• Title/Summary/Keyword: electrical resistance method

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Trust Analysis of Ground Resistance Measurements by the Substitute Auxiliary Electrode (대체 보조전극을 이용한 접지저항 측정 신뢰성 분석)

  • Lee, Sang-Ick;Yoo, Jae-Geun;Jeon, Jeong-Chay;Jeon, Hyun-Jae
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.56 no.2
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    • pp.109-114
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    • 2007
  • This paper summarize about the auxiliary electrode measured a ground resistance. The method to measure a ground resistance is the fall-of-potential method to using an auxiliary electrode. And an auxiliary electrode must be set up on the ground. Today it is so difficult to set up the auxiliary electrode on the ground because of many concrete building and many paved roads. So this paper is regarding a trust analysis of the ground resistance measurement by the substitute auxiliary electrode. It substituted a iron structure around the building, a neutral line multiplex ground to earth, a wire net for auxiliary electrode. This information is confirmed bv compared with the measurement value.

Improvement of Detailed Fault Point Decision Using EMTP Analysis of Search Coil Method for HVDC Cables (Search Coil법의 EMTP 분석을 통한 HVDC 케이블 상세 고장지점 판정 정확도 개선)

  • Jung, Chae-Kyun;Park, Jin-Woo;Yang, Byeong-Mo;Kang, Ji-Won;Lee, Jong-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.9
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    • pp.1656-1662
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    • 2011
  • In a previous paper, the EMTP modeling technique using search coil test is established through various transient analysis including system grounding condition and grounding resistance for HVDC submarine cables. It was also proved by comparison with real test results. Based on this EMTP modeling technique, in this paper, it will be applied for modeling of ${\pm}180kV$ real HVDC submarine system(Jeju~Haenam). This paper variously analyses the effects of fault resistance including the resistance between core and sheath, the resistance between sheath and amore and the resistance between amore and sea water through EMTP modeling of search coil method. The results can contribute to the accuracy of detailed fault point prediction of search coil test for HVDC submarine cables.

A Study on the Measurement of Grounding Resistance based on the Earth Surface Potential Analysis (지표면전위 해석에 의한 접지저항 측정기법에 관한 연구)

  • 윤장완;안용호;정길조;한병성
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.4
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    • pp.117-123
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    • 2002
  • Measurement of ground resistance is the basic and important procedure to evaluate the proriety of grounding systems performance. In the field, however, it is not an easy task to measure ground resistance accurately, because locating a right position of zero potential for accurate GPR(Ground Potential Rise) measurement is very difficult, especially in case of a grounding electrode with large dimension. In this paper, the estimation method of ground resistance by analysing earth surface potential distribution around the grounding electrodes has been described.

On-line Identification of Rotor Resistance for Sensorless Induction Motors Using Variable Rotor Flux (가변 회전자 자속 지령에 의한 센서리스 유도전동기의 회전자 저항 실시간 동정)

  • Lee Zhen-Guo;Jeong Seok-Kwon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.2
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    • pp.101-109
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    • 2005
  • The newly developed speed sensorless control scheme is proposed to estimate both motor speed and rotor resistance simultaneously using variable rotor flux. The rotor flux is given as sinusoidal waveform with an amplitude and a frequency without affecting precise torque control. Especially the proposed method makes the simultaneous estimation of rotor resistance and speed with high precision even though at the low speed area including a few rpm. Moreover, on-line identification of rotor resistance can be performed simply without calculating troublesome trigonometric functions and complicated integral computation. Therefore, the proposed system can be accomplished by using very cheap microprocessors for several applications. The results of the numerical simulations and experiments demonstrate that this method is effective to estimate the speed and on-line identification of rotor resistance for sensorless induction motors.

The 4-channel Multiple Contact Resistance Measurement Systems using MQTT Broker Server for AC 22.9 kV COS/Lightning Arrester (MQTT 브로커 서버를 이용한 AC 22.9 kV 차단기/피뢰기의 4-채널 다중 접촉저항 측정 시스템)

  • Ra-Yun Boo;Jung-Hun Choi;Myung-Eui Lee
    • Journal of Advanced Navigation Technology
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    • v.27 no.2
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    • pp.203-208
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    • 2023
  • In this study, we propose a method to improve the precision of contact resistance measurement circuits using constant current method and voltage drop method, and implement a dashboard that monitors the measured data of contact resistance measurement systems through MQTT broker server. The contact resistance measurement system measures the resistance value and transmits the measured value to the MQTT broker server using wireless communications. This developed dashboard uses Node-RED and Node-RED-Dashboard to receive the resistance values of up to four contact resistance measurement systems and show them to user's monitor screen. Users can manage multiple measurement data using a single dashboard and easily interface with other devices through the MQTT broker server. Through the experimental results from real data measurements, the relative standard deviation about precision is improved to average 40.37% and maximum 64.73% respectively.

