Contact network

A contact network can be of two types:

• Air contact network.
• Contact rails (not applicable on the trolley bus ).

Despite the fact that on rails, running rails are usually used to divert reverse traction current - as a rule, they are not considered as part of the contact network.

Components of the air contact network:

• Bearing cable
• Fittings
• Special parts for the contact network (intersections, arrows , sectional insulators )
• Reinforcing wire
• Contact wire

Pendant

The air contact network is suspended on various supports. In this case, between the suspension points, sagging of the contact wire is observed. A large sagging arrow harms the contact network, as the current collector moving along the contact wire may break away from the wire at the suspension points. At the moment of separation, an electric arc forms between the current collector and the wire. Contact restoration occurs with a shock of the current collector about the wire. Rocking of current collectors also occurs. These phenomena accelerate the wear of the contact wire and current collectors, worsen the quality of current collection, and also create radio interference. Avoid these phenomena allow:

• Elastic suspension. At the same time, passing the suspension point, the current collector raises the suspension.
• Wire tension adjustment to reduce sagging boom. Adjustment can be carried out either manually, twice a year, or automatically, using counterweights. Some types of pendants, for example, pendulum, do not require special devices to adjust the tension.

The most common types of pendants:

• A simple contact suspension is a wire hanging freely between the suspension points located on the supports. Currently used only for the contact network in quarries, as well as for tram lines.
• Cross-chain contact suspension - the contact wire between the supports of the contact network does not hang freely, but on frequently located wires, called strings, which are attached at the other end to the support cable.
• Longitudinal-chain contact suspension - a longitudinal cable is suspended along the track, suspended on rigid or flexible crossbars. A contact wire is suspended from it using strings. Such a suspension is very elastic. Thanks to this, the contact wire wears out less, which extends its service life.
• Spatial-diamond-shaped contact suspension - has two load-bearing cables and two contact wires. Contact wires form in the plan rhomboid shapes symmetrical about the axis of the path. Bearing cables are located on both sides of the path axis and are rigidly fixed to the horizontal console of a single support or to a rigid cross-beam at the suspension points through insulators. Span temperature compensation of this type of suspension eliminates longitudinal displacement and provides better dynamic characteristics of the contact network than vertical suspensions. It has particular advantages during installation in tunnels due to the small vertical dimensions ^[1] .

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  Simple contact wire suspension at the Estación de Callao Madrid Metro Station

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  Scheme of a longitudinal-chain suspension: A - suspension points, B - bearing cable, C - strings, D - contact wire

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  Variants of the relative position of the support cable (red) and the contact wire (blue) relative to the axis of the path

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  Dynamic contact wire tension with blocks and counterweights (compensators)

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  Two-phase contact network for three-phase electrification (3rd phase on rails)

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  KS-321 clamp for connecting contact wire joints

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  Double contact wire suspension clamp

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  Contact network and current collector of a children's circuit

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  Suspension of trolleys in the Experimental pool SPGUVK

Contact wire

The contact wire is suspended in a horizontal plane in a zigzag manner with a deviation of ± 300 mm from the longitudinal axis of the track (for a track of 1520 mm), which increases its wind stability and reduces wear on current collectors (due to more uniform contact along their entire length) ^[2] . Contact wires are made of hard-drawn electrolytic copper or from more expensive and wear-resistant copper - cadmium and copper- magnesium alloys . More rarely, bimetallic contact wires, such as copper with a steel core, aluminum-steel with a steel contact surface, can be used. Suspension strings are usually made of steel-copper wires, bearing cables - of copper, steel-copper, steel-aluminum stranded wires.

Contact rail - a hard contact wire designed to make sliding contact with the current collector of rolling stock ( electric locomotive , motor car).

Made of mild steel, the shape and transverse dimensions are similar to the shape and dimensions of conventional rails. The rail is fastened with insulators to the brackets, which, in turn, are mounted on the sleepers of the running rails.

To ensure the possibility of supplying the contact network from several traction substations , as well as to repair individual sections without disconnecting the entire contact network, sectioning of the contact network is used . In this case, the contact network is divided into sections - the so-called. sections. Each section is powered by a separate feeder from the traction substation . In the event of a malfunction at the traction substation ( or feeder damage ), it is usually possible to power the section from another traction substation . Thus, the partitioning increases the reliability of the contact network, ensuring uninterrupted supply of electricity.

Section Isolation

To ensure reliable isolation of sections and prevent the formation of an arc , which can violate the isolation between sections when current collectors pass from one section to another, sectional insulators are used .

The distance of the contact network is responsible for the operation of all elements of the contact network in the operating areas, their maintenance and repair on the railway.

In December 2003, the Department of Electrification and Energy Supply of Russian Railways OJSC issued an instruction on the use of thermal diffusion galvanizing of parts and structures of a contact network. This manual applies to protective zinc coatings applied by thermal diffusion galvanizing to threaded parts, fittings, contact network designs and other products of carbon and low-carbon steel, including high strength, to cast iron parts of the contact network, including cast-iron terminators of porcelain insulators.

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  Contact network on a stretch electrified by alternating current 25 kilovolts

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  Contact network at a station electrified with alternating current 25 kV

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  Contact network arrow over turnouts , DC electrification 3 kV

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  Contact network on the curves of the stretch electrified with direct current 3 kV

• Contact network of a trolley bus
• Chain contact suspension
• Contact Section Section
• Traction substation
• Energy train

• Contact network // Big Soviet Encyclopedia : [in 30 vol.] / Ch. ed. A.M. Prokhorov . - 3rd ed. - M .: Soviet Encyclopedia, 1969-1978.
• Freifeld A.V., Brod G.N. Contact network design . Ed. 3 (additional and revised) // M .: Transport, 1991 - 334 p.
• Mikheev V.P. Contact networks and power lines // Textbook for universities. - M.: Route, 2003 .-- 416 p. ISBN 5-89035-086-2
• SNiP 2.05.09-90 “Tram and trolleybus lines”
• GOST 23476-79 “Tram and trolley bus contact network fittings. General specifications "