• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.319-322
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• 1999

In order to accurately measure the high voltage of 22.9[kV] power distribution lines, we investigated the temperature dependence of measuring voltage for single element and stack elements(22, 44, 66 layers, respectively). When one line voltage is 13, 20O[V], the error of measuring voltage with temperature(-25[$^{\circ}C$]~50[$^{\circ}C$]) was decreased with increasing of stack number and stack element with 66 layers was the least error of ${\pm}0.87%$.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.127-132
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• 2006

Pneumatic cylinders that are usually applied in the factory automation line have complicated failure cause because they are composed of various elements. In this study, we performed life test and performance test of double acting pneumatic cylinders according to the international standards and then analyzed the life and the main failure mode of the cylinders in the same load condition. On the basis of these processes, we can estimate shape parameter for the reliability estimation of pneumatic cylinders and their data analysis of life distribution.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.99-104
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• 2017

The three-phase four-wire power distribution system can be used to supply power to single-phase and three-phase loads at the same time. There are linear loads and nonlinear loads as single-phase loads connected to each phase. The nonlinear load generates a harmonic current during the power energy conversion process. In particular, the single-phase nonlinear load has a higher proportion of generation of the third harmonic current than the harmonics of the other orders. In a three-phase four-wire system, the third harmonic current flows through the neutral wire to the power supply side, affecting the power supply side and the line. Furthermore, the magnitude of the current flowing in the neutral line can be higher than the current flowing in the individual phase. If the neutral current is higher than the phase current, the breaker may be blocked. Therefore, it is necessary to reduce the amount of current flowing in the neutral line by harmonics. There is a method of zigzag connecting a single phase transformer by a method of reducing 3 harmonic current. In this study, the method of reducing the magnitude of the three harmonic currents flowing through the zigzag wire by comparing the polarity and the negative polarity characteristics of the single phase transformer was compared through measurement and simulation.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.166-172
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• 1997

The BEF on the radial distribution line refers to a class of ground faults in which the load-side power line only is grounded, with the distribution line broken into two parts, the source-side and the load-side. Because its mechanism is remarkably different from that of other earth faults, the fault current is very low, and then difficult to detect the BEF. Thus, it is necessary to analyze its properties and to find an appropriate method that can economically protect the BEF of nonautomation area in the substation. As a result of analyzing the BEF data obtained by the RTDS, EMTP simulation, and the field test data of ETSA, we believe that it is the dominant factor in distinguishing the BEF from normal conditions by a criterion value that is appropriately handled from the zero-sequence current. Thus, with this criterion value, a BEF detecting algorithm is constructed which measures the variations of the zero-sequence current and processes then properly so as to make the fault decision. To prove the accuracy of this algorithm, it is compared with the field test data of ETSA under various conditions. The results show that the proposed algorithm is accurate.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.1
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• pp.35-40
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• 2020

The purpose of this paper is to improve the grounding point measurement method for the maintenance of the earth resistance of the distribution line. This study defines the correlation among humidity of the soil, the earth resistivity and the grounding resistance. Based on the results of the study, the grounding resistance value measurement should be limited to the location where the earth resistivity change is large, and the measurement time and cost can be greatly reduced.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.302-304
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• 1999

Voltage sag and swell are the most severe factors affecting power quality in distribution systems. This paper discusses an approach to ensure a high quality power supply to critical loads appling voltage-sag compensator. The proposed system consists of a PWM voltage source inverter, connected in series with the line through a single-phase transformer. The operation Principle and Power circuit configuration of the proposed voltage sag compensator are introduced. And then the transfer function of compensator is derived from simplified single phase power circuit, and simulated so that the benefits of this proposed compensator is confirmed through the open loop response.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.737-743
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• 2013

The small-scaled onsite generators such as photovoltaic power, wind power, biomass and fuel cell belong to decarbonization techniques. In general, these generators tend to be connected to utility systems, and they are called distributed generations (DGs) compared with conventional centralized power plants. However, DGs may impact on stabilization of utility systems, which gets utility into trouble. In order to reduce utility's burdens (e.g., investment for facilities reinforcement) and accelerate DG introduction, the advanced operation algorithms under the existing utility systems are urgently needed. This paper presents the advanced voltage regulation method in power systems since the sending voltage of voltage regulators has been played a decisive role restricting maximum installable DG capacity (MaxC_DG). For the proposed voltage regulation method, the difference from existing voltage regulation method is explained and the detailed concept is introduced in this paper. MaxC_DG estimation through case studies based on Korean model network verifies the superiority of the proposed method.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.32-34
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• 1993

In Korea, the low voltage secondary distribution method comprises lots of the maintainable and conservative problems. So, this paper deals with the plans to solve and decide the unification of the low voltage secondary. That is ; for the unification plan of the low voltage secondary must be previously solved the breaking of netural line in $3{\phi}4W$, $1{\phi}3W$ and enacted the flicker criteria in distribution power system. To decide the low voltage secondary should take into considersion by economics, security and future. The flicker fluctuation in the low voltage secondary 7.4% in responsibility limited place and under 10% in Arc welding. To prevent the netural line in $3{\phi}4W$, $1{\phi}3W$ must be thoroughly constructructed, joined the two sleeves.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.43-48
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• 2016

Operational applications such as service restoration, voltage control and protection coordination are calculated based on the active and reactive power loading of the sections in the distribution networks. Loadings of the sections are estimated using the voltage and current measured from the automatic switches deployed along the primary feeders. But, due to the characteristics of the potential transformer attached to the switches, accuracy of the voltage magnitude is not acceptable to be used for section loading calculation. This paper proposes a new accurate section loading estimation method through voltage measurement error compensation by calculating voltage drop of the distribution line. In order to establish feasibility of the proposed method, various case studies based on Matlab simulation have been performed.