• 한국안전학회지
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• 제30권4호
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• pp.39-45
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• 2015

This paper deals with development of integrity evaluation instrument for the power line surge protective device. A reliable power supply is an essential element in the developed information and communication society by highly advances in IT technology. However, the lightning incidence also increased with the recent extreme weather events. In Korea, in order to protect the electrical system from lightning surge, SPD(Surge Protective Device) has been used for these past 30 years. However, the method of diagnosing the safety of the SPD in the industry is insufficient. In this paper, SPD integrity evaluation system was composed of a variable DC power source unit, voltage-current sensor and the embedded controller. In order to measure V-I characteristics of MOV, 3 type samples were degraded by impulse current generator. After impulse tests, the varistor voltage of all samples and nonlinearity coefficient were decreased. It confirmed the utility of the developed equipment by this experimental test and the reliability of SPD is expected for surge accident prevention when applied to industrial plant.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.52-59
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• 2014

The aims of this paper are to characterize the transient overvoltages(TOVs) and to evaluate the risk occurring at 22.9kV consumer's substation. The measurements of lightning- and switching-caused TOVs were made during Mar. 2013 and Feb. 2014. As a consequence, 47 events of TOVs were recorded and 4 of them were higher than the input voltage envelope(IVE) of the information technology industry council(ITI) curve. The measured TOVs are characterized by longer front times and longer durations compared to the $1.2/50{\mu}s$ standard impulse voltage waveform, and some of them represent bipolar waves with lower oscillation frequencies. It suggests that the test of non-standard impulse voltage waveforms is needed for effective risk assessments of power apparatus. Lightning- and switching-caused TOVs exceeding IVE of ITI curve are induced at the secondary of 22.9kV potential transformer(PT). We may, therefore, conclude that the surge protection devices should be applied at the secondary of PT and the surge absorbers should be installed at the primary of VCB or PT. The results presented in this paper could be useful to design the reasonable insulation coordination for 22.9kV consumer's substation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1675-1677
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• 1998

It is currently increasing to use surge protection devices in the protection of various electronic circuits from the transient overvoltages such as lightning strikes and switching surges. For this reason, the simulation methods, which can easily predict the protection performance of the devices, are strongly required in order to design the adequate surge protection circuits in lightning surge cut-off performance and economic aspects. This paper deals with ZnO varistor modeling method for designing a surge protection circuit and suggests the Pspice simulation model which takes the characteristic of varying clamping voltage into consideration during the time-to-crest, in range of $8{\sim}30{\mu}s$, of surge current applied to a ZnO varistor. The ZnO varistor Pspice simulation data introduced in this paper has produced almost same values as the measured results experimentally.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권4호
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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.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.502-509
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• 2002

In the analysis of lightning surges, transmission towers are usually simulated by ATPDraw. The modeling of transmission towers is an essential part of the traveling wave analysis of lightning surges in transmission lines. The tower model is applied to the 154kV transmission tower of which surge performance characteristics are measured Tower surge response is computed using nonuniform, single-phase line models for both transmission tower and ground wire. The overvoltage will effect to the underground transmission line. The underground cable is combined by duct and trefoil type, and the each arrester is placed on the leading-in tube and outgoing tube. This paper analyzed the effect of lightning overvoltage on the underground cable system.

• 전기학회논문지
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• 제62권9호
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• pp.1302-1307
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• 2013

MOV(Metal Oxide Varistor) is the most important part of SPD(Surge Protective Device) which can protect electric facilities from an impulse current such as a lightning. So far, the fault of MOVs have decided only by surge count without considering magnitude of surge current and an amount of input energy. This paper proposed the fault prediction algorithm for the MOV using look up table made by surge count and input current data which have non-linear characteristics for input current and are estimated by high voltage experimental results. Proposed algorithm was proved by experiment on verification at a high voltage laboratory.

• KIEE International Transactions on Power Engineering
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• 제5A권2호
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• pp.171-176
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• 2005

The effects of surge arresters for the protection of transmission systems against direct lightning strokes have already been reviewed by many researchers. However, their studies have not encompassed underground cable systems. Therefore, in this paper we investigate the 22.9kV combined distribution systems that have arresters and ground wires. In addition, we analyze the overvoltages on underground distribution cable sections when direct lightning strokes contact the overhead ground wire using EMTP. Finally, we discuss the effect of lightning strokes according to the change of cable length and installation of arresters. This study provides insulation coordination methods for reasonable system design in 22.9kV underground distribution cable systems.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.90-99
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• 2004

고도 정보화 사회의 발달과 함께 정보통신 설비는 빠른 전송속도를 필요로 하며, 지능형 산업설비와 행정, 금융, 교통시스템과 같은 사회시스템은 집적회로와 초소형 반도체로 구성되므로 원격감시, 조작에 의해 점차적으로 자동화 되어가고 있다. 이와 같은 현대의 초소형 전자회로는 뇌 서지에 의해 흔히 손상을 입을 수 있으며, 뇌 과전압으로부터 전자회로의 보호에 관심이 집중되고 있다. 본 논문은 일반주택에서 뇌 서지로부터 초소형 컴퓨터와 같은 전자기기의 효과적인 보호방법을 제안하기 위하여 전원계통의 접지방식에 따른 서지보호기의 보호효과를 실험적으로 분석하였다. 또한 서지보호기의 효과적인 설치방법을 조사하고 제안하였다. 기존의 설비에 추가적으로 서지보호기를 설치하는 것은 서지보호기까지의 긴 접속선으로 인한 인덕턴스 때문에 높은 잔류전압이 나타난다. 서지보호기의 설치에 있어 두 접속선을 꼬는 방법이 급격하게 상승하는 과도과전압에 매우 효과적이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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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.

• 전기학회논문지
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• 제62권1호
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• pp.1-7
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• 2013

This paper analyzes the flashover rate by lightning in Korea distribution system. Because of random characteristics of lightning, the Monte Carlo method is applied to estimate the lightning performance. The magnitude of lightning stroke is based on the curve measured in field. The classification of direct and indirect lightning depends on the striking distance. The striking distance and flashover rate are calculated by using the method based on Central Research Institute of Electric Power Industry(CRIEPI). The distribution system and lightning is modeled by using EMTP and MATLAB, and the accuracy of modeling is discussed. The simulations for the various spacing between two adjacent surge arresters and the various grounding resistance of GW according to the existence of GW are performed and the simulation results are analyzed.