• Title/Summary/Keyword: Down conductor

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The Control of the Magnetic Field around Down Conductors (인하도선 주변에서 발생하는 자장의 억제)

  • Lee, Bok-Hee;Kang, Sung-Man;Lee, Seung-Chil;Eom, Ju-Hong;Lee, Kyoung-Ok
    • Proceedings of the KIEE Conference
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    • 2001.11a
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    • pp.216-218
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    • 2001
  • This paper deals with the control of magnetic field around the down conductor of lightning protection systems. The magnetic field strength in the vicinity of down conductor is shown to drop off rapidly with distance from the down conductor and is reversely proportional to the number of down conductor. Also the magnetic field strength is decreased in the structures as the down conductor is installed with the symmetrical arrangement, and it is zero at the center of symmetry. The magnetic field strengths for the symmetrical arrangement of two down conductors are less than one half compared with that for a down conductor. A proper arrangement of down conductor can reduce or cancel the magnetic field in a restricted place where information-oriented and computerized facilities are densely installed.

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Problems and Countermeasures in Installation of Down Conductor Systems (인하도선시스템 시설에서의 문제점과 대책)

  • 이복희;이동문;강성만;엄주홍;정동철;이승칠;안창환
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.4
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    • pp.38-45
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    • 2002
  • 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.

Experimental Verification on the Use of Steelwork as a Down-Conductor in Lightning Protection System (인하도선으로 활용하기 위한 철근콘크리트구조물의 전기 및 기계적 소요 특성에 대한 실험적 검증)

  • Lee, Ki-Hong
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.9
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    • pp.94-99
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    • 2011
  • This paper verified the characteristics of electrical continuity and mechanical strength of steelwork required to use it as a down-conductor in lightning protection system. It was proven that the steelwork in reinforced concrete apartment has an excellent electrical continuity with low resistance(less than 0.2[${\Omega}$].). But it was confirmed that a poor connection between two reinforcement bars can easily cause serious damages of the concrete even with the impulsive current of 50[kA], 10/350[${\mu}s$]. These results of experiments mean that the additional measures are necessary in using the steelwork as the down-conductor of the lightning protection system.

Distributions of the Magnetic Flux Density Near Down-Conductors Due to Various Impulse Currents (임펄스전류에 의한 인하도선 주위에서 자속밀도의 분포)

  • 이복희;장근철;이수봉;강성만;이승칠
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.2
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    • pp.109-115
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    • 2004
  • This paper deals with the behaviors of magnetic flux density near down-conductors by lightning currents. The background on the principle of magnetic flux density measurements using the RL self-integrating magnetic field sensor was described. The magnetic flux density measuring device consisting of RL self-integrating magnetic field sensor and differential amplifier was designed and fabricated. The frequency bandwidth of the magnetic flux density measuring system ranges from 200 Hz to 300 KHz and the response sensitivity was 0.126 $\mu$T/㎷ The distributions of the magnetic flux density near down-conductors due to impulse currents with various rise times were analyzed as a parameter of the bonding conditions and materials of conductor and wiring conduits. The magnetic flux density due to impulse currents was inversely proportional to the distance between the down-conductor and measuring point. The amplitude of the magnetic flux density for PVC Pipe with down-conductor was 72 $\mu$T/㎷ at the distance of 1m and was higher than for steel conduits and coaxial cable. Finally the magnetic flux density is increased with increasing the di/dt it and oscillation frequency of lightning currents in this experimental ranges.

Effects of Length of Down Conductor on Transient Ground Impedance (인하도선 길이에 따른 과도접지임피던스 특성)

  • Lee, B.H.;Jeong, D.C.;Lee, S.B.;Lee, T.H.;Jung, H.U.;Lee, K.S.;Lee, S.C.
    • Proceedings of the KIEE Conference
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    • 2005.07c
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    • pp.2235-2237
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    • 2005
  • This paper presents the transient impedance behaviors of grounding systems to lightning impulse current. The potential rise and effective impulse ground impedance of the test grounding electrodes were measured as a function of the rise time of impulse currents and lengths of down conductor. The transient ground impedances strongly depend on the configuration and size of grounding electrodes, the impulse current shapes and lengths of down conductor, and the inductance of reduce of grounding electrode inductance is an important factor to improve the transient ground impedance.