Role of edge patterning and metal contact for extremely low contact resistance on graphene

  • Jo, Seo-Hyeon;Park, Hyung-Youl;Park, Jin-Hong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.294.2-294.2
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    • 2016
  • Graphene, a sigle atomic layered structure of graphite, has drawn many scientific interests for attractive future electronics and optoelectronics beyond silicon-based technology because of its robust physical, optical, and electrical properties. But high metal-graphene contact resistance prevents the successful integration of high speed graphene devices and circuits, although pristine graphene is known to have a novel carrier transport property. Meanwhile, in the recently reported metal-graphene contact studies, there are many attempts to reduce the metal-graphene contact resistance, such as doping and one-dimensional edge contact. However, there is a lack of quantitative analysis of the edge contact scheme through variously designed patterns with different metal contact. We first investigate the effets of edge contact (metal-graphene interface) on the contact resistance in terms of edge pattern design through patterning (photolithography + plasma etching) and electral measurements. Where the contact resistance is determined using the transfer length method (TLM). Finally, we research the role of metal-kind (Palladium, Copper, and Tianium) on the contact resistance through the edge-contacted devices, eventually minimizing contact resistance down to approximately $23{\Omega}{\cdot}{\mu}m$ at room temperature (approximately $19{\Omega}{\cdot}{\mu}m$ at 100 K).

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A Study on the Limited Rate Power Capacity for Applications for Precision Passive Devices Based on Carbon Nanotube Materials (탄소나노튜브 소재의 정밀 수동소자 적용을 위한 한계 정격전력 용량에 관한 연구)

  • Lee, Sunwoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.3
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    • pp.269-274
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    • 2022
  • We prepared carbon nanotube (CNT) paper by a vacuum filtration method for the use of a chip-typed resistor as a precision passive device with a constant resistance. Hybrid resistor composed of the CNT resistor with a negative temperature coefficient of resistance (T.C.R) and a metal alloy resistor with a positive T.C.R could lead to a constant resistance, because the resistance increase owing to the temperature increase at the metal alloy and decrease at the CNT could counterbalance each other. The constant resistance for the precision passive devices should be maintained even when a heat was generated by a current flow resulting in resistance change. Performance reliabilities of the CNT resistor for the precision passive device applications such as electrical load limit, environmental load limit, and life limit specified in IEC 60115-1 must be ensured. In this study, therefore, the rated power determination and T.C.R tests of the CNT paper were conducted. -900~-700 ppm/℃ of TCR, 0.1~0.2 A of the carrying current capacity, and 0.0625~0.125 W of the rated power limit were obtained from the CNT paper. Consequently, we confirmed that the application of CNT materials for the precision hybrid passive devices with a metal alloy could result in a better performance reliability with a zero tolerance.

Effect of the Current Probe Position on Ground Resistance Measurement Using Fall-of-Potential Method (전위강하법에 의한 접지저항 측정에 미치는 전류보조전극의 위치의 영향)

  • Lee, B.H.;Eom, J.H.;Kim, S.W.
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1874-1876
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    • 2000
  • In this paper, the effects of the positions of the current probe on the measurements of the ground resistanc, and potential gradients with fall-of-potential method are described, and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of the measuring auxiliary probes. The ground resistance is calculated by applying the 61.8% lute using fall-of-potential method.

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A Decision Method for the Optimal Insertion Resistance of a Superconducting Fault Current Limiter with Reduction of an Asymmetric Fault Current (비대칭 고장전류 저감 기능을 갖는 초전도 한류기의 최적 저항 결정 방안)

  • Kim, Chang-Hwan;Kim, Kyu-Ho;Rhee, Sang-Bong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.1
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    • pp.57-63
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    • 2015
  • Fault currents characteristics contain decaying DC offset. First cycle peak value of fault currents is higher than steady-state fault current value. These characteristics can affect the operation of protective device. To reduce the asymmetric fault current, the method using a series connection of two hybrid-type Superconducting Fault Current Limiter(SFCL) components, an auxiliary SFCL and a main SFCL, has been proposed. The auxiliary SFCL limits the first half cycle fault current, while main SFCL limits the steady state fault currents. This paper proposed a decision method of the optimal insertion resistance of auxiliary and main SFCL components. To verify the effectiveness of proposed scheme, the various simulations are performed by using Electromagnetic Transient Program(EMTP).

An international Comparison Measurement of Silicon Wafer Sheet Resistance using the Four-point Probe Method

  • Kang, Jeon-Hong;Ying, Gao;Cheng, Yuh-Chuan;Kim, Chang-Soo;Lee, Sang-Hwa;Yu, Kwang-Min
    • Journal of Electrical Engineering and Technology
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    • v.10 no.1
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    • pp.325-330
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    • 2015
  • With approval from the Asia Pacific Metrology Program Working Group on Materials Metrology (APMP WGMM), an international comparison for sheet resistance standards for silicon wafers was firstly conducted among Korea Research Institute of Standards and Science (KRISS) in Korea, CMS/ITRI in Taiwan, and NIM in China, which are national metrology institutes (NMIs), from August 2011 to January 2012. The sheet resistance values of the standards are $10{\Omega}$, $100{\Omega}$, and $1000{\Omega}$; the measurement was conducted in sequence at KRISS, CMS/ITRI, NIM, and KRISS again using the four-point probe method with single and dual configuration techniques. The reference value for the measurement results of the three NMIs was obtained through averaging the values of the three results for each sheet resistance range. The differences between the reference value and the measured values is within 0.22% for $10{\Omega}$, 0.17% for $100{\Omega}$, and 0.12% for $1000{\Omega}$. Therefore, the international consistency for conducting sheet resistance measurements is confirmed within 0.22% through the APMP WGMM approved comparison.