• Journal of the Institute of Convergence Signal Processing
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• v.16 no.3
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• pp.115-121
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• 2015

A device which could cut off the consumption of standby power by electric or electronic devices at homes and offices while waiting for a command to carry out the main functions from the inside or the outside was developed at a low price. Efforts to save standby power have been made on a global scale as well as by advanced countries. The consumption of standby power in South Korea is also increasing gradually due to increasing trend in the number of electronic and electric devices per household, becoming a major factor for waste of electric energy. The previous standby power cutoff devices themselves have high electric energy consumption and complicated structures, making the purpose less meaningful. Therefore, a low-priced standby power cutoff device is suggested in this study, which compensates such problems and cuts off the consumption of standby power completely. The circuit of the suggested standby power cutoff device was designed and implemented by applying it to an earth leakage breaker and an (electrical) outlet. Experimental results show its superiority.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.242-248
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• 2002

It is important to develop new effective technologies to increase the interruption capacity and to reduce the size of a UB(Gas Circuit Breakers). Major design parameters such as nozzle geometries and interrupting chamber dimensions affect the cooling of the arc and the breaking performance. But it is not easy to test real GCB model in practice as in theory. Therefore, a simulation tool based on a computational fluid dynamics(CFD) algorithm has been developed to facilitate an optimization of the interrupter. Special attention has been paid to the supersonic flow phenomena between contacts and the observation of hat-gas flow for estimating the breaking performance. However, there are many difficult problems in calculating the flow characteristics in a GCB such as shock wave and complex geometries, which may be either static or in relative motion. Although a number of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a GCB is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program using CFB-CAD integration technique based on Cartesian cut-cell method, which could reduce researcher's efforts to generate the mesh and achieve the accurate representation of the geometry designed by a CAD tools.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.480-480
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• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1073-1077
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• 2011

The breaking capacity of circuit breakers could be no more increased in the electric power system. This is because the fault current increases due to continuous increases in electric power demand and facilities. To solve the problem, it is necessary to come up with an alternative. The superconducting fault current limiter (SFCL) has received an attention among various alternatives. The SFCL effectively reduce a fault current in cooperation with a power circuit breaker. A various types of the SFCL are suggested and a study on them have been progressed. As a result of it, the SFCL can be applyed to the electric power system in the near future. But, a study on recovery behaviors of the SFCL is not enough for applying to the electric power system. If the superconducting elements do not completely recover to the superconducting state after fault operation, it might be a breakdown of the superconducting elements due to heavy power burden and it gives an bad influence on the working of other electric devices. Additionally, the distribution power system has reclosing operation such as open-0.3sec-closed/open-3min-closed/open procedure. So we need to study more about improvement of the recovery behaviors of the SFCL. In this paper, we analyzed the recovery behaviors of a flux-coupling type SFCL according to reclosing operation when a single line-to-ground fault occurred and we compared recovery behaviors of the SFCL with and without a neutral line between secondary reactors and superconducting elements. Also, the flux-coupling type SFCL has advantageous for increases of capacity by controlling the variation in turn ratios between two reactors. Consequently, when the number of turns of the secondary reactors increased, the power burden of the superconducting elements was bigger due to the increase of impedances of the secondary reactors. To distribute the power burden, two superconducting elements connected in series and the balanced quenching of the superconducting elements was induced by connecting a neutral line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1163-1171
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• 2017

The problem of fault current to exceed the rated capacity of a power circuit breaker can cause a serious accident to hurt the reliability of the power system. In order to solve this issue, current limiting reactors and circuit breakers with increased capacity are utilized but these solutions have some technical limitations. Back-to-back high voltage direct current(BTB HVDC) may be applied for reducing the fault current. When BTB HVDCs are installed for reduction in fault current, selecting the optimal location of the BTB HVDC without causing overload of line power becomes a key point. In this paper, we use genetic algorithm to find optimal location effectively in a short time. We propose a new methodology for determining the BTB HVDC optimal location to reduce fault current without causing overload of line power in metropolitan areas. Also, the procedure of performing the calculation of fault current and line power flow by PSS/E is carried out automatically using Python. It is shown that this optimization methodology can be applied effectively for determining the BTB HVDC optimal location to reduce fault current without causing overload of line power by a case study.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.107-112
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• 2017

In recent years, electric shock accidents due to electric leakage currents of household appliances such as computers, TVs, refrigerators, and LED lights are continuously occurring in homes and industrial buildings. And it is not easy to check the leakage current of each household appliances connected in parallel at the rear end of the module. In addition, the leakage current flowing through the path of the normal current other than the existing current leakage circuit breakers are installed in the distribution box, only the function to cut off the power when the leakage. Therefore, there are various disasters such as electric shock and fire caused by short circuit of household appliances, and the risk of such leakage current is seriously presented. In this paper, we propose a method to implement a leakage monitoring system that can be monitored at all times using Zigbee communication based on IEEE 80215.4, which has advantages in low power and low cost among short range wireless communication systems.

• Design & Manufacturing
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• v.10 no.1
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• pp.41-45
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• 2016

Electrical equipment in factories, buildings, etc. with the development of the industry has become a large capacity. By the development, electric load also become diversified and there is also highly functional requirements being electrical equipment. Particularly in the small and medium-sized circuit breakers, tend to preferentially consider the economy stands out and improvements in safety, ease of mounting and connection through the modularity of the basic dimensions compact and cost to block expansion of the scope of the development of capacity, etc. The product having a competitive has been strongly required. In order to implement the circuit breakers of breaking capacity and compact at the same time taking into account the economic development of this technology applied to the current-limiting mechanism is essential budget or the current limiting mechanism is currently available mechanisms applicable to small and medium-sized frame (frame) can not do it. In this paper, at the same time satisfying the economic efficiency, by minimizing the load force of the moving contactor (moving contactor) to be applied to small and medium frame other hand to secure the economical efficiency without using high speed contact parting acceleration of the moving contactor conventional current-limiting mechanism, and to develop a current-limiting mechanism that can be satisfied with the same or higher performance to meet the needs of the market.