RU2579318C2 - Core for wire overhead power lines - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, namely to structures carrying cores uninsulated stranded wire for transmission of electrical energy into main high-voltage overhead lines and power networks designed for continuous operation. Core wires for overhead power lines in twisted cable includes bearing elements covered by metal sheath. Shell is made of solid aluminum or aluminum-zirconium alloy with tensile strength of 50-150 MPa, its inner surface is partially follows outer surface of cable to ensure their mutual contact area of 20-99 % of area of outer surface of cable and has thickness in thinnest places 0.2-2 mm, supporting elements have diameter of 1.0-4.5 mm. Core construction provides full protection of cable carrier members from exposure to atmospheric agents, and high corrosion resistance of wire.

EFFECT: it is possible to seal coils of conductive wires in wire manufacturing compact without impairing its mechanical and electrical properties.

5 cl, 1 dwg

Description

The invention relates to electrical engineering, and in particular to structures of bearing cores of uninsulated stranded wires for transmitting electrical energy in high-voltage air lines and electrical networks intended for long-term operation.

A known design of a multi-wire wire ("Non-insulated wires for overhead power lines" GOST 839-80), containing a core of galvanized steel wires and conductive wires of round aluminum wires laid on top of the core.

Such wires have sufficient electrical conductivity and mechanical strength, but during operation under the influence of external atmospheric factors and constant or variable loads (tension of wires, moisture, temperature changes, solar radiation, ice and wind loads, axial torsion of wires), zinc coating corrodes to 1 microns per year, as well as cracking and peeling of the zinc coating from the surface of the steel wires of the core. This leads to a reduction in the service life of the wire as a whole.

In addition, when densifying the wires from conductive aluminum wires along the ribbed outer surface of the steel core, there is a local squeezing of the conductive wires, leading to uneven cross-section of the wires along the length and, as a result, an increase in electrical resistance and local overheating at the places where the aluminum wires are pressed, and a decrease in the mechanical strength of aluminum wires and wires in general.

Known ACCC wire, consisting of a composite core from the company Composite Technology Corp. (STS) and aluminum foils laid over it (PCT application WO No. 2005/040017, B65H, Applicant Composite Technology Corp., USA).

The bearing core of this wire is made of two coaxially arranged composite materials. The central cylindrical part is made on the basis of carbon fibers impregnated with an epoxy binder. An annular layer of fiberglass, consisting of glass fibers impregnated with a high-temperature epoxy resin, is superimposed on top of the central part. The outer layer based on glass fibers protects the inner part of the core from contact with aluminum, preventing corrosion of carbon fibers and aluminum. The diameter of such a composite core is 5-11 mm.

Significant disadvantages of the STS core are:

- the core can be made only in the form of a rigid single-core rod of relatively large diameter, which is less preferable compared to a multi-core core in the manufacture, transportation, suspension of the wire and its further operation;

- the entire load during operation of the wire is perceived by almost one load-bearing element (core), which imposes increased responsibility on it;

- large bending radii due to the relatively large minimum diameter of a single supporting element, which requires the use of coils of large non-standard diameters at the stages of production and transportation;

- the need to use when installing wires with such a core of non-standard complex reinforcement, inaccessible to a wide consumer;

- exposure to weathering of the outer surface of the composite core, protected only by coils of aluminum wires;

- the inability of the core to participate in the transmission of electric current.

Known composite supporting core for external current-carrying conductors of wires of high-voltage overhead power transmission lines (RF patent No. 2386183 C1, НВВ 5/08, НВВ 13/02, publ. 04/10/2010), which is closest in technical essence to the patented invention and selected in as a prototype.

The core (patent of the Russian Federation 2386183) as one of the executions has a multicore structure twisted from long rods of high-strength continuously reinforced composite material. In one embodiment, the core comprises an outer metal shell rolled into an aluminum tape cylinder in a forming device.

The disadvantages of the known core include the following.

When applying a metal tape simultaneously with the formation of composite cores, deformation of the tape, incomplete closure of the tape and squeezing of the binder and reinforcing fibers through the gap of an incompletely closed metal tape are possible, which violates the continuity of the metal sheath.

The metal shell of aluminum tape is exposed to exposure under the influence of external factors (wind loads, heat heating, wire dance).

These two factors can lead to the destruction of the wire as a whole.

