• Title, Summary, Keyword: Grounding system

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A Study on Lightning Overvoltage Characteristics of Grounding Systems in Underground Distribution Power Cables

  • Jung, Chae-Kyun;Jung, Yeon-Ha;Kang, Ji-Won
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.628-634
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    • 2014
  • This paper investigates the transient characteristics of grounding systems used in under-ground distribution power cables. Recently, two kinds of grounding system are used for underground distribution cables in Korea. The first one is conventional multi-point grounding system, the other is newly proposed non-bundled common grounding system. The non-bundled common grounding system has an advantage the decreasing the power loss due to decrease of the shield circulation current. In this paper, the lightning overvoltage induced in neutral wire (in case of non-bundled common grounding system, overvoltage between opened neural wires and grounding in each phase) of these two kinds of grounding systems are estimated and compared by field tests and EMTP simulations. The EMTP simulation methods are firstly verified by comparison of measurement and simulation. Finally, the insulation level against lightning is expected by EMTP simulation results using verified model.

A CONCEPTUAL DESIGN FOR ELECTRICAL GROUNDING ARCHITECTURE OF KOREAN SPACE LAUNCH VEHICLE

  • Kim Kwang-Soo;Lee Soo-Jin;Ma Keun-Soo;Shin Myoung-Ho;Hwang Seung-Hyun;Ji Ki-Man;Chung Eui-Seung
    • Bulletin of the Korean Space Science Society
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    • pp.231-234
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    • 2004
  • Electrical grounding is defined as referencing an electrical circuit or a common reference plane for preventing shock hazards and for enhancing operability of the circuit and EMI control. In order to realize the best electrical grounding system of korean space launch vehicle, we should design the electrical grounding architecture of korean space launch vehicle of system-level at the earliest point in design procedure. To minimize the electrical grounding loop and the unnecessary electromagnetic interference or radiation among the electronic subsystems, we should establish the electrical grounding rules of the all electrical interfaces. The electrical interfaces among the electronic subsystems are generally classified into the electrical power and signal interfaces. Because of using the primary and secondary power system architecture in the korean space launch vehicle system such as the common space launch vehicle systems, we need to establish the electrical grounding rules between the primary and secondary power system. We also need to establish the electrical signal grounding interface rules among the electronic subsystems. In this paper, we will describe the grounding schemes of the common space launch vehicle system and propose a conceptual design for the electrical grounding architecture of korean space launch vehicle system.

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The Analysis of Ground Potential Rise for Shapes of Grounding Electrode Using Hemispherical Grounding Simulation System (반구형 접지모의시스템을 이용한 접지전극의 형상에 따른 대지전위상승의 분석)

  • Gil Hyoung-Jun;Choi Chung-Seog;Lee Bok-Hee
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.7
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    • pp.319-325
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    • 2005
  • In order to analyze ground potential rise of grounding system installed in buildings, the hemispherical grounding simulation system has been designed and fabricated as substantial and economical measures. Ground potential rise(GPR) has been measured and analyzed for shapes of grounding electrode using the system in real time. The system is apparatus to have a free reduced scale for conductor size and laying depth of a full scale grounding system and is constructed so that a shape of equipotential surface is nearly identified a free reduced scale with a real scale when a current flows through grounding electrode. The system was composed of a hemispherical water tank, AC Power supply, a movable potentiometer, and test grounding electrodes. The test grounding electrodes were fabricated through reducing grounding electrode installed in real buildings such as rod type, mesh grid type. When a mesh grid type was associated with a rod type, GPR was the lowest value. The proposed results would be applicable to evaluate GPR in the grounding systems. and the analytical data can be used 0 stabilize the electrical installations and prevent the electrical disasters.

Characteristics of Grounding Impedances of Carbon Compound Grounding Electrodes (탄소혼합물 접지전극의 접지임피던스의 특성)

  • Lee, Kang-Soo;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.5
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    • pp.54-60
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    • 2011
  • This paper presents characteristics of frequency-dependent grounding impedance and transient grounding impedance for the carbon compound grounding electrode used in the installation of computerized electronic equipment and lightning protection system. The frequency-dependent grounding impedances were measured by applying sinusoidal currents in the frequency range from 100 [Hz] to 10[MHz], and the transient grounding impedances were examined by subjecting the impulse current with the front-time between 1~80[${\mu}s$]. As a result, the ground resistance of the carbon compound grounding electrode is less than that of another type grounding electrodes. The transient grounding impedance is relatively low and the conventional grounding impedance is rather lower than the ground resistance. The frequency-dependent grounding impedance of the carbon compound grounding electrode is capacitive and the grounding impedance is decreased with increasing the frequency of injected currents. Therefore in the case that the carbon compound grounding electrode is jointly used with large-scaled grounding electrodes, it is possible to reduce the high frequency grounding impedance of the integrated grounding electrode system.

Characteristic Analysis elf Large Grounding system by Using Reduced Scale Model Method (축소모델 기법을 이용한 대규모 접지계의 특성분석)

  • 장석훈;이재복;명성호;조연규;김점식
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.3
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    • pp.162-167
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    • 2004
  • The scale model grounding systems to study the behavior of grounding system in uniform soils have been designed and fabricated. Constructional details and instrumentation have been discussed. To verify the accuracy of the results obtained from the experimental tests, they have been compared with computer calculation results. Also, in order to assess the effectiveness of bonding two grounding systems, grounding grid conductors which were downsized as a scale factor of 100:1 were analyzed by using the scale model method. A profile of GPR(Grounding Potential Rise) of each case was measured. The scale model grounding system presented in this paper can be valuable tool to analyze the ground potential profile and ground resistance of practical grounding system.

