• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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• pp.149-156
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• 2004

This paper deals with the effective protection method for the household electric appliances against lightning surges invading from the Power lines. Direct or induced lightning is the main cause of the breakdown of household electric appliance. The most effective protection method is to install SPDs(surge protective devices) at household electric appliances. If SPDs were not installed at most household electric appliances, it is necessary to install SPDs on the mains. Therefore the propagation aspect and protection methods of lighting surges coming into household electric appliances through the mains was experimentally investigated. The in actual-sized test circuits results of protection method for 8 household electric appliances including computer monitors and TV set could be summarized as follows: The breakdown characteristics of household electric appliances from lightning surges were significantly changed with the their input impedance. Namely, the types of input impedance are classified into infinite, resistive or inductive impedances. Especially, the monitor for computer with inductive input impedance from lightning surges was relatively weak against lightning surges. It was confirmed that the self inductance of branch circuits on the mains have protection effect for household electric appliances against lightning surges invading from the power lines. Also the varistors installed at cabinet panel or circuit-breaker were more effective than multi-tap outlet with varistors. When installed varistors in cabinet panel and multi-tap outlet together, the surge protection effect is much more excellent in technical and economical aspects.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.4
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• pp.117-122
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• 2003

The AC power lines and signal lines of info-communication networks are routed on overhead poles and are highly exposed to lightning strikes. Due to the potential difference between grounding points of AC power lines and signal lines, the electronic equipments connected to the signal lines can easily be damaged by lightning surges. In this work, in order to develop reliable methods of protecting information and communication facilities from lightning surges, the reliability and performance of SPDs (surge protective devices) were experimentally investigated in an actual-sized test circuit. The behaviors of SPDs against lightning surges from AC power lines and signal lines and the coordinated effects of SPD installation methods were evaluated. As a consequence, it was confirmed that the bypass arrester methods and common grounding system are both highly effective.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.67-74
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• 2010

Most of domestic low-voltage consumers are supplied from the TN-C system of KEPCO, but their load installations have established according to the national statutory standard for electrical installations based on the TT system. In this work, to propose the proper system earthing arrangements of ensuring the protection of information-technology equipment against lightning surges, the protection performance of TT and TN systems against lightning surges was investigated. As a result, when lightning surge was injected to the neutral line of distribution system, the potential difference between the equipment earth terminal and neutral point of low-voltage mains in a TT system was significantly raised. The TT system is not advised due to the risk of damage to the sensitive computer equipment. Main equipotential bonding is an important requirement for protection of low-voltage installations against lightning surges. The TN system provides the best means to reduce the incoming lightning surges through the neutral line of low-voltage service systems. In addition, It is highly recommended to install the additional earthing at the service position of low-voltage consumers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.90-96
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• 2002

The AC power lines and signal lines of info-communication networks are muted on overhead poles and are exposed to lightning strikes. Due to the potential difference between groundings of the AC power lines and telecommunication lines, the electronic equipments connected to the telecommunication lines can easily be damaged by lightning surges. In this work, in order to develop the reliable ways to protect information and communication facilities from lightning surges, the reliability and performance of surge protective devices were experimentally investigated in actual-sized test circuit. The operation behaviors of surge protective devices against lightning surges from the AC power lines and telecommunication lines and the coordination effects of SPD installation method were evaluated. As a consequence, it was confirmed that the bypass arrester and common grounding system is very effective.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.100-105
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• 2007

Signalling equipments at railroad sites are widely exposed to high voltage lightning surges. This paper presents a lightning protection system for the signalling equipments at subway car depots. The main features of the system are as follows : (1)the common grounding system between power system grounds and the signaling system grounds, (2)physical and chemical methods to reduce grounding resistivity, (3)rearrangement of lightning rods based on the rolling bal1 theory, (4)equi-potential bonding networks to minimize the potential differences between the equipments grounds. The system has been constructed at six subway car depots in Seoul metropolitan area and it is measured that the grounding resistivity are reduced to 0.266 ohms and the potential differences between devices are reduced to a negligible quantity. After the construction of the systems, it has not been reported the break-down of the signalling equipments caused by lighting surges.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.468-471
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• 2002

A strong need to improve the quality of electric power is increased because of increasing use of the sensitive and small-sized electronic devices. The surges on the low-voltage ac power lines are induced by nearby lightning return strokes, and the facilities for HA, OA, FA, ME as well as computer are easily damaged by high-voltage transients. The behaviors of lightning surge characteristics transferred from the primary winding to the secondary winding in distribution transformers using a Marx generator were experimentally investigated. The transfer characteristics of lightning surge associated with a custom service ground of secondary side were also examined.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1718-1720
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• 1997

This paper deals with n rise in electric potential of telecommunication line for electric power system by lightning surges. When $1.2/50{\mu}s$ and $8/20{\mu}s$ impulse voltage and current were applied on telecommunication cable, the voltage waveforms at the end terminal and equipment were measured. The telecommunication lines, which consist of 60 conductors and 3.5km in length, have some surge protectors such as preposition lightning arrester and TVSS. In each case, the rise in electric potential was measured for differential mode and common mode, respectively. Also, the rise in ground potential and the induced voltages were measured and analyzed. As a result, a significant rise in ground potential was observed for lightning surge. It can cause failure or malfunction of telecommunication systems.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.73-76
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• 2001

This paper dives the current status of lightning damages in apartments obtained by questionnaire and analysis the cause of ligntning damages. As a result, the apartments experienced lightning damages are assumed about 5[%] lot total apartments and the lightning surges invaded on power line are identified as the main cause of lightning damages in apartments.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1712-1714
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• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.60-67
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• 2006

This paper presents the protection effect of surge protective devices(SPDs) according to the conditions of installations. To propose the effective protection measures of information and communication equipments against lightning surges, actual-sized experiments in relation to the protection effects on the positions of installations of SPDs, the length of branch circuit, the wiring methods, and the materials of conduit, were conducted. The effective method of protecting information and communication equipments from lightning surges is to install SPDs in the vicinity of input terminals of each electronic equipments to be protected. The wiring method of connecting an SPD minimizing the length of leads is desirable when point-to-point wiring is to be used.