The disadvantages include the fact that the metal strip rolled into a cylinder touches the supporting composite core elements along an extended spiral line, and not along their outer surface. This leads to local loads on the core elements along the touch line during twisting and operation of the wire and can lead to deformation and destruction of the core elements.

Due to the localization of the load along the line of contact of the metal shell and the supporting composite core elements, compaction of the conductive wire fluffs with such a core design is impossible due to the threat of destruction of the supporting composite core elements having a low ability to withstand the load in the radial direction.

In addition, the installation of a wire with such a core should be carried out with special clamps to avoid mechanical destruction of composite elements.

The technical result to which the invention is directed is to increase the reliability of the core by increasing corrosion resistance, the ability to participate in the transmission of electric current, the ability to seal coils of conductive wires in the manufacture of a compact wire without compromising its mechanical and electrical properties, simplifying installation.

The technical result is achieved by the fact that in the core for the wires of overhead power transmission lines containing the supporting elements twisted into a cable covered by a metal sheath, the outer sheath is made of solid aluminum or of an aluminum-zirconium alloy with a temporary tensile strength of 50-150 MPa, its inner surface is partially repeats the outer surface of the cable with providing the area of their mutual contact 20-99% of the area of the outer surface of the cable and has a thickness in the thinnest places of 0.2-2 mm

Bearing elements of the inventive core can be made of composite material having a temporary tensile strength of at least 1100 MPa, or of steel galvanized or aluminum-clad wires.

The inventive core can be made with load-bearing elements with a diameter of 1.0-4.5 mm

In addition, the supporting elements of the core can be made on the basis of glass, carbon, basalt, boron, aramid, polyimide or ceramic fibers with the possibility of twisting them in a cable with a multiplicity of 10-25 steps. The invention is illustrated in the drawing, which shows the core in cross section.

The core contains a cable made of several twisted lengthy load-bearing elements 1. A continuous sheath 2 of aluminum or aluminum-zirconium alloy is applied over the cable, the inner surface of which partially repeats the outer surface of the cable and has a mutual contact area of 20-99% of its value. Moreover, the thickness of the shell in the thinnest places is 0.2-2 mm.

The invention provides for the use of two types of load-bearing elements 1.

According to the first type, the supporting elements 1 are made of a composite material including reinforcing fibers and a polymer matrix. According to the second type, the supporting elements 1 are made of galvanized or aluminum-clad steel wire, traditionally used in bare wires.

The manufacture of the central core cable is carried out by the method of twisting on traditional twisting machines with a twist.

The sheathing on the cable is carried out on traditional presses for applying smooth aluminum sheaths to cables or on conformal continuous pressing plants.

The lower boundary of the tensile strength of 50 MPa of the aluminum shell 2 is due to the fact that below this value the aluminum or aluminum-zirconium alloy is practically not annealed, or for this it is necessary to carry out the process at relatively high temperatures - 450-550 ° C, which can lead to thermal destruction composite supporting elements of the core.

An increase in the temporary resistance of the material of the outer shell 2 above 150 MPa leads to an increase in the efforts of pressing the shell, which can lead to mechanical destruction of the core elements if they are made of composite materials.

From the point of view of technological feasibility, the following ranges of temporary tensile strength of the shell of aluminum or aluminum-zirconium alloy are most preferred:

- 50-110 MPa - for the central cable of composite load-bearing elements;

- 90-150 MPa - for the central cable of steel supporting elements.

The lower boundary of 20% of the area of mutual contact of the inner surface of the aluminum shell 2 and the outer surface of the cable is due to the fact that at values less than 20% there is a localization of the load from external influences transmitted through the aluminum shell 2 only along a relatively narrow spiral strip of contact of the inner surface of the aluminum shell 2 and the outer surface of the supporting elements 1, which can lead to the destruction of the latter, made of their composite material, during installation of the wire and its operation. It is also possible slippage of the Central cable core relative to its outer shell 2 when the tension of the wire during its suspension and operation.

The upper limit of 99% of the area of mutual contact of the inner surface of the aluminum shell 2 and the outer surface of the cable is due to the technological capabilities of the equipment for applying continuous shells 2 of aluminum or aluminum-zirconium alloy, as well as the ability of composite load-bearing elements to withstand technological loads arising in the radial direction, when overlay aluminum shell 2.

