RU2338279C2 - Electric communication cable - Google Patents

Abstract

FIELD: communications.

SUBSTANCE: cable contains internal conductor in polymeric insulation, external conductor, at that, specified conductors have equal values of electrical direct-current resistance, and sheath made of three layers, the middle of which is made of reinforcing filaments and the other two are made of polymeric mixture. Electric communication cable also can consist of at least two mentioned cables sealed into common protective sheath over which layer of water-proof material, armor consisting of circular steel wires and moister-protective polyethylene hose can be applied.

EFFECT: provides minimal attenuation of low-frequency signals, control signals, signalisation and low-voltage electric power supply with simultaneous maintaining the attenuation coefficient for high-frequency signals.

2 dwg, 2 tbl

Description

The invention relates to the cable industry and can be used in the construction of communication and signaling cables, in particular, subjected to significant tensile and crushing loads.

Communication cables that provide operation under conditions of tensile loads, belong to the group of field cables.

Cable products of the P-274M and P-268 brands are known, manufactured according to TU 16-505.221-78 (Information and Technical Collection "Cable Products, Volume 2, Cables, Wires and Cords of Communication, Part I" Moscow, JSC "VNIIKP"). P-274M and P-268 have flexible combined cores twisted from copper and steel wires, which allows them to be suspended on poles or local objects. However, no protection against crushing forces is provided. P-274M and P-268 have a design symmetrical with respect to electrical parameters: two identical conductive conductors, insulated with polyethylene, twisted in a pair. But mechanically in the radial direction, a symmetric pair is not the best solution. It is well known that to counter radial loads, an axisymmetric design is usually used, in other words: coaxial.

Known cables are brands P-296 and P-296M, manufactured according to TU 16-505.293-81. These are cables with copper conductive conductors insulated with polyethylene and twisted into a four, with a shield in the form of a coil of copper wires, with a sheath of polyethylene, with a winding in the form of two coils of tinned steel or galvanized wire in a protective hose made of PVC plastic. This cable can withstand radial loads, but due to the large mass it is inconvenient for suspension and for multiple laying.

Symmetric cables of the P-269M grade of three, five, ten and twenty-pair cables with insulation and a sheath of polyethylene and a load-bearing element of technical threads are also known. They are subject to requirements for tensile and crushing forces. However, the pair symmetrical design does not provide sufficient resistance to radial crushing influences.

The closest in combination of features to the present invention is a flexible radio frequency cable (patent for utility model RU No. 50706 dated 08/26/2005) having a flexible inner conductor twisted from soft copper or tinned copper wires, coated with insulation from foamed polyethylene, an outer conductor in the form of a braid made of soft copper or tinned copper wire, on top of which a layer of water-blocking material is laid, and then a moisture-proof sheath of thermoelastic material.

This cable has an axisymmetric coaxial design, but it does not provide resistance to tensile forces and there is no symmetry at low frequencies in terms of electrical resistance to direct current of the internal and external conductors.

The problem solved by the proposed invention is the creation of an electric communication cable, providing conditions for the simultaneous transmission with physical separation of the communication channels of high-frequency and low-frequency signals, control signals, signaling and low-voltage power supply, and minimal attenuation of low-frequency signals, control signals, signaling and low-voltage power supply while maintaining attenuation coefficient of high-frequency signals and providing resistance to tensile and crushing mechanical stress, bending and abrasion.

The technical result is achieved in that in an electric communication cable including an inner flexible conductor of twisted soft metal wires coated with polymer insulation, an outer conductor and a polymer sheath, the inner and outer conductors have the same value of electrical resistance to direct current, and the sheath is made of three layers, moreover, the middle one is made of reinforcing threads, and the other two are made of a polymer composition based on thermoplastic elastomer, and the insulation is made of a polymer composition.

Depending on the level of crushing effects, it is advisable to use the wires used for the manufacture of internal and external conductors from the range: soft copper, combined soft copper and steel, bimetallic steel-copper. To simplify the soldering technology, tinned copper wires can be used instead of soft copper.

Also, depending on the level of crushing effects, it is advisable to choose insulation from a number of compositions based on: foamed polyethylene, a foamed composition based on thermoplastic elastomer, a continuous composition based on thermoplastic elastomers, a continuous composition based on continuous polyethylene.

