 특성)

  • Kim, Sang-Geol;Hong, Jin-Ung;Kim, Tae-Wan
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.7
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    • pp.322-327
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    • 2002
  • Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/Alq$_3$/Al to understand conduction mechanism. The current-voltage characteristics were measured in the temperature range of 8K ~ 300K. We analyzed an electrical conduction mechanism of the OLEDS using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling. In the temperature range above 150k, the conduction mechanism could be explained by space charge limited current from the inversely proportional temperature dependence of exponent m. The characteristic trap energy is found to be about 0.15ev. At low temperatures below 150k, the Fowler-Nordheim tunneling conduction mechanism is dominant. We have obtained a zero field barrier height to be about 0.6~0.8eV.

Transient Characteristics of a Transformer Type SFCL Applying the Superconductor and the Normal-conductor into the Secondary Winding (초전도체 및 상전도체의 변압기 2차측 적용에 따른 변압기형 SFCL 특성 비교)

  • Jung, Byung-Ik;Choi, Hyo-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.5
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    • pp.873-877
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    • 2016
  • This paper proposed the structure that applied superconductors to the neutral line of a transformer and applied the normal conductors to the third line. The superconductor applied to the neutral line of a transformer limited the peak value of initial fault current, while the normal conductor finally limited the fault current. In order to secure the operating reliability of transformer type Superconducting Fault Current Limiter (SFCL) of previously proposed structure, we analyzed the operating characteristics according to the fault types. We tested a line-to-ground fault and a line-to-line fault. As a result of the experiment, all the faults showed that the superconductor stably limited the peak-value of initial fault current. Also, the normal conductor finally limited the fault current. Based on this research results, We thought that if the structure of inserting superconductor into the neutral line is applied to the real system, it could improve the reliability and stability of the power system.

Design of the PMOLED Driver IC improving the terminal current offset (출력 전류 불균일을 개선한 PMOLED 구동 IC 설계)

  • Kim, Jung-Hak;Chung, Ho-Ryun;Ha, Chung-Gyun;Lee, Joo-Chul;Lee, Wook;Lee, Hwan-Woo;Yang, Hwi-Chan
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.995-996
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    • 2006
  • This paper presents a design of the PMOLED(Passive Matrix Organic light emitting diodes) driver IC improving the terminal current offset. The proposed methods are improving the design of the usual data output circuit. This methods can be avoidance brightness non-uniformity problem.

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Electrical Conduction Mechanism in ITO/$Alq_3$/Al device structure (ITO/$Alq_3$/Al 소자 구조에서 전기 전도 메카니즘)

  • Chung, Dong-Hoe;Kim, Sang-Keol;Lee, Dong-Gyu;Lee, Joon-Ung;Hur, Sung-Woo;Jang, Kyung-Uk;Lee, Won-Jae;Song, Min-Jong;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.531-532
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    • 2005
  • We have used ITO/$Alq_3$/Al structure to study electrical conduction mechanism in $Alq_3$ based organic light emitting diode. Current-voltage characteristics were measured at room temperature by varying the thickness of $Alq_3$ layer from 60 to 400nm. We were able to prove that there are three different mechanism depending on the applied voltage; Ohmic, SCLC (space-charge-limited current). and TCLC (trap-charge -limited current) mechanism.

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Study on Transient Current Limiting Operational Characteristics of Transformer Type SFCL with Two Peak Current Limiting Function (두 번의 피크전류제한 기능을 갖는 변압기형 초전도한류기의 과도전류제한 동작 특성 연구)

  • Han, Tae-Hee;Lim, Sung-Hun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.8
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    • pp.499-504
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    • 2016
  • In this paper, we analyzed the operational characteristics of the fault current limiting according to the amplitude of the fault current for the transformer type superconducting fault current limiter (SFCL). If the fault current happens, the superconducting element connected to the secondary coil is occurred quench and the fault current is limited. When the larger fault current occurs, the superconducting element connected to the third coil is occurred additional quench and the peak fault current is limited. We found that the fault current can be more effectively controlled through the analysis of the fault current limiting and the short-circuit tests.

A Study on Characteristics of Flux-offset-type Fault Current limiter according to Initial fault current

  • Jung, Byungik;Hwang, Junwon;Choi, Hyosang
    • International Journal of Internet, Broadcasting and Communication
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    • v.7 no.2
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    • pp.117-122
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    • 2015
  • Our research team proposed a flux-offset type fault current limiter as a new limiter. The flux-offset type fault current limiter uses a fault current limit technology based on the flux offset principle of the primary and secondary windings of a transformer. Stable fault current limit characteristics were achieved through a preliminary study. However, it was discovered that the initial fault current was not limited. Therefore, in this paper, a high-speed interrupter and a superconducting element were separately applied to the secondary winding of the flux-offset type fault current limiter and the operating characteristics were comparatively analyzed. In the experiment, when the superconducting element was applied to the secondary winding of the transformer, the initial fault current was limited while the limitation in the operation time was further shortened.

Tests of Inductive High-Tc Superconducting Fault Current Limiter with an Air-Gap (공극형 고온초전도한류기의 특성실험)

  • Joo, Min-Seok;Lee, Chan-Ju;Chu, Yong;Ko, Tae-Kuk
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.181-183
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    • 1996
  • A novel model of an inductive superconducting fault current limiter with an inductive superconducting fault current limiter with the air-gap core was fabricated and tested. If its impedance is not high enough to limit the fault current, then destructive damage occurs in the power system. We attained a magnetic saturation under higher current by an effective air gap introduced in the core. The fault current was successfully limited to two times as much as the nominal current at a 60 Hz source having an effective voltage of 70 V. The fault current flowing under such conditions can be limited to a desired value without any fault current peak within 1/4 cycles.

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Electrical Conduction Mechanism and Equivalent Circuit Analysis in $Alq_3$ based Organic Light Emitting Diode ($Alq_3$에 기초한 유기 발광 소자에서 전기전도특성과 등가회로분석)

  • Chung, Dong-Hoe;Shin, Cheol-Gi;Lee, Dong-Gyu;Lee, Joon-Ung;Lee, Suk-Jae;Lee, Won-Jae;Jang, Kyung-Wook;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.103-106
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    • 2004
  • We have studied a conduction mechanism and equivalent circuit analysis in $Alq_3$ based Organic Light Emitting Diode. The conduction mechanism in organic light emitting diode can be classified into three regions; ohmic region, space-charge-limited current (SCLC) region and trap-charge-limited current (TCLC) region depending on the region of applied voltage. Equivalent circuit model of organic light emitting diode can be established using a parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance $R_s$.

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