Electric Flux Approach for Surface Charges on Current Carrying Conductor

Lee Yeon Ho 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

When a straight conductor of fnite length is connected to a battery, the positive and negative charges on the upper and lower plates of the conductor induce an electric feld and a current in the conductor. In the conventional method, it is assumed that the internal electric feld is uniform as steady current fows in the conductor. However, the electric feld is induced by electric charges but not by currents. A steady current can fow in a wire when guided by charge accumulated on the surface of the conductor. Although the existence of surface charge has been confrmed in several studies, an analytical approach to determine the surface charge distribution was successful only when the conductor was considered infnitely long. Numerical methods were used to compute the electric fux incident on the conductor surface and to determine the surface charge that balances the incoming electric fux. However, the relationship between the incoming electric fux and the surface charge has not been established in a closed form. In this study, the conduction current is considered to be the relaxation of the electrode and surface charges and is treated as the sum of the electric fuxes entering and leaving the conductor surface. The relationship between the incoming electric fux and surface charge is obtained in a closed form by applying the continuity equation and boundary conditions for the electric feld at the interface between two dissimilar materials. This relationship is applicable to any interface, including conductor-conductor and lossy dielectric-dielectric interfaces. A two-dimensional model of a current-carrying wire is developed using slab conductors to numerically compute the surface charge densities, electric felds, and equipotential surfaces inside and outside the conductor. Our results show that the charge peaks at the corners of the conductor and at the point where two dissimilar conductors meet.

A novel slippery liquid infused porous aluminum conductor with excellent corrosion resistance in simulated marine atmosphere

Tao Zhu,Yuan Yuan,Qi Yu,Huiying Xiang,Xu Dai,Guoyong Liu,Ruijin Liao 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

The overhead aluminum conductors are prone to corrosion, especially in areas with marine climates,which interferes with the safe operation of the power system. Herein, slippery liquid infused porous surface(SLIPS) conductors were successfully prepared on pure aluminum (Bare) conductors by anodizingand infusion of silicone oil. The corrosion resistance of the conductors during 30 days of salt spray corrosionand 7 days of energized conditions was studied. The results indicated that the corrosion of theBare and anodic aluminum oxide (AAO) conductors was more severe under energized (alternating current(AC) and direct current (DC)) conditions. The exacerbation of corrosion by DC energization wasremarkably higher than that of AC energization. The AAO conductor showed better corrosion resistancethan the Bare conductor, which was attributed to the porous alumina retarding the medium intrusion. Due to the barrier effect provided by the lubricant layer, the SLIPS conductor always presented excellentcorrosion resistance than the Bare and AAO conductors. In addition, the mechanical and electrical propertiesof the SLIPS conductor were comparable to the Bare conductor and could satisfy the basic requirementsfor practical applications. The prepared SLIPS conductors offer great application prospects for thecorrosion protection of aluminum conductors.

영구전류모드 운전을 위한 coated conductor의 가공 및 자석 제조

이희균,김재근,이선왕,김우석,이승욱,최경달,홍계원,고태국,Lee, Hee-Gyoun,Kim, Jae-Geun,Lee, Sun-Wang,Kim, Woo-Seok,Lee, Seung-Wook,Choi, Kyung-Dal,Hong, Gye-Won,Ko, Tae-Kuk 한국초전도학회 2006 Progress in superconductivity Vol.7 No.2

Coated conductors suitable for the fabrication of persistent mode high $T_c$ magnets are suggested and the fabrication method of persistent mode magnets using coated conductor are demonstrated. Persistent current was observed in a small piece of coated conductor. Closed loop of coated conductor with a diameter of around 1 em was successfully prepared and was cooled with a magnetic field of about 500 Gauss in order to induce supercurrent. Coated conductor with a $I_c$ of 100 A/cm-width was used for the preparation of closed loop of coated conductor. Persistent current was confirmed by measuring the magnetic field generated from closed loop of coated conductor by using Gauss meter. Magnetic field of 4.4 Gauss was detected from the supercurrent of closed loop of coated conductor. It shows that superconducting joint of coated conductor is not a prerequisite for the construction of persistent mode magnets. It is thought that this work opens the possibility to use coated conductor for the construction of persistent mode high $T_c$ magnets for MRI, NMR and magnetic separation applications.