To ensure the multiple deployment and coagulation of mobile communications at negative ambient temperatures up to minus 50 ° C, it is advisable to make polymer shell layers from a composition based on thermoplastic elastomer.

To protect against electromagnetic interference, a screen is laid over or under a layer of reinforcing threads. For the convenience of installation, a screen wire is laid under the screen.

For long-term laying of single-axial and multi-axial cables directly into the ground, it is advisable to lay a layer of water-blocking material, armor from round steel wires and a moisture-proof polyethylene hose over the protective polymer sheath.

To ensure stable operation of the cable in the high frequency range, it is advisable to lay a metal-polymer tape with the metal up under the outer conductor with overlapping.

The equality of the values of the electrical resistance of the internal and external conductors can be ensured, in particular, by selecting the number of wires and the pitch of their application.

To ensure the simultaneous parallel installation of several telephone lines, it is advisable to use a cable (multi-pair) containing several, at least two, coaxial-type communication cables placed in a common protective polymer sheath.

In this case, at least two of these cables in a common sheath can be twisted into a core.

The protective polymer shell can be made three-layer. Moreover, the middle layer is made of reinforcing threads, and the other two are made of a composition based on thermoplastic elastomer that does not spread combustion.

A layer of water-blocking material, armor made of round steel wires and a moisture-proof polyethylene hose can be sequentially applied over the protective polymer shell.

The invention is illustrated by drawings, in which a sectional view of a cable is shown: a cable according to claims 1 to 9 (Fig. 1) and a cable according to claim 10 (Fig. 2).

The electrical communication cable 1 of the coaxial type (Fig. 1) consists of an inner conductor 2, a polymer insulation 3, a metal-polymer tape 4, superimposed overlapping with the metal upward, an outer conductor 5, made of wires by winding in a spiral or braid, the first polymer layer of the sheath 6, the screen wire 7, the screen 8, a layer of reinforcing threads 9 and the last 10 polymer layer of the sheath.

The multi-axial electrical communication cable (FIG. 2) consists of several coaxial cables 1, a protective polymer sheath 11, a layer of water-blocking material 12, armor 13 and a polyethylene hose 14.

The following is evidence of the industrial applicability of election.

Cable manufacturing technology is as follows

Copper wires for the manufacture of internal 2 and external 5 conductors are made of copper wire, usually with a diameter of 8 mm, by drawing. Depending on the diameter of the resulting wire, the following operations can be used: coarse and medium drawing or coarse, medium and fine drawing. Steel and bimetallic wires are purchased ready-made of the required diameter.

Un tinned copper wires are annealed to provide softness. Annealing is not required to obtain tinned veins. Tinning is done in a hot way, as a result of which the core becomes soft.

The inner conductor 2 is twisted from separate wires on a cigar or frame type machine.

Insulation 3 is applied by extrusion from a granular polymer.

The outer conductor 5 is superimposed by winding or braiding on winding or braiding machines. In the same operation, a metal-polymer tape 4 is applied.

The polymer layers of the shell 6 and 10 are applied by extrusion from a granular polymer.

The screen 8 can be made of metal-polymer tapes or soft copper or tinned copper wires. Metal-polymer tapes can be applied by spiral winding on winding machines or longitudinally in operations of applying a layer of reinforcing threads or the last layer of a polymer shell during extrusion.

A screen of wires can be superimposed by winding on a wrapping machine or braiding on a braiding machine.

The screen wire 7 in combination with the copper screen 8 is made in the form of a soft copper wire in combination with an aluminum screen - in the form of a tinned copper wire can be laid straight and zigzag, previously curved (corrugated) on a special device. In some cases, the screen wire is made flexible multi-wire.

The manufacturing technology of the screen wire is the same as the manufacturing technology of the inner conductor.

A layer of reinforcing threads 9 is applied by winding on a winding machine or by braiding on a braiding machine.

The core of a multi-pair cable is made by twisting on single-pair cable machines lantern type 1.

A protective shell 11 made of thermoplastic elastomer, which does not spread combustion, is applied over the core by extrusion from granular material.