The thickness of the sheath 2 of aluminum or aluminum-zirconium alloy in the thinnest places of 0.2-2 mm is due to the fact that at values less than 0.2 mm, it is possible to break through and violate the integrity of the sheath 2 in the manufacture of the wire, especially when applying a seal of conductive wires as well as during its installation. Also increases the likelihood of gaps and discontinuities at the stage of applying the outer sheath 2 to the cable during the manufacture of the core, as well as during bending of the core or wire with it, for example, when winding on coils and drums and winding from them.

When the thickness of the aluminum sheath 2 in the thinnest places is more than 2 mm, the likelihood of it bulging toward the inner radius with core bends, technological operations of winding the core or wire with it on coils and drums, especially with a small neck diameter, increases. The tensile strength of the core as a whole also decreases, and its outer diameter increases, which leads to an increase in the diameter of the wire and, accordingly, the wind loads acting on it.

The core for the wires of overhead power lines works as follows.

In the manufacture of a multiwire wire using the proposed core, external forces on the twist operation are perceived by the sheath 2, the inner surface of which partially repeats the outer surface of the cable with an area of mutual contact of 20-99% and a thickness in the narrowest places of 0.2-2 mm, and through it damped and transmitted to the outer surface of the cable twisted from relatively weak in the radial direction of the composite supporting elements 1, preventing them from damage. When steel wires 1 are used as the supporting elements 1, the core sheath 2 dissipates the load acting on the compaction operations on the round sealed wires of the conductive wires from the side of the ribbed surface of the cable from relatively strong steel bearing elements 1, preventing local transformation of the shape of the conductive wires.

When installing the wire using clamps of extruded or spiral types, external forces from them are transmitted through conductive wires to the aluminum sheath 2, which damps and evenly distributes the forces acting on them from the supporting elements 1 and preventing their destruction.

When using the proposed core in the wires of overhead power lines, its load-bearing elements 1, made of composite material or of steel galvanized or aluminum-clad wires, covering their aluminum sheath 2 with an inner surface partially repeating the outer surface of the cable with an area of mutual contact of 20-99% and a thickness of 0.2-2 mm in the narrowest places, they perceive the mechanical load acting on them of a different nature and ensure participation in the passage of electrical time.

Thus, the entire set of technical solutions and the corresponding selected materials used in the design of the proposed core, makes it possible to improve its technical characteristics by increasing corrosion resistance, the ability to seal conductive layers laid on top of the core without destroying its load-bearing elements, and to improve the ease of installation and repair work , which in general will increase the service life and operational reliability of the wires with the claimed core.

The stated essence of the invention indicates that it is based on a complex of new and original technical solutions, which determine the following advantages:

- provides complete protection of the cable from the supporting elements 1 from the influence of atmospheric factors and, as a result, increased corrosion resistance of the wire with such a core;

- the possibility has been realized of manufacturing compact wires with sealing according to coils without destroying the supporting composite elements of the core and without crushing the conductive wires on the ribbed outer surface of the central cable from steel supporting elements;

- provides the transmission of electric current through the shell 2 of aluminum or aluminum-zirconium alloy, which allows to reduce the cross section superimposed on top of the core of conductive coils of wire without reducing its throughput;

- the invention allows the use of widely used clampable and spiral clamps when mounting wires as tension and support clamps.

Claims (5)

1. The core for the wires of overhead power lines containing twisted support elements covered by a metal sheath, characterized in that the sheath is made of solid aluminum or aluminum-zirconium alloy with a temporary tensile strength of 50-150 MPa, its inner surface partially repeats the outer the surface of the cable with an area of their mutual contact of 20-99% of the area of the outer surface of the cable and has a thickness in the thinnest places of 0.2-2 mm, while the supporting elements have a diameter of 1.0-4.5 mm 2. The core according to claim 1, characterized in that the supporting elements are made of composite material having a tensile strength of at least 1100 MPa. 3. The core according to claim 2, characterized in that the supporting elements are made on the basis of glass, carbon, basalt, boric, aramid, polyimide or ceramic fibers. 4. The core according to claim 2, characterized in that the multiplicity of the pitch of the twisting of the cable from the supporting elements is 10-25. 5. The core according to claim 1, characterized in that the supporting elements are made of galvanized steel or aluminum-clad wires.

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