• International Journal of Railway
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• v.3 no.2
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• pp.46-53
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• 2010

Electric railroad systems consist of rolling stock, track, signal and catenary system. In the catenary system, one of the most important factors is the impedance according to the design and characteristic. Before the catenary system is designed, the impedance should be precedently researched. The railroad catenary system is complex system which is composed by five conductors. The five conductors classify up and down feeders, up and down contact wire group, rail group. Therefore, we should compose the catenary system of the equivalent five-conductors model. In this paper, we suggest a geometrical model and a equivalent conductor model by using geometric mean radius of five conductors in the catenary system. Also, we calculate demanded parameter values in the model. By using those, line constants of five conductors are analyzed by applying the equivalent method called as the condensed joint matrix.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.125-127
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• 2005

This paper conducted to evaluate electrical continuity of steelworks within reinforced concrete apartment structures as the down conductor in external lightning protection system. The reinforcing bars in reinforced concrete structures can be used as the down conductor when their overall electrical resistance is not greater than the resistance value of 0.2 ohm between the uppermost part and the ground level. According to the results of electrical resistances measured by 4-terminal low resistance measurements, the steelworks in reinforced concretes structures exhibited the electrical continuity with low electrical resistance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.101-107
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• 2013

IEC Standards on lightning protection system specify the use of natural components as down conductors. This paper provides an analysis of problems revealed from our field investigation and survey conducted for the relevant experts in the construction site where natural components are used as down conductors. It also considers a suitable condition for installing natural components as down conductors in accordance with the latest version of the standard. As a result, when rebars of reinforced concrete are used as down conductors, vertical bars consisting of rebars of which thickness is not less than D13($127mm^2$) should be connected by welding, clamps or bound joints, using appropriate connection components conforming to IEC Standards. The lashed joints, however, shall not be applied for down conductors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1730-1741
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• 1997

In this paper, we developed a surface profile measuring system and a profile measuring software for EGL conductor roll. For the profilemeter, we designed a linear guided control system with Laser displacement sensors and developed a 3-dimensional software. Additionally, the AC motor and AC motor driver were used to control the precise position of linear guide system. The measuring principle of the Laser sensor is optical triangulation method. Also, two Laser sensors were used to remove the disturbance and vibration effects of the linear guide system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.4
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• pp.73-80
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• 2013

Breakdown characteristics of air in the vertical arrangement of line conductor and plane electrode in case of combustion flame on the plane electrode are examined by the application of AC. and DC voltages to the gap. In order to investigate the effect of paraffin flame on the breakdown characteristics of air, flashover voltages are measured according to the variation of the gap length and the horizontal distance between the flame and the line conductor. As the result of the experiment, flashover voltages are substantially lowered down to 29.8% in case of the AC voltage, and 16.1% in case of the negative DC voltage, when in the presence of the flame. from 100% when in the absence of flame. Flashover voltages of air in the range of smaller than 3㎝ at the horizontal distance are increased in the proportion of the gap length and the horizontal distance in case of both AC and negative DC voltages. But before the flashover occurs, the flame is extinguished by such corona wind that is produced from the line conductor when the gap length and the horizontal distance reach to a certain degree. The effect of relative air density and the phenomenon of thermal ionization are analysed as the reduction factors of flashover voltages, due to high temperature of the flame.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1674-1676
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• 2003

The factors affecting the accuracy of lightning current measuring system are figured out the materials and length of down-conductor, and impedance matching between grounding resistance and characteristic impedance of cable. The cable with the low characteristic impedance used to transfer the lightning current from the top of the tower is too long to measure the waveform of lightning current, exactly. Especially, the height of the tower can cause the change of front time and magnitude of lightning stroke current. Basically, in this experiment. It was found that the magnitude and rise time of the lightning current are extremely dependant in the length of down-conductor in lightning current measuring system.

• Progress in Superconductivity
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• v.10 no.2
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• pp.149-154
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• 2009

We measured and analyzed the quench development in coated conductor(CC) tapes. The CC was grown on hastelloy substrates and has an Ag protection layer. The tapes were subjected to simulated AC fault currents for quench development measurement. They were immersed in liquid nitrogen during the experiment. The quench resistance increased rapidly first, and the increase slowed down afterwards. It increased linearly with applied voltage at lower voltages, and depended less strongly on applied voltage at higher voltages. The resistance was compared with that of Au/YBCO films grown on sapphire substrates, and found to increase more monotonously than the latter. Data were analyzed quantitatively with the concept of heat transfer within the tape and the surrounding liquid nitrogen. A heat balance equation was derived and solved, taking into consideration temperature dependence of thermal parameters of the tapes. Solutions, together with values of thermal parameters taken from the literature, explained the data well. Cooling by liquid nitrogen affected the quench development considerably at lower applied voltages. Dependence on applied voltages could be also understood quantitatively.

• Economic and Environmental Geology
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• v.35 no.6
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• pp.567-573
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• 2002

Two-dimensional MT (Magneto-Telluric) modeling is performed to verify the validity of difference arrow for GDS(Geomagnetic Depth Sounding) survey. The electromagnetic mutual coupling between the sea and in-land conductor is used as a criterion that judges the validity of difference arrow. In this study, the mutual coupling between them is examined according to the spatial distance between them and the period of magnetic variations. The difference arrow is valid for conductors located at surface which are far from the sea or when the long period is used, but the mutual coupling is weak for buried conductor in all the periods. However, when a conductor extends vertically down to the deep part, the validity of difference arrow is in doubt, since the strong mutual coupling influences up to the long period. Therefore, to remove the known conductor effect such as sea effect from the observed induction arrow, the mutual coupling between them must be examined and the caution must be exercised in interpreting the resultant difference arrow if mutual coupling between them is strong.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.271-273
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• 2005

In this paper, The experiment is performed for using reinforced building of foundation as a down conductor and a substitutional earth electrode. It is shown that earth resistance is influenced by mortar block resistance and concrete resistance more than the change of the resistance which is about steel reinforcing volume in all of the mortar block model and concrete block model.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2020-2022
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• 2000

The cross-linked polyethylene(herein after XLPE) insulated power cable emit the methane($CH_4$)gas in the course of chemical cross-linking process. The general stranded conductor easily discharge this methane gas through the gap of each stranded wires. But the special stranded conductor that filled with semi-conducting rubber compound to prevent water penetration which is applied to water proof type of cable(22.9kV CN/CV-W), disturb the methane gas emission. The pre-mold type cable joint shall be expanded gradually by emit of gas left in XLPE insulation. For example, sometimes the corona problem outbreak on a new power distribution line, resulted from the gap between the sleeve and semi-conductive layer of cable joint. If above mentioned problem especially happened on the way of operating. We have to shut down the line and try to discharge the methane gas in cable joint. In this point, we would like to explain the mechanism of methane gas & cable joint and our test result briefly. At last, we are pleased to introduce the solution for preventing reoccurrence of this problem.