捷運直流牽引系統所衍生的雜散電流，在不同的接地系統有不同的防治作為。本文先闡述高雄捷運電力系統架構、變電站配置、負載規劃進而說明直流牽引動力變電站的架構、直流電壓與負載變化關係。再者雜散電流對於軌道、軌道扣件及地下金屬管線的影響。
高雄捷運直流牽引系統採用非接地系統，透過軌道電位評估軌道絕緣特性。鋼軌電位記錄電腦透過SCADA系統存取捷運各車站即時的鋼軌電位數值，藉由圖控軟體將鋼軌電位資料以圖像方式展現，依此建立鋼軌電位異常檢核機制進行查核。文末也提出相關成果案例作為討論，該成果案例展現出鋼位電位於非接地直流牽引系統之軌道絕緣特性管控上的成效。

For stray current issues in MRT DC traction systems, the prevention schemes in different grounding systems are different. The power systems in Kaohsiung MRT system are introduced first, including substation arrangement, load distribution, traction substation architecture, and voltage regulation in the traction substation. Following that, the influences of stray current on the rail fastenings and underground metal pipes are presented. Being a non-grounded DC traction system, insulation of Kaohsiung MRT system is assessed based on rail potential analysis. The station rail potential values are collected from SCADA system via rail potential recording computer in the form of statistical plots. The abnormal events on rail potential can thus be detected. Finally, case studies on rail potential of abnormal events and the effectiveness of the insulation assessment are discussed for the non-grounded DC traction system.

[1] J.G. Yu, “The effects of earthing strategies on rail potential and stray currents in DC transit railways”, International Conference on Developments in Mass Transit Systems, IEE, April 1998, pp. 303-309
[2] C.H. Lee and H.M. Wang, “Effects of grounding schemes on rail potential and stray current in Taipei rail transit systems”, IEE Proceedings - Electric Power Applications, 2001, 148, (2), pp. 148-154
[3] J.G. Yu and C.J. Goodman, “Modelling of railway potential rise and leakage current in DC rail transit systems”, IEE Colloquium on Current Effect of DC Railways and Tramways, Digest No. 129, London, 1990
[4] C.S. Chang, W. Wang, A.C. Liew and F.S. Wen, “Bicriterion optimisation for traction substations in mass rapid transit systems using genetic algorithm”, IEE Proceedings - Electric Power Applications, 1998, 145, (1), pp. 49-56
[5] K.D. Pham and R.S. Thomas, “Analysis of stray current, track-to-earth potentials & substation negative grounding in DC traction electrification system”, IEEE/ASME Joint Railroad Conference, Toronto, Canada, April 2001, pp. 141-160
[6] R.S. Thomas and K.D. Pham, “Design of grounding systems for TRI-MET Portland Westside light traction power substations”, IEEE/ ASME Joint Railroad Conference, Dallas, TX, USA, 1999
[7] B.Y. Ku, C.Y. Lee, K.H. Yen, J.J. Yang and C.F. Lin, “Touch potential and stray current of diode grounded DC traction systems”, Proceedings of the 19th Symposium on Electrical Power Engineering, 1998, pp. 677–681
[8] L.H. Schwalm and J.G. Sandor, “Stray current - The major cause of underground plant corrosion”, Materials Performance, Vol. 6, 1969
[9] Thomas J. Barlo and Alan D. Zdunek, “Stray current corrosion in electrified rail systems”, Published online at: http://iti.acns.nwu.edu/projects/ stray1_int.html, May 1998
[10] J.G. Yu and C.J. Goodman, “Stray current design parameters for DC railways”, IEEE Joint Railroad Conference, Atlanta, CA, USA, 1992, pp. 19–28
[11] K.S. Bahra and R.B. Catlow, “Control of stray currents for DC traction systems”, IEE International Conference on Electric Railways in a United Europe, 1995, pp. 136–142
[12] K.J. Moody and P.E., “Stray Current Characteristics of Grounded, Ungrounded, and Diode Grounded DC Transit Systems”, CORROSION/94, No. 589, National Association of Corrosion Engineers, Baltimore, Maryland, March 1994.
[13] P. Todd, “BART Stray Current Prevention”, CORROSION/94, No. 587, National Association of Corrosion Engineers, Baltimore, Maryland, March 1994.
[14] H. Bomar, R. Dean, J. Hanck, M. Orton and P. Todd, “Bay Area Rapid Transit System (BART)”, Materials Performance, Vol. 13, No. 12, December 1974, pp. 9-17.
[15] 李美蘭，「台北捷運系統淡水-新店線車行軌道之接觸電位分析」，碩士論文，2000年，P54-98
[16] M.J. Szeliga and P.E., “Stray Current Control Through Storage Yard Isolation The WMATA Experience”, CORROSION/84, No. 157, National Association of Corrosion Engineers, New Orleans, Louisiana, October 1984.
[17] G.C. Welch, “The Metropolitan Atlanta Rapid Transit System: From the Utility Side”, CORROSION/82, National Association of Corrosion Engineers, Houston, Texas, March 1982.
[18] M.F. Merrick, “Stray Current Control Metropolitan Atlanta Rapid Transit Systems”, CORROSION/82, No. 296, National Association of Corrosion Engineers, Houston, Texas, March 1982.
[19] W. Sidoriak and P. Deleuw, “DC Transit Rail Isolation Design, Installation and Problem Resolutions on the Baltimore Central Light Rail Line”, CORROSION/93, No. 591, National Association of Corrosion Engineers, New Orleans, Louisiana, June 1993.