• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.27-33
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• 2017

This study is intended to identify issues on the basis of investigating the actual state of laboratory environment and outlet circuit, and derive end states by expressing sequences from the initiating event of disaster to accident in leakage current, poor contact and overload through ETA(event tree analysis). To this end, this study investigated the actual state of electric equipment of laboratory at universities in all parts of country. And it is shown that most of them are failure in electric work and user negligence in the investigation of actual state. It is found that there is earth fault and defect in wire diameter in the failure of electric work and the problem of partial disconnection due to wire bundling and poor contact in user negligence. Outlet-related component, failure rate and initiating events are composed of a total of 41 initiating events, i.e., 30 internal initiating events and 11 external initiating events. And end states are composed of a total of 15 parts, i.e., 3 electric power parts and 12 safety parts. Earthing class 3 is the most important safety device against leakage current (initiating event). And in case of poor contact, it is necessary for manager to check thoroughly because there is no safety device. In case of overload/overcurrent, when high-capacity equipment is connected, a molded case circuit breaker, safety device, worked. However, in most cases, it is verified that this doesn't work. This study can be utilized as electric equipment safety guide for laboratory safety manager and managers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.123-128
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• 2021

As the spread of DC power distribution systems increases, the occurrence of failures and fire accidents are also increasing. In particular, the ESS fire accident, which is a component of the smart grid, and the fire accident of the solar power system, which is a direct current system, are caused by problems in the electrical connection between system components as the supply of new and renewable energy rapidly increases and old facilities increase. An arc that can cause a direct fire by releasing the induced light and heat has been pointed out as one of the causes of fire. Therefore, the problem of such an arc defect is that it is impossible to block an arc accident in advance with the existing overcurrent circuit breaker and earth leakage circuit breaker. In this paper, we intend to develop a test equipment that satisfies international standardization and to develop a DC arc generator to protect against failure and fire caused by arcing.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.495-496
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• 2011

기존에 사용되고 있는 초고압 가스차단기(GCB : gas circuit breaker)는 대부분 퍼퍼형(puffer type) 소호방식의 가스 차단기를 사용하였다. 퍼퍼형 소호방식은 차단동작에 있어서 대단히 큰 조작력이 요구되고 소호부 size가 큰 단점을 가지고 있다. 이러한 문제를 해결하기 위해 아크 자체의 에너지를 아크 소호에 필요한 압력상승을 일으키는 데 이용하는 자력소호방식(self-extingishing type)에 작은 체적의 퍼퍼 실린더를 병용하는 복합소호방식(hybrid extingishing type) 차단부가 개발되어 사용이 확대되고 있다. 본 논문에서는 차단기의 소호방식별 특성을 비교 분석하고 최근 사용이 확대되고 있는 복합소호방식 차단기의 고장사례 분석을 통해 개선대책을 제시하였다.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2080-2082
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• 1999

This paper describes the analysis results for the protection of lightning surge at 154 kV substation. We found that the surge arrester is needed at the inlet structure. The maximum overvoltage is 975 kV at the circuit breaker without the surge arrester at the inlet structure. This value can be lower than 600 kV by installing the surge arrestor at the inlet structure. In addition to the incoming surge from transmission line, the shield wire should be considered to prevent the shielding failure by the direct lightning stroke.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1888-1890
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• 2000

This paper describes the analysis results for the protection of lightning surge at 154 kV substation. We found that the surge arrester is needed at the inlet structure. The maximum overvoltage is about 1,500 kV at the circuit breaker without the surge arrester at the inlet structure. This value can be lower than 600 kV by installing the surge arrestor at the inlet structure. In addition to the incoming surge from transmission line, the shield wire should be considered to prevent the shielding failure by the direct lightning stroke.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.75-81
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• 2014

