Dual electrification is a system whereby a railway line is supplied power both via overhead catenary and a third rail. This is done to enable trains that use either system of power to share the same railway line, for example in the case of mainline and suburban trains (as used at Hamburg S-Bahn between 1940 and 1955).[1]

A commuter train at a station. Below the train, four rails are visible—two are for the wheels and one provides power. Above the train, a catenary power line is also visible.
This photo shows an overhead catenary power line above the foreground train, and a third rail on the ground beside it.

Examples

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Germany

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Greece

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Norway

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United Kingdom

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United States

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Mainland China

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Variations

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Both systems live

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The system is usually used only in exceptional cases as it can lead to problems caused by the interaction of the electric circuits; for example, where one system is powered with direct current and another by alternating current (AC), premagnetisation of the substation transformers of the AC system can occur.

One system live

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A similar arrangement to dual electrification is one in which both means of powering a train are present, but not live simultaneously. Such arrangements can be found in frontier stations and in sections of railway used for running tests.

See also

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References

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  1. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2017-08-08. Retrieved 2017-08-08.{{cite web}}: CS1 maint: archived copy as title (link)