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Effective Installation Methods of Down Conductors in Lightning Protection Systems (뇌보호시스템에서 인하도선의 효과적인 설치기법)

  • 이복희;엄주홍;이승칠;강성만
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.4
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    • pp.8-14
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    • 2002
  • A modern lightning protection system is required to eliminate the risks such as electrical shocks and damages of structures, electrical and electronic equipments due to lightning. However, the conventional lightning protection systems play and important role in protecting persons and structures only. Thus an effective lightning protection system is indispensable today in computer, information and communication facilities and etc. The mafor objective of this paper is to develop the technology to protect electronics and computerized facilities against lightning-caused overvoltages. The study is oriented on the control of the potential rise of down conductors with the type and installation method of down conductors. As a result, to reduce side flashes and hazards caused by the potential rise of down conductor due to lightning current, the coaxial cable with a low characteristic impedance and high insulation level is suitable for a down conductor. In particular it is extremely effective to bond down conductors to the steel supporter, metal raceways and steel frame of structures.

Potential Rises of Down-conductor for Lightning Protection System according to Establishment Conditions (뇌보호설비용 인하도선의 설치조건에 따른 전위상승)

  • Lee, Bok-Hee;Kang, Sung-Man;Lee, Seung-Chil;Lee, Dong-Mun;Ahn, Chang-Hwan
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1724-1726
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    • 2001
  • This paper deals with the characteristics of the potential rises of down-conductor due to lightning surge currents. Direct lightning strikes can cause high impulse currents to the lightning protection system(LPS) of a building. These high impulse currents have the front time as short as 1[${\mu}s$]. In this case, the induced voltages caused in a closed circuit inside the building can be very high and cause damage or submit people to electric hazard. So, the LPS has to be designed to ensure safety condition to person and acceptable levels of induced voltages to the electrical and electronic equipments. The results of the potential rises related to the bonding conditions between the grounding conductor and metal raceway and the type of down-conductors are introduced.

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Considerations in Down-conductor System and Earth-termination System Design of Apartments (공동주택에서의 인하도선시스템과 접지시스템 설계에 대한 고찰)

  • Lee, Ki-Hong;Lee, Jae-Bok;Chang, Sug-Hun
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2006.05a
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    • pp.54-58
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    • 2006
  • This paper deals with primary consideration in down-conductor system and earth-termination system design of apartments. For down-conductor system, steelworks within reinforced concrete apartment structures have the electrical continuity, however, lashing is not suitable for lightning-current-carrying connections. So this paper suggest that the additional dedicated conductors should be installed and they are should be lashed to the reinforcement steel. Also this paper suggested the foundation earth electrode and global earth system as the earth-termination system of the apartments. But perfect bonding system is essential in lightning protection system to avoid life hazard and to protect electronic equipments.

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Effects of the Length of Down Conductors on Transient Ground Impedances (인하도선의 길이가 과도접지임피던스에 미치는 영항)

  • Lee, Bok-Hee;Lee, Su-Bong;Jeong, Dong-Cheol
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.4
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    • pp.72-77
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    • 2006
  • This paper presents the transient impedance behaviors according to the length of down conductors of grounding systems to lightning impulse currents. The potential rise and effective impulse ground impedance of the deeply-driven ground rod and grounding grid subjected to the impulse currents were measured and analyzed as a function of the rise time of impulse currents and lengths of down conductor. The transient ground impedances strongly depend on the configuration and size of grounding electrodes, the waveform of impulse currents and the length of down conductors, and the installation methods reducing the inductance of down conductors are an important factor to decrease the transient ground impedances.

current profiles in a coated conductor with transport current (외부 전류가 흐를 때 초전도 선재에서의 전류 분포)

  • Yoo, Jae-Un;Lee, Sang-Moo;Jung, Ye-Hyun;Lee, Jae-Young;Youm, Do-Jun
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.3
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    • pp.1-4
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    • 2007
  • The current profiles in a coated conductor with transport current were calculated using an iterative inversion method from the data of the magnetic flux density profiles measured. The applied current was increased from 0 to 60 A by 10A step and decreased down to -60A by 20A step. The magnetic flux profiles were measured at a distance of 400 mm above the surface of the coated conductor using a scanning hall probe method. The current profiles calculated were very different from the Bean model: current density profile is not a constant in the critical region. However the aspect of the change of the current and magnetic flux density profiles in the case of decreasing applied current are similar to the theoretical calculations in Brandt's paper.