Overview of Feeding Systems

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In an AC Feeding System, a portion of the return current leaks from the rails to earth via the sleepers, thereby causing an inductive obstruction in telecommunication lines.

Therefore, not only a countermeasure on the telecommunication line side, but also a countermeasure on the feeding circuit side for limiting the section in which the return current flows to the rail is taken.


The BT Feeding System which uses a Booster Transformer (BT) as a countermeasure in the feeding circuit was adopted at the time of opening the First Shinkansen (Tokaido Shinkansen).


However, the Traction Substation terminal voltage is then low, the Traction Substation interval is inevitably short, a BT must be provided every 4 km, and an arc is generated by the pantograph in a BT section, and this becomes a drawback in maintaining the overhead contact line.

For these reasons, since the Sanyo Shinkansen has started commercial operation, the AT Feeding System using an Auto Transformer (AT) has been adopted.


BT Feeding System is Japanese name, this is called "Booster Transformers/Return Conductor System (BT/RC System)" globally.

AT Feeding System is Japanese name, this is called "2x25 kV Traction System" globally.

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