A Study on the Unification of the Grounding System of SeoulMetro (서울메트로 접지설비 표준화 방안 연구)

  • Kim, Gyun-Sig;Park, Han-Yeong;Back, Yu-Ho
    • Proceedings of the KSR Conference
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    • pp.1027-1036
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    • 2007
  • Since the opening of the Seoul Metro in 1974, the electric railway passengers have been increased rapidly and as the advanced equipments(OC,PSD) were introduced, additional power facilities were built in a limited area for the comfortable transportation environment. Present grounding system were built according to old Electric equipment standards and all the electric signal, communication and electronic equipments were built only for the purposes of protecting building structure, people and electronic equipments. Grounding system which was additionally built in the limited area caused problems with the building structure and it caused secondary damages when earth fault happens. One of the problems is grounding system of the building structure; grounding system does not work properly since grounding equipments are not separated from each other. So, existing grounding system needs to be improved and unified grounding system in the building should be established. The purposed of this study is to analyze all the grounding systems that had been built in different year and to establish unified grounding system of Seoul Metro.

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Assessment of Electrical Safety for Grounding System by Investigation on the Spot (현장조사에 의한 접지시스템의 전기안전성 평가)

  • Gil, Hyoung-Jun;Kim, Dong-Woo;Kim, Dong-Ook;Lee, Ki-Yeon;Kim, Hyang-Kon
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.361-364
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    • 2008
  • This paper deals with assessment of electrical safety for grounding system of buildings by investigation on the spot at construction site. The investigation was carried out for grounding method, grounding type, shape of grounding electrode, grounding for lightning protection system, continuity of steelwork in reinforced concrete structure and so on. The investigation on the spot was performed by researcher, engineer with over fifteen years of industry experience all over the country. As a result of investigation on the spot to 13 buildings, common grounding method was dominant. A new grounding system based on international standards includes unity grounding system, structure grounding utilizing steel reinforced concrete, equipotential bonding. use of surge protective device.

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The example of the Carbon Grounding Modules installation for PSD systems at a subway station, Seoulmetro (서울메트로 PSD장비 탄소접지모듈 설치 사례)

  • Chung, Young-Ki;Hyeon, Yong-Seop;Song, Byeong-Gwon;Kim, Yong-Hyeop
    • Proceedings of the KSR Conference
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    • pp.292-298
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    • 2008
  • Seoul Metro and Seoul Metropolitan Rapid Transit Corp. have started installing screen doors at subway platforms to improve the environment of subways and prevent passengers' accidents since 2006. They are still installing screen doors at subway platforms and Metropolitan Rapid Transit Corporations in other areas are also proceeding with installment of screen doors or making preparations for it. Grounding is necessary for installing PSD systems. In case that PSD grounding is connected with existing electrical equipment grounding system, it was decided to install separate grounding for safe operation of PSD system and passenger safety. However, it's very difficult to install new grounding at the subway station compound. A way to improve this condition is that we proceed with grounding by composing grounding station by carbon grounding rod. This paper will mainly deal with how to design and construct carbon ground rod, which has been applied to PSD system grounding since 2006, including its experimental examples. In this paper, ways to secure ground resistance below 5 ohms, which is resistance necessary for PSD grounding, and to compose grounding system were also discussed. Furthermore, a ground test to check the ability to fulfill a role of PSD grounding system was conducted. As a result of applying carbon grounding module, PSD system is being operated without any problem and the installment of PSD system will be continuously expanded in the future. It's also thought that a way to integrate grounding of each functional room which has been installed at the subway station compound and to arrange equipotential grounding should be reviewed and performed promptly.

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A Study on the Effective Surge Protection Method from Induced Lightning Surgeto Improve Isolate Grounding to Common Grounding (낙뢰 Surge 방호를 위한, 독립접지를 공통접지로 개선하는 효율적인 방법에 대한 연구)

  • Jeon, Hyung-Gu;Woo, Jea-Wook;Suh, Yong-Joon
    • Proceedings of the KSR Conference
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    • pp.1459-1467
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    • 2011
  • This paper proposes the effective method to improve the protection from induced lightning Surge by making common grounding from individual grounding. Common grounding under equipotential principle is more effective than individual grounding for lightning Surge protection, and so common grounding is indicated as international technical standard under the AC power supply system with neutral line. So, this paper is to propose the effective way of induced lightning Surge protection method for currently installed power supply system which has no neutral grounded line and individual grounding which are weak for lightning Surge protection. This proposal can improve the power supply system as has neutral line, and improve the grounding system to common grounding system. And also this paper proposes to make effective equipotential system with voltage variable shunting devices for lightning Surge protection.

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A Study on the Effective Surge Protection Method from Induced Lightning Surge to Improve Isolate Grounding to Common Grounding (낙뢰 Surge 방호를 위한, 독립접지를 공통접지로 개선하는 효율적인 방법에 대한 연구)

  • Woo, Jea-Wook
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.215-218
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    • 2013
  • This paper proposes the effective method to improve the protection from induced lightning surge by making common grounding from individual grounding. Common grounding under equipotential principle is more effective than individual grounding for lightning surge protection, and so common grounding is indicated as international technical standard under the AC power supply system with neutral line. So, this paper is to propose the effective way of induced lightning surge protection method for currently installed power supply system which has no neutral grounded line and individual grounding which are weak for lightning surge protection. This proposal can improve the power supply system as has neutral line, and improve the grounding system to common grounding system. And also this paper proposes to make effective equipotential system with voltage variable shunting devices for lightning surge protection.

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