• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.501-503
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• 2000

Since an arrester has been generally used at the distribution line and abroad for the protection of electrical equipments against overvoltage (or abnormal surge) taking place in or from an electrical system, a fault, especially, in the distribution line is very likely to result in the destruction of insulation of other protection devices to cause an overall paralysis of a power system, a chaos. Considering the importance of arresters, its earlier replacement than its proposed life cycle causes an economical loss, and a negligence not to replace or repair it in time gives rise to a crucial accidence. The purpose of this paper is to invent an electric leakage current detector and to solve such problems by the continuous and regular inspection of an arrester.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.103-105
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• 2008

In, this paper, we consider the relation between on-line monitoring and diagnostics on the one hand and high-voltage (HV) withstand and partial discharge (PO) on-site testing on the other. HV testing supplies the basic data (fingerprints) for diagnostics. In case of warnings by on-line diagnostic systems, off-line withstand and PO testing delivers the best possible information about defects and enables the classification of the risk. Because alternating voltage (AC) is the most important test voltage, the AC generation on site is considered. Frequency tuned resonant (ACRF) test systems are best adapted to on-site conditions. They can be simply combined with PO measuring equipment. The available ACRF test systems and their application to electric power equipment -from cable systems to power transformers - is described.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.875-877
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• 1997

Due to the development of electric energy conversion technology and need for energy saving most of the electric machinery and equipments are using power semiconductor switching elements, On the contrary semiconductor switching device is more sensitive to the voltage instability and voltage distortion. In order to manage the voltage distortion following foundation should be settled down in advance. First, reasonable and objective technical guidelines should be established. Second, monitoring network for power quality should be operated. In this paper measurement results of the harmonic distortion of the special loads are given and method for harmonic pollution management is discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.23-28
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• 2000

Insulator systems using resin casting apparatus are useful to realize the high capacity, small size, and combined electric power equipments, and are expected to bring various advantages. In Korea, epoxy resin molded apparatus have been restricted to indoor uses till now. On the other hand, in Europe, molded insulators and transformers and so forth have been practically used since the former half of 1960's. Recently, investigation on epoxy resin materials and molded apparatus for outdoor use have ben intensively carried out. Probably, this is because electric power outdoor apparatus such as distribution transformer can be given multi-functions by using outdoor epoxy resin compound This study describes the trend on the development of epoxy mold transformers, and important technologies applied for outdoor use.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.37-40
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• 2002

Ground connection began by experimenting lightning with the use of a kite and it means electric appliances, communication equipments, measuring instruments and so on connecting the Earth in order to flow away overcharged electricity. There are two kinds of earth connection: Power Ground and Signal Ground. Power Ground is for preventing an electric shock and in general there's no current in the connector. However in an accident, there's a quick flow of electricity out to the Earth. Signal Ground is not only for the safety of appliances but also for the safety of equipment operation. This paper is about connection for noise and interference reduce in order to prevent wrong operation and distortion of signal in the electrical appliances which can take place in cable TV.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.4
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• pp.37-46
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• 1998

This paper analyzes the present state of customers' effect in distribution system by momentary voltage variation. Customers are becoming increasingly concerned about the quality of electric power. Most of all, the voltage magnitude quality is very important because it can have a direct effect on customers. Especially, according to the development of automatic process, momentary voltage variations result in the shutdown of sensitive loads such as electronic equipment, computer and magnetic contactor, and so on. To analyze the shutdown rate of customers' equipments by the momentary voltage variation, we present the CVEMA curve and he cumulative CVEA curve of each load type through the experiment for the customers' sensitive equipments. Also, we have surveyed customers' opinion by the questionnaire as "Survey of Power Quality" an then the results are reported.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1552-1553
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• 2011

The HVDC transformer which is one of the main equipments for HVDC(High Voltage Direct Current) electric power transmission systems is exposed to not only AC voltage but also the inflowing DC voltage which comes from the DC-AC converter systems. Therefore, the HVDC transformer insulation system is required to withstand the electric field stress under AC, DC and DC polarity reversal conditions. However the electric field distributions under those conditions are different because the AC electric field and DC electric field are governed by permittivity and conductivity, respectively. In this study, the changes of electric potential and electric field of conventional AC transformer insulation system under DC polarity reversal test condition were analyzed by FEM(Finite Element Method). The DC electric field stress was concentrated in the solid insulators while the AC electric field stress was concentrated in the mineral oil. In addition, the electric stress under that condition which is affected by the surface charge accumulation at the interfaces between insulators was evaluated. The stress in some parts could be higher than that of AC and DC condition, during polarity reversal test. The result of this study would be helpful for the HVDC transformer insulation system design.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.461-468
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• 2014

An efficiency test for generators is generally required in case of construction of a new power plant or replacement of an existing generator. Generally, the efficiency of generator is measured by the input-output ratio under any given condition. Therefore, the best way is to directly measure the value of input and output power of a generator and calculate the efficiency values. However, it is difficult to measure a generator's input values accurately, especially for large systems. So, we are usually measuring the losses of the generator. But for measuring these values, there are several constraints for test such as preparing additional power generator and releasing the protection relay for manual operation of auxiliary equipments. Therefore, this study suggests that a novel generator efficient test method using the shaft-torque method which can be carried out while the generator is normally operating. The reliability of the result value was verified by comparing with the efficiency test results of the conventional retardation method on IEEE Std 115-1995.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.287-294
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• 2006

Recently, switchboards for MV/LV distribution customers have been united and digitalized rapidly. This paper proposes the effective information visualization method for the data measured from cubicle switchboards for MV/LV distribution customers. We developed the algorithm that analyzes abundant data measured by switchboards and displays them to overall users, such as fire information index, power condition index, switchboard safety index, and power diminution index. Using a touch screen made users to operate it easily. User interface was also improved by taking graphic visualization. We guess the information visualization method suggested in this paper shows the new direction that heavy electrical equipments including switchboards are going to develop in the future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.245-249
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• 2014

Wireless power transfer (WPT) system is very attractive because it removes power cables from home appliances, office equipments and battery chargers for electric vehicles. In this paper, non-radiative WPT systems studied recently are claimed to be technologically or theoretically identical in operation irrespective of the number of coils. Especially, 2-coil and 3-coil systems are compared in detail. It is also shown that multiplicity of coils does not increase power transfer capability.