• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.191-192
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• 2008

We give new definition of the effective-leakage and the signal to effective-leakage plus noise ratio (SELNR) to consider receiver combining motivated by the leakage. We propose a method to find jointly beamforming vector and combining vector for the two linear receivers (maximal ratio combining (MRC) receiver and minimum mean square error (MMSE) receiver) based on the SELNR.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1883-1890
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• 2017

Transformers are one of the most precious elements of the electric power system. Stability and reliability of the electric power network mainly depend on the working of the transformer. Leakage reactance of the transformer is one of the important factors and accurate calculation of the leakage reactance is necessary for the transformer designers and electric distributors. Leakage reactance of the transformer depends on the geometry of the transformer. There are many different methods for the calculations of the leakage reactance however mostly are usable when the axial heights of the high voltage and low voltage windings are equal. When the axial heights of high voltage and low voltage windings are asymmetric most of the analytical methods are not reliable. In this study, a new analytical method is introduced for the calculation of the leakage reactance. Fourteen different transformers are investigated in this study and four of them are presented in this paper. The results of the new analytical method are compared with the experimental results. Other analytical and numerical methods are also compared with this new method. Results show that this method is more reliable and accurate as compared to the other analytical methods. The maximum relative error between short-circuit test and proposed method for these fourteen transformers was less than 2.8%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.207-210
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• 1998

Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition. The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.758-762
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• 1998

Electrical conduction property of insulator surface is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the materials to be used for outdoor insulator such as porcelain, EPDM, silicone rubber was discussed by measuring properties of average leakage current and scintillation discharge pulses under salt fog conditions. The fog was applied by nozzle in chamber and fogging fluids were deionized distilled water, 0.5wt% NaCI solution and 2wt% NaCl solution. The average leakage current showed linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage were much different to those in case of dry and clean condition with 2wt% salt fog. In case of slat fog pollution condition, the leakage current was increased above critical voltage. the scintillation discharges were also activated at the level. The leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.131-137
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• 2005

This paper describes a new approach to the algorithm and fundamental characteristics of the device for monitoring the leakage currents flowing through zinc oxide (ZnO) surge arresters. In order to obtain a technique for a new on-line monitoring device that can be used in the deterioration diagnosis of ZnO surge arresters, the new algorithm and on-line leakage current detection device for extracting the resistive and capacitive currents using the phase shift addition method were proposed. The computer-based on-line monitoring device can sense accurately the power frequency leakage currents flowing through ZnO surge arresters. The on-line leakage current monitoring device of ZnO surge arresters proposed in this work has the high sensitivity compared to the third harmonic leakage current detection devices. As a consequence, it was found that the proposed leakage current monitoring device would be useful for forecasting the defects and degradation of ZnO surge arresters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.79-86
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• 2013

In order to analyze the electrical performance of ZnO surge arresters stressed by the combined DC and AC voltages that are generated in DC/AC converter systems, the leakage current properties of ZnO surge arrester blocks deteriorated by impulse currents were investigated. The test specimens were deteriorated by the 8/$20{\mu}s$ impulse current of 2.5kA and the leakage currents flowing into the deteriorated zinc oxide(ZnO) arrester blocks subjected to the combined DC and power frequency AC voltages are measured. As a result, the leakage currents flowing through deteriorated ZnO surge arrester blocks were higher than those flowing through the fine ZnO surge arrester blocks and the larger the injection number of 8/$20{\mu}s$ impulse current of 2.5kA is, the greater the leakage current is. The leakage current-voltage curves(I-V curves) of the fine and deteriorated ZnO surge arrester blocks stressed by the combined DC and AC voltages show significant difference in the low conduction region. Also the cross-over phenomenon is observed at the voltage close to the knee of conduction on plots of I-V curves.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.655-658
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• 2005

Due to reduced device sizes and threshold voltages, leakage current becomes an important issue in CMOS design. In a CMOS combinational logic circuit, the leakage current in the standby state depends on the state of the inputs and thus can be minimized by applying an optimal input when the circuit is idling. In this paper, we present a New Input Vector Control algorithm, called Leakage Minimization by Input vector Control (LMIC) for minimal leakage power. This algorithm finds the minimal leakage vector and reduces leakage current up to 22.% on the average, for TSMC 0.18um process parameters. Minimal leakage vectors are very useful in reducing leakage currents in standby mode of operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.503-506
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• 2001

This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL3, it confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances L$\sub$r1/ and L$\sub$R2/ of the primary and secondary windings were calculated, their values are 4.23 mH and 0.49 mH, respectively. They are also similar to the measured values of the leakage inductances for the experimental verification, 4.06 mH and 0.47 mH.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.9
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• pp.464-469
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• 2004

The leakage current of transmission insulators contaminated with salt, clay, and kaolin was examined in the Gochang's Long Periods Testing Center. The Insulators were artificially contaminated and estimated with the method of equivalent salt deposit density(ESDD). The artificially contaminated insulators were installed with the same condition as in the real transmission power line and applied with 154 (kV). The leakage current of the artificially contaminated insulators was measured with environment conditions, such as temperature and humidity by the a automatic leakage current detecting system. The leakage current of heavily contaminated insulator was abruptly increased above 72［%］ of humidity, even though the leakage current was similar between the contaminated and non-contaminated insulators below 72［%］ of humidity. Also, it was found that the humidity was much more important than the temperature in the leakage current of transmission insulators. The leakage current of contaminated insulator was decreased when it was plenty of rainfall, resulting from natural washing.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.11
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• pp.572-576
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• 2004

Various devices for diagnosing arrester soundness are suggested, and most of them simply measure magnitude of leakage current. However, such kind of devices do not provide detailed information needed for the diagnosis. In this study, we designed and fabricated a new arrester analyzer by means of measuring the magnitude, the phase vs. wave height and the harmonics of total leakage currents. The analyzer is composed of a current detector, an optical linker, and a main device operated by a microprocessor. The main device is connected with leakage current detector optically not to be influenced by electromagnetic interference. The analyzer developed measures only total leakage currents, but analyzes most parameters needed for the arrester diagnostics.