• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.174-177
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• 2003

Kinds of most frequent faults happened on overhead distribution system are the single line-to-ground fault, the line-to-line fault and the two line-to-ground fault. Occasionally, the three line-to-ground fault and the disconnection of a wire are happened in severe conditions. In this study, the single line-to-ground fault, the line-to-line fault, two line-to-ground fault on three-phase four-wire overhead distribution system were experimentally simulated and characteristics of total leakage current of distribution arrester caused by these faults were investigated. Also, the changing aspect of total leakage current of distribution arrester caused by voltage variation was investigated. In a consequence, abnormal voltages caused by voltage variation, the line-to-line fault, the two line-to-ground fault have a little effect on total leakage current of ZnO arrester. But abnormal voltages caused by the single line-to-ground fault have an important effect on total leakage current of ZnO arrester.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.147-147
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• 2009

Every year respect a countermeasure establishment the electric leakage detection system and electric leakage investigation work are becoming enforcement line plentifully in about the electric leakage accident which is increasing, measuring in compliance with a most ground connection voltage and an image electric current mainly is become accomplished, inputs a pulsation group signal in the line and detects a signal change between the line a method which there is. In order to investigate the quality in compliance with an electric leakage electric current from the electric leakage area after conferring the electric leakage environment in compliance with a flooding when the electric leakage electric current exists in the surface, it investigated the electric leakage electric current quality from the electric current distribution and flooded districts from the present paper.

• 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.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.404-411
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• 2003

Three-dimensional vortical flow and separated flow topology near the casing wall in an axial flow fan having two different tip clearances have been investigated by a Reynolds-averaged Wavier-Stokes (RANS) flow simulation. The simulation shows that the tip leakage vortex formed close to the leading edge of the blade tip on suction side grows in the streamwise direction. On the casing wall, a separation line is formed upstream of the leakage vortex center due to the interference between the leakage vortex and main flow. The reverse flow is observed between the separation line and the attachment line generated downstream of the trailing edge, and increased with enlarging tip clearance. The patterns of a leakage velocity vector including a leakage flow rate are also analyzed according to two tip clearances. It is noted that the understanding of the distribution of a limiting streamline on the casing wall is very important to grasp the characteristics of the vortical flow in the axial flow fan.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.885-891
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• 2011

In this paper, we studied dc leakage current properties analysis of LED lamps of road and landscape lighting when leakage current appeared in dc power line. Generally, converter of LED lighting is divides to insulated type and non-insulated type according to components. When electric leakage happened in AC power line, earth leakage breaker(ELB) senses leakage current and interrupts electric circuit. In dc power source, We need experimental verification about dc electric leakage for electricity safety. In normal wiring conditions and in the water, in case of using insulated type of converter, dc leakage current did not occur. However, in case of using non-insulated type of converter, dc leakage current occurred and passed through into the ground. We found that there is a hazard of electric shock by dc leakage current. We expect that the results of these studies would be helpful for electrical safety of LED lamps for road and landscape lighting.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1461-1470
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• 2012

This paper reports the contamination performance of transmission line porcelain insulators tested under five different contaminant conditions - clean and ESDD (equivalent salt deposit density) level (A, B, C, and D) through measurement of their leakage current under drop of potential method. To estimate the contamination for transmission line porcelain insulators, leakage current waveform and its maximum value were measured under step-up power test. In the clean insulators test, % distortion factors decreased with increasing step-up power, and as the ESDD level increased, some characteristics such as frequency analysis, harmonics and % distortion facotor could be used for contamination diagnosis of the transmission line porcelain insulators.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.828-833
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• 2014

Grid connected transformerless solar power generation system is frequently used with the benefits of cost and efficiency. However, significant DC leakage current can flow from the DC line into the ground with dielectric breakdown in the transformerless solar power generation system. The leakage current occurred in the DC line causes accidents such as fire and electric shock on human. To resolve this problem, high sensitivity DC leakage current sensor is needed. But recently the studies on safety of DC line are not performed. In this paper, a high sensitivity DC leakage current sensor that can detect DC leakage current in solar power generation system, is proposed. Based on the studies, DC leakage current sensor is fabricated and characteristic tests are carried out. Finally, the accuracy of sensor performance is verified by leakage current experiments in solar power generation system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.817-821
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• 2017

As a ZnO varistor is subjected to electrical and environmental stresses, it degrades gradually, which may result in power interruption by short circuit. This study investigates changes in the electrical characteristics of ZnO varistors due to deterioration owing to energy absorption, and determines the optimal parameters for on-line diagnosis of the varistor. Two types of varistors were used for an accelerated aging experiment involving the application of the $8/20{\mu}s$ standard lightning impulse current. The electrical characteristics in terms of the reference voltage, total leakage current, resistive leakage current, and third-harmonic component of the total leakage current were measured, and their change rates were analyzed. The results revealed that the total leakage current increased slightly with an increase in the varistor absorbed energy, while the resistive leakage current and the third-harmonic component increased apparently. Therefore, the third-harmonic component of the total leakage current was proposed as the optimal parameter for on-line monitoring of ZnO varistor conditions.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.36-44
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• 2004

Three-dimensional vortical flow and separated flow topology near the casing wall in an axial flow fan having two different tip clearances have been investigated by a Reynolds-averaged Navier-Stokes (RANS) flow simulation. The simulation shows that the tip leakage vortex formed close to the leading edge of the blade tip on suction side grows in the streamwise direction. On the casing wall, a separation line is formed upstream of the leakage vortex center due to the interference between the leakage vortex and main flow. The reverse flow is observed between the separation line and the attachment line generated downstream of the trailing edge, and increased with enlarging tip clearance. The patterns of a leakage velocity vector including a leakage flow rate are also analyzed according to two tip clearances. It is noted that the understanding of the distribution of a limiting streamline on the casing wall is very important to grasp the characteristics of the vortical flow in the axial flow fan.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.261-266
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• 2018

When the clamp meter approaches the electric path where current is flowing, leakage current can be measured at a distance from the electric current because the induced current increases as the magnitude of the current increases and approaches nearer to the electric path. Therefore, measurements were carried out from a distance to avoid this effect. In addition, the measured values differ depending on the location of the power line that penetrates the ZCT of the clamp meter, thus measurements were performed at a location where this effect was minimized. The fraction of compliant branch circuits, whose leakage current was lower than 1.00 mA, was found to be 69.0% out of the total of 439 branch circuits, while the percentage of compliant branch circuits having an insulation resistance higher than $0.20M{\Omega}$ was found to be 93.2%. The reason why the percentage of compliant branch circuits with low leakage current was low might be due to the inclusion of capacitive leakage current in the total measured leakage current.