• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.680-685
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• 2011

Nowadays, in metropolitan railroad, DC feeding system is being generally applied. In order to reduce damages of electro-chemical corrosion caused by stray current and leakage current, in DC feeding system, rail is used as negative-polarity return conductor for traction load current. However, it has problem of rail potential increase and there are no adequate measures to prevent it in domestic. In this paper, we presented fundamental theory and related standards about rail potential increase. And then, we analyzed field testing data and simulated a variety of operations by using PSCAD/EMTDC as an analysis program of power system. In addition, voltage control device is suggested to prevent accidents caused by rail potential increase.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.485-490
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• 2012

Nowadays, in metropolitan railroad, DC feeding system is being generally applied. In order to reduce damage of electro-chemical corrosion caused by stray current and leakage current, in DC feeding system, rail is used as negative-polarity return conductor for traction load current. However, it has problem of rail potential increase and there are no adequate measures to prevent it in domestic. The rise of rail potential leads to damage for human and equipments. To solve the problems, this paper presents fundamental theory and related standards about rail potential increase. And then, we analyzed field testing data and simulated a variety of operations by using PSCAD/EMTDC as an analysis program of power system. In addition, this paper suggests rail potential limit device and addresses how to the device. To verify the effect, simulation of DC feeding system before and after the application of the device is carried out in various cases.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.687-693
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• 2009

An algorithm and a computer software are developed for the analysis of rail potential rise. The algorithm is intended to be integrated with the traction power system simulation program. In the algorithm, rail potentials are obtained by two step process. First the injection currents to the negative rail are obtained from load-flow study. In the next step, a network consisting of negative rail and the injection currents are constructed. Leakage resistance to ground are added to the network. And the network is analyzed for rail potentials. A software is developed to verify the validity of the algorithm. The result of the software is compared with the Simulink/SymPower circuit analysis result. The differences between the two results are with the acceptable range. The advantage of this algorithm is that it can be integrated with the existing traction power supply simulation program easily, which usually ignores negative rail's leakage resistance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.577-583
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• 2013

We have analyzed influence of potential rise in negative bus, which caused by decrease of power feeding line insulation, upon protecting method of DC ground protection device which detecting potential rise between negative bus and ground in order to detect ground fault in the rubber wheel system. For this purpose, we proposed negative potential equation between negative bus and ground and calculated negative potential according to system condition changes by estimating power feeding line insulation changes in steel wheel system and rubber wheel system, and equalizing DC power feeding system when ground fault occurred. Also, in order to estimate negative potential of real system, we modeled the rubber wheel system, and simulated normal status, grounding fault occurrence and power feeding line insulation changes. In normal status, negative potential did not rise significantly regardless of vehicle operation. When ground fault occurred, negative potential rose up over 300V regardless of fault resistance. However, we also observed that negative potential rose when power feeding line insulation dropped down under $1M{\Omega}$. In conclusion, our result shows that in case of rubber wheel system unlike steel wheel system, relay will be prevented maloperation and insulation status observation can be ensured when ground over voltage relay will be set 200V ~ 300V.

• Steel and Composite Structures
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• v.36 no.4
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• pp.481-492
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• 2020

To study the rail mapped deformation caused by the pier settlement of simply - supported bridges with China Railway Track System III (CRTS III) slab ballastless track (SBT) system under the mode of non-longitudinal connection ballastless track slab, this study derived an analytical solution to the mapped relationships between pier settlement and rail deformation based on the interlayer interaction mechanism of rail-pier and principle of stationary potential energy. The analytical calculation results were compared with the numerical results obtained by ANSYS finite element calculation, thus verifying the accuracy of analytical method. A parameter analysis was conducted on the key factors in rail mapped deformation such as pier settlement, fastener stiffness, and self-compacting concrete (SCC) stiffness of filling layer. The results indicate that rail deformation is approximately proportional to pier settlement. The smaller the fastener stiffness, the smoother the rail deformation curve and the longer the rail deformation area is. With the increase in the stiffness of SCC filling layer, the maximum positive deformation of rail gradually decreases, and the maximum negative deformation gradually increases. The deformation of rail caused by the pier settlement of common-span bridge structures will generate low-frequency excitation on high-speed trains.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.138-146
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• 2010

DC railway power supply system generally uses the running rails as negative-polarity return conductor for traction load current, and the induced rail potential and stay current cause serious problems to any electrified matter in the underground and also safety problems to human body. This paper presents a new algorithm for the analysis of the rail potential and the stray current in DC railway power system operated under independent/parallel power feeding mode. The effect of load current fluctuation during train operation is also calculated by using TPS(Train Performance Simulation) program to analysis the variation of the railway potential and stray current along railway track. Simulation program is developed based on the proposed algorithm and case studies are provided.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.892-898
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• 2011

In DC electric railways, while an electric rail car is driving, a part of the working current returned to the substation through rails leaks into the ground. Such a stray current causes railway facilities and metal objects to corrode electrolytically. Therefore, change of stray current needs to be monitored constantly. But so far in domestic, the research on stray current measuring techniques and system adaption are insufficient. To estimate stray current, this paper addresses a method of monitoring the return current that is returned into the negative pole of the substation in real time.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.187-192
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• 2010

Korean railway has run about 110 years since 1989 and played a great role of industrialization in Korea. It is known that rail transport systems have many advantages of being more safe, energy-efficient, and environment-friendly, as compared to other transportation systems. However, railway incidents are often attributed to the failure of safety management and critical to the efficiency of railroad industry. This study reviewed economic, financial, and general statistical information on Korea Railroad. Based on the statistical data, the effect of accidents on railroad management was analyzed. Correlation analysis revealed that railway accident had a negative effect on the gross profit of Korea Railroad. In order to reduce potential risks and incident rate, some recommendations are proposed. Actual or potential applications of this research include safety guidelines for improving efficiency of railroad industry.