고강도 저손실 가공송전선의 개발(I) - 기계적 특성

김병걸,김상수,박주환,Kim, Byung-Geol,Kim, Shang-Shu,Park, Joo-Hwan 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12

New conductor is developed by using high strength nonmagnetic steel(NM) wire as the core of overhead conductor. This conductor is called ACNR overhead conductor(Aluminum Conductor Nonmagnetic Steel Reinforced). Formed by the combination of aluminum alloy wire and high strength nonmagnetic steel wire, it has about the same weight and diameter as conventional ACSR overhead conductor. To enhance properties beneficial in an electrical and mechanical conductor during the process of high strength nonmagnetic steel wire, we made a large number of improvements and modifications in the working process, aluminum cladded method, and other process. ACNR overhead conductor, we successfully developed, has mechanical and electrical properties as good as or even better than conventional galvanized wire. Microstructure of raw material M wire was austenite and then deformed martensite after drawing process. Strength at room temperature is about $180kgf/mm^2\~200kgf/mm^2$. NM wire developed as core of overhead conductor shows heat resistant characteristics higher than that of HC wire used as core of commercial ACSR overhead conductor, Strength loss was not occur at heat resistant test below $600^{\circ}C$. Fatigue strength of vibration fatigue is about $32kgf/mm^2\~35kgf/mm^2$ and that of tension-tension fatigue is $90kgf/mm^2\~120kgf/mm^2$ which is $50\~65\%$ of tensile strength.

인하도선시스템 시설에서의 문제점과 대책

이복희,이동문,강성만,엄주홍,정동철,이승칠,안창환 한국조명전기설비학회 2002 조명·전기설비학회논문지 Vol.16 No.4

내본 논문에서는 뇌서지에 의해서 발생하는 컴퓨터를 비롯한 전자기기의 장해에 대한 보호대책을 제안하기 위해서내 국내의 뇌보호설비에 대한 규격과 지침에 대한 기술적인 문제점을 분석하였다. 인하도선의 설치방법에 따른 인하도선과 인입용 금속관을 통하여 흐르는 전류사이의 관계를 검토하였으며, 인하도선계에 미치는 표피효과의 영향을 평가하는 실험을 수행하였다. 그 결과 인하도선을 인입용 금속관에 전기적으로 접속한 때 인하도선과 금속관은 하나의 도체로 작용하며, 표피효과와 쵸킹효과 때문에 뇌격전류는 인하도선보다도 금속관을 통하여 훤씬 많은 전류가 흘렀다. 따라서 뇌격전류에 의한 인하도선의 전위상승으로 야기되는 정전유도와 측면방전 등의 악영향을 억제하기 위해서는 인하도선을 인입용 금속관과 건물의 철골 구조체에 전기적으로 접속하는 것이 매우 효과적이다. This paper describes the technical issues of the domestic standard and guideline for lightning protection systems in order to propose the countermeasures in damage of computer and electronic equipments due to lightning surges. The relationship between the current flow in the down conductor and the current flow in the steel conduit surrounding the down conductor was investigated as a function of the installation method of down conductors. Also the experiments were conducted to evaluate the influences of the skin effect on the down conductor systems. As a result, when the down conductor were bonded to the steel conduit, the down conductor and the steel conduit act as one conductor, so much mure lightning current flows in the steel conduit than in the copper down conductor because of the skin effect and choking effect. Therefore to reduce the adverse effects such as the electrostatic induction and side flashes caused by the potential rise of down conductors due to lightning currents, it is extremely effective to bond the down conductor to the steel conduit and steel frame of structures.

Aerodynamic Characteristics of Iced 8-bundle Conductors under Different Turbulence Intensities

Mengqi Cai,Qian Xu,Linshu Zhou,Xiaohui Liu,Hanjie Huang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11

Iced conductor motion is induced by the aerodynamic instability. The aerodynamic characteristics of iced bundle conductors in turbulent flow are significantly different from that in uniform flow. The aerodynamic coefficients of iced 8-bundle conductors’ segment models under different turbulence intensities flow are measured by the wind tunnel experiment. Furthermore, the aerodynamic coefficients of each crescent- and sector-shape iced 8-bundle conductors under different turbulence intensities flow and ice thicknesses are obtained. The wind tunnel test results indicate there have obvious difference between aerodynamic characteristics of bundle conductors in turbulent flow and that in uniform flow. Then, key parameters, such as turbulence intensity, ice thickness and ice shape have significant influences on aerodynamic coefficients of each sub-conductors. Differences exist among aerodynamic coefficients of crescent-shape and sector-shape iced 8-bundle conductors. Finally, the galloping coefficients of iced 8-bundle conductors are discussed. The wind tunnel experiment results can offer useful reference resources for the comprehensive analysis of galloping of iced bundle conductors and their prevention techniques.

