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The current collection device presses against the underside of the lowest wire of an overhead line system, which is called a contact wire. Most overhead supply systems are either DC or single phase AC, using a single wire with return through the grounded running rails. Three phase AC systems use a pair of overhead wires, and paired trolley poles.
Conduit for current collection between the rails of streetcars in Washington, D.C., 1939. Washington installed the system in 1895 [ 1 ] and it remained in operation until 1962 [ 2 ] Conduit current collection is an obsolete system that was used by some electric tramways to pass current to streetcars via a "conduit", a small tunnel under the ...
It is a type of current collector. The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J. Sprague, [1] but the first working trolley pole was developed and demonstrated by Charles Van Depoele, in autumn 1885. [2] Machining spare trolley pole wheels
As the train moves, the contact shoe slides along the wire and can set up standing waves in the wires which break the contact and degrade current collection. This means that on some systems adjacent pantographs are not permitted. A Flexity Outlook LRV with its pantograph raised. Note the trolley pole in the rear, which provides compatibility ...
To achieve good high-speed current collection, it is necessary to keep the contact wire geometry within defined limits. This is usually achieved by supporting the contact wire from a second wire known as the messenger wire or catenary .
The bow collector is one of the simplest and most reliable methods of current collection used on tramways. The very earliest versions were simply very heavy-gauge wire or steel bars bent into a rectangular shape and mounted long-side-down on the tramcar roof. The collector was then raised by a spring, so that its top edge would press against ...
Seville Tram equipped with CAF ACR ground-level power supply, 2019. Ground-level power supply, also known as surface current collection or, in French, alimentation par le sol ("feeding via the ground"), is a concept and group of technologies that enable electric vehicles to collect electric power at ground level instead of the more common overhead lines.
Two current collectors are required in order to supply and return current, because the return current cannot pass to the ground (as is done by streetcars on rails [2]) since trolleytrucks use tires that are insulators. Lower powered trucks, such as might be seen on the streets of a city, tend to use trolley poles for current collection.