捷運系統之車行鋼軌，除扮演支撐車體與導引列車行駛方向的角色外，亦多兼具列車牽引電流之負回流路徑功能。當列車負回流經車行鋼軌流回變電站時，鋼軌將因自身的電阻而於其上產生壓降，此壓降使鋼軌對地存在電位差，稱之鋼軌電位昇(Rail Potential Rise)。臺北捷運系統不論是機廠軌道或主線軌道，在設計上，牽引電力之正電及負電均是分開的，而此不同區間之鋼軌則在機廠邊界與正線交界處，透過鋼軌夾膠絕緣接頭(以下簡稱I.R.J.)加以隔離。因I.R.J.兩端之鋼軌因分屬不同的牽引電力系統，故在I.R.J.兩端存有經常性之電位差(-50V DC與+200V DC之間)，當電聯車進出機廠區且跨越此I.R.J.處時，每逢電聯車鋼輪在離開I.R.J.端鋼軌之瞬間，將在鋼輪與鋼軌接觸面間產生電弧，此電弧造成電聯車鋼輪面與I.R.J.兩端鋼軌面發生電焊侵蝕現象。
日前在捷運新店機廠小碧潭站端附近，發現鋼軌對地電位有偏高現象，且電聯車鋼輪面與主線及機廠間之鋼軌面間，電焊侵蝕現象有日趨嚴重之情形，為徹底解決捷運運輸之潛在危機，經臺北市捷運工程局相關單位，參考國外先進工業國家之案例，提出加裝電位差改善設備之方案。
本研究係針對上述電弧改善設備，在設計、製造、安裝及運轉過程中，是否能夠依捷運局技術規範之需求，在契約規定之180天可靠度驗證期間內，當電聯車行經主線與機廠間之IRJ處時，就設備切換形情及電弧消除之狀況加以分析。並自可靠度驗證測試報告中，萃取相關佐證資訊加以研析，於末來捷運路網興建時，在電弧改善方面還有那些事項，提出建議及改善方式。

Electrical power for Taipei Metro system EMU, supplied by Taiwan Power Company (TPC) to the Metro System Engineering Department at a potential of 161kV, following receipt by Bulk Supply Substations (BSS) managed by the Department of Rapid Transit (DORT), is stepped down from 161kV to 22.8kV and distributed to downstream Traction Supply Substations (TSS). The TSS, after transforming and rectifying this 22.8kV AC power into 750V DC power, supply positive current to downstream conductor rails to serve as an EMU motive power source. Negative current, after use by the EMU, flows to the running rail via its wheels and returns to the TSS negative bus, completing the DC circuit.
The running rails in a rapid transit system, apart from supporting and guiding the car body, also serve as the traction current return path. Negative EMU current returning to the TSS via the wheel and running rail undergoes a voltage drop (called Rail Potential Rise) due to the electrical resistance from the rail. Whether the rail is located in the DORTS depot or in the main line, the negative and positive traction power current are by design separated, and in the area depot boundary and the main line, Insulated Rail Joint (IRJ) are used to increase the separation. Since the rail between the two extremities of the IRJ belongs to different power systems, there usually exists a potential difference (-50V DC to +200V DC). Each time the EMU wheel leaves the IRJ, an arc will be produced between the wheel and the rail, leading to corrosion between the EMU wheel and the tracks.
Recently, DORTS found the electric potential in the vicinity of Hsiao Pitan Station to be on the high side and the corrosion between the EMU wheel and rails of two extremities of IRJ becoming more serious daily, so in order to thoroughly eliminate this potential risk, relevant units of the DORTS Engineering Department, after considering examples from other advanced industrialized countries, proposed a plan to install equipment to ameliorate the electric potential difference.

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