Backed Conductor의 Center-Elimination을 통한 향상된 방향성을 갖는 CPW 방향성 결합기의 설계

박정훈,이창언,최경민,신철재 한국전자파학회 2003 한국전자파학회논문지 Vol.14 No.12

본 논문에서는 finite-extent backed conductor를 가지는 CPW(Coplanar waveguide) 방향성 결합기에서, 방향성의 향상을 위해 backed conductor의 가운데 부분을 적절한 길이로 제거하는 보상구조를 제안하였다. backed conductor의 가운데 부분이 적절한 길이를 가지고 제거될 경우, 결합기의 가운데 부분에서 기 모드의 유효 유전율이 크게 감소하여 전기적 길이가 달라지므로, 우 모드와 기 모드의 위상속도가 동일하게 인식된다. 따라서 결합기의 방향성은 향상이 되며, 이때 제거된 backed conductor의 적절한 길이는 결합기의 기 모드와 우 모드의 관계로부터 구하여질 수 있다. 이 보상 구조가 효과적임을 보이기 위해 1 GHz의 중심주파수를 가지는 보통의 결합도를 갖는 CPW 방향성 결합기를 설계하였으며, 기존의 구조에 비해 모의실험과 측정에서 각각 36 dB, 20 dB이상 개선된 우수한 방향성특성과 함께 우수한 정합특성을 가짐을 확인하였다. In this paper, we demonstrate that the directivity of the CPW(Coplanar Waveguide) directional coupler with finite-extent backed conductor is enhanced by eliminating center region of backed conductor appropriately. If the backed conductor is removed at center region of couplers, the couplers have two backed conductors. If effective odd mode dielectric constant is decreased at center region, the electrical length for odd mode is changed and phase velocity is same at the directional couplers. Hence, directivity is improved. The eliminated length is solved by an odd and even mode analysis. The designed moderate CPW directional coupler with the proposed compensation structure has excellent directivity and matching characteristic at center frequency in simulation and measurement.

고강도 저손실 가공송전선의 개발(II) - 전기적 특성

김병걸,김상수,박주환,Kim, Byung-Geol,Kim, Shang-Shu,Park, Joo-Hwan 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12

New conductor is developed by using high strength nonmagnetic steel(NM) wire as the core of overhead conductor This conductor is called ACNR overhead conductor(Aluminum Conductor Nonmagnetic Steel Reinforced). Formed by the combination of aluminum alloy wire and high strength nonmagnetic steel wire, it has about the same weight and diameter as conventional ACSR overhead conductor. To enhance properties beneficial in an electrical and mechanical conductor during the Process of high strength nonmagnetic steel wire, we made a large number of improvements and modifications in the working process, aluminum cladded method, and other process. ACNR overhead conductor, we successfully developed, has mechanical and electrical properties as good as or even better than conventional galvanized wire. Microstructure of raw material NM wire was austenite and then deformed martensite after drawing process. Strength at room temperature is about $180kgf/mm^2\~200kgf/mm^2$. The conductivity at 0.78 mm thickness of Aluminum cladded M wire is about $7\%$ IACS higher than $20\%$IACS of HC wire used as core of commercial ACSR overhead conductor. The corrosion resistance is about 3 times higher than that of HC wire.

Aerodynamic force characteristics and galloping analysis of iced bundled conductors

Lou, Wenjuan,Lv, Jiang,Huang, M.F.,Yang, Lun,Yan, Dong Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.2

Aerodynamic characteristics of crescent and D-shape bundled conductors were measured by high frequency force balance technique in the wind tunnel. The drag and lift coefficients of each sub-conductor and the whole bundled conductors were presented under various attack angles of wind. The galloping possibility of bundled conductors is discussed based on the Den Hartog criterion. The influence of icing thickness, initial ice accretion angle and sub-conductor on the aerodynamic properties were investigated. Based on the measured aerodynamic force coefficients, a computationally efficient finite element method is also implemented to analyze galloping of iced bundled conductors. The analysis results show that each sub-conductor of the bundled conductor has its own galloping feature due to the use of aerodynamic forces measured separately for every single sub-conductors.

Aerodynamic force characteristics and galloping analysis of iced bundled conductors

Wenjuan Lou,M.F. Huang,Jiang Lv,Lun Yang,Dong Yan 한국풍공학회 2014 한국풍공학회지 Vol.18 No.2

Aerodynamic characteristics of crescent and D-shape bundled conductors were measured by high frequency force balance technique in the wind tunnel. The drag and lift coefficients of each sub-conductor and the whole bundled conductors were presented under various attack angles of wind. The galloping possibility of bundled conductors is discussed based on the Den Hartog criterion. The influence of icing thickness, initial ice accretion angle and sub-conductor on the aerodynamic properties were investigated. Based on the measured aerodynamic force coefficients, a computationally efficient finite element method is also implemented to analyze galloping of iced bundled conductors. The analysis results show that each sub-conductor of the bundled conductor has its own galloping feature due to the use of aerodynamic forces measured separately for every single sub-conductors.