• Journal of Electrical Engineering and Technology
• /
• v.9 no.2
• /
• pp.628-634
• /
• 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.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1459-1467
• /
• 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.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.215-218
• /
• 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.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.6
• /
• pp.298-306
• /
• 2002

We performed an safety evaluation on constructing of a common grounding system for electrical railway in view of its efficacy and technical fit. In order to compare the conventional grounding method, which has been individually conducted, with the common grounding with all ground wires connected in common to the counterpoise buried below the surface of the earth in parallel with rail, we set up scenarios with several cases of fault and load conditions in Chungbuk railway sections with the common grounding system. Based on models for railway conductors including the grounded system, line Parameters of railway power system are computed. The circuit model for power system with up and down lines, auto-transformers and railway substations is used to compute impedances of counterpoise and substation ground net. For each scenario with faults and operation conditions of railway, the induced potentials on signal and communication lines are also computed. It is shown that the common grounding for Chungbuk railway is superior experimentally to the conventional method in three respects: (1) the lower rail potentials during operation of railway in line, (2) the lower rail potentials for short-circuit faults between catenary and rail, and (3) the lower stress voltages on signal and communication lines for short-circuit or ground faults. The analysis results confirm that the grounding system for electric railway is required to be built by the common grounding and be evaluated on its safety in design.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.2
• /
• pp.191-197
• /
• 2008

This paper describes the effect of transient state in underground transmission and distribution lines installed together in the same tunnel. Two systems installed in the same tunnel are operated by the common grounding. This paper analyzed that how much one of the two kinds of systems influences the other systems during the transient state by EMTP/ATPDraw. Single line-to-ground fault and lightning surge were selected in transient state condition. These cases were simulated variously according to the variation of common grounding magnitude, fault location and lightning surge magnitude. It is evaluated that the analyzed results will be used for establishment and operating materials of common grounding in the same tunnel.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2149-2151
• /
• 1999

This paper describes the impulse response characteristics of the grounding systems in power utility system. Several regulations regarding to electric power equipments, services and managements require that the groundings of class 1 ($E_1$) and class 2 ($E_2$) must be connected at the common point in grounding systems. In addition, the grounding for arrester ($E_{LA}$), which belongs to the grounding of class 1, should be connected at the same point. However, there is no method and position of common-connection at anywhere. In this work, when the impulse current was injected through the grounding conductor for arrester, the investigations measuring and analyzing potential rises induced at the common connection point and other grounding conductors were conducted. The experiments were carried out in the conditions of the grounding conductor of 25m long and the near or remote common connection from ground electrode. The lightning impulse current was applied so as to simulate the on-set of arrester due to lightning and/or switching surges.

• Proceedings of the KIEE Conference
• /
• 2006.05a
• /
• pp.41-43
• /
• 2006

This paper deals with a comparison of individual and common grounding method for potential rise. When a test current flowed through grounding electrode, potential rise was measured and analyzed for grounding method using a electrolytic tank in real time. The grounding electrodes were designed and fabricated with ground rods on a scale of one-eightieth. Potential rises of individual grounding method were higher than those of common grounding method. The distributions of surface potential are dependent on the distance from grounding electrode.

• Bulletin of the Korean Space Science Society
• /
• 2004.10b
• /
• pp.231-234
• /
• 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.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.502-505
• /
• 1988

This paper is to demonstrate the effectiveness of one point grounding in support of ESS protection. One point grounding provides for the dispatching of excess energy for protection of switching equipment and personnel from lightning discharge hazards and for a natural sink for noise from atmospheric lightning and power transients. In most ESS installations there are a number of different items that must be maintained at a common ground potential for safety, fault protection or noise reduction. The items typically consist of power systems, heating and ventilating systems, distributing frames, repeating equipmets, switching equipments, etc. Grounding system of an ESS Office is most effective when all the ground points are connected to a single, common earth. The one point grounding prvides a common reference potential, keeping all the items of telecommunications facility free from the earth current and voltage hazards.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.740-741
• /
• 2007

This paper analyses the transient state of underground distribution system against single line to ground fault in underground transmission systems, when underground transmission systems and distribution systems are made of common grounding. Underground transmission systems and distribution systems are modeled by EMTP/ATPDraw. Simulation is carried out considering variation of parameters such as value of common grounding, balance load and unbalance load.