It has been widely accepted that open phase may separate one of the power lines from power supply which is mainly caused by fuse melting, malfunction for source circuit breaker, contact failure, and disconnection under normal operating conditions, and is considered a kind of failure mode during disconnection of neutral wires as well. When open phase occurs, unequal voltage between phase might happen in the unbalanced load connected each phase, and further, depending on conditions of load, malfunction by providing low voltage. Moreover, load could be burned or overheated with overvoltage, which, in turn, can be a contributor to starting fires. Accordingly, in order to clearly overcome these problems, the current study aims to introduce the theory of uninterruptible power open phase compensation device, meaning that unbalanced power automatically restores balanced power and provides continuously the power supply without blackout, and verify it through simulation and experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.262-267
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• 2011

In the power system, the transformer's neutral earth reactor line 1 grounding failure may occur. By limiting the magnitude of the failure grounding current flow, it will aid to reduce the failure of the transformer. Consequently, this also may avoid the failure of the disconnection of the industrial insulator line that cause by melting. Besides, utilizing the decreasing circuit breaker or others related equipment can use to avoid the possibility of explosion of the transformer. If the failure happen during the operation of the power system, a huge interference will definitely may occur. Therefore, by installing the DONGBUSAN S/S #3M.Tr neutral earth reactor among TOP and BOTTOM BRACE part in the power system, the causes of the rising temperature and reason of the over-current flow that cause by over-current can be analyze.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.480-488
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• 2006

Up to recently the harmonic generation has deteriorated the quality of electricity and affected the performance on the electrical installation including OA, FA, IT devices and so on. Some studies of harmonic affects in diagnosis and the cause of accident has not done by the experimental data of harmonic source but merely by presumption according to qualitative analysis. So, in order to research the harmonic affect on the electrical installation according to quantitative analysis and gather reliable data over and over again, it is necessary to develop an AC power source which is capable of generating some harmonics. In this paper, we described about realization of AC power source which can produce and compose harmonics for the analysis of accident due to harmonics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.87-93
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• 2005

Recently, nuisance tripping or malfunction of MCCB(Melded Case Circuit Breaker) and ELB(Electrical Leakage Breaker) is being increased according as load circuits and equipments of electrical customers are various and complicated, but investigation of actual conditions on malfunction of MCCB and ELB was not implemented This paper investigated causes and influences of malfunction of MCCB and ELB by making up a question to electrical safety managers of two hundred and eighteen private electrical facilities. The results show that users above $70[\%]$ experienced malfunction of MCCB and ELB, and causes of malfunction are in order aging(above $25(\%)$), nuisance tripping $(above\;22(\%))$, goods badness$(above\;20(\%))$, abnormal power like as harmonics$(above\;20(\%))$ and others $(about\;9(\%))$. Also, second damages due to failure of MCCB and ELB are in order goods production, equipment trouble, information loss, business and operation interrupt, and others. The results of this study can be used in making decisions regarding causes of MCCB and ELB trip.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.21-25
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• 2013

The purpose of this study is to provide basic data for the safety assessment of a water purifier when water leaks due to inappropriate maintenance and the examination of the cause of accidents related to the leak. Due to its inspection and management by non-specialists, if a leak occurs in a water purifier with the water level controller being inclined, it may result in the failure of the compressor, power supply line, PCB, etc. The analysis of the thermal diffusion pattern of water purifier compressors using a thermal image camera shows that its maximum temperature was approximately $80^{\circ}C$. In addition, its operating current was a maximum of 13 A and the system's operating current was approximately 1.7 A after the compressor was charged. It was found that the housing type power cable cover of the compressor had the effect of preventing electric shock but has poor flame resistance. Furthermore, the performance of the overload protector, PTC relays, etc., was excellent but they have potential for problems as metallic terminals were exposed, resulting in the potential of a safety related accident. The terminals and their surface damaged by the tracking showed a trace of carbonization and the resistance between terminals was measured to be approximately $8{\Omega}$. In addition, while the tracking was proceeding, the fuse and circuit breaker installed for system protection did not operate.