A layer of water-blocking material 12 is superimposed on the protective shell 11 by winding in a spiral fashion on a winding machine or longitudinally for booking operations.

Round wire armor 13 is applied by spiral winding on an armor machine or by braiding on a braid machine.

Moisture-proof polyethylene hose 14 is applied by extrusion from granular polyethylene.

To confirm the technical result, samples of an electric cable 1 of coaxial type were made.

Two samples No. 1 and No. 2 are made with approximately equal electrical resistance of the external and internal conductors to direct current, sample No. 3 - with an electric resistance of the internal conductor less than that of the external one. The results of measurements of electrical parameters are summarized in table 1.

Table 1 Sample Number Electrical resistance to direct current Ohm per 1 km of conductors Electrical resistance to alternating current of a coaxial pair at a frequency, Ohms per 1 km DB / km attenuation at frequency 800 Hz 10,000,000 Hz 800 Hz 10,000,000 Hz ext. ext. one 34.14 34.77 68.93 479.51 1.13 65.11 2 34.51 34.43 68.96 488.23 1.17 64.88 3 34.33 59.33 93.69 469.95 1.41 65.05

The samples were subjected to tensile and crushing tests, the results are presented in table 2.

table 2 Sample Number Tensile force, kN Radial Compression, kN / cm Normalized for the well-known cable P-269 M Test gap Normalized for the well-known cable P-269 M Test Crush one 1.73 0.77 2 1,2 1.88 0.45 0.73 3 1,69 0.75

As can be seen from table 1, the attenuation coefficient at a frequency of 800 Hz for samples with equal electrical resistance to direct current of the internal and external conductors are the same within the measurement error, and for a sample with unequal resistance to conductive DC current, the attenuation coefficient at the same frequency is about 20% higher . At a frequency of 10,000,000 Hz, the electromagnetic field practically does not penetrate the metal, and the attenuation coefficient of all samples coincides within the measurement error. This confirms the achievement of the technical result.

Claims (15)

1. The coaxial type electric communication cable, including an inner conductor coated with polymer insulation, an outer conductor and a polymer sheath, characterized in that the inner and outer conductors have an equal value of electrical resistance to direct current, the sheath is made of three layers, the middle of which reinforcing threads, and the other two of the polymer composition. 2. The cable according to claim 1, characterized in that the inner conductor is flexible, twisted from soft metal wires, and the outer conductor is made in the form of a sheath or braid of soft metal wires. 3. The cable according to claim 1 or 2, characterized in that the insulation is made of a continuous or foamed composition based on polyethylene. 4. The cable according to claim 1 or 2, characterized in that the insulation is made of a solid or foamed composition based on thermoplastic elastomer. 5. The cable according to claim 1 or 2, characterized in that both polymer layers of the sheath are made of a composition based on thermoplastic elastomer that does not spread combustion. 6. The cable according to claim 1 or 2, characterized in that under the outer conductor is laid longitudinally with overlapping metal-polymer tape with a metal layer up. 7. The cable according to claim 1 or 2, characterized in that it is additionally equipped with an electric shield laid over or under a layer of reinforcing threads. 8. The cable according to claim 7, characterized in that a screen wire is laid under the electric screen. 9. The cable according to claim 1 or 2, characterized in that a layer of water-blocking material, armor made of round wires and an outer protective hose made of polymer material are sequentially applied over a three-layer sheath. 10. The cable according to claim 1 or 2, characterized in that in all the gaps between the structural elements introduced polymer sealant. 11. An electric communication cable, comprising at least two cables according to claim 1, placed in a protective polymer sheath. 12. The cable according to claim 11, characterized in that at least two cables according to claim 1, located in a protective sheath, are twisted into a core. 13. The electric cable according to claim 11 or 12, characterized in that the protective polymer sheath is made of three layers, the middle of which is made of reinforcing threads, and the other two are made of a composition based on thermoplastic elastomer that does not spread combustion. 14. The cable according to claim 11 or 12, characterized in that a layer of water-blocking material, armor made of round steel wires and an outer protective hose of polymer material are sequentially applied over the protective polymer sheath. 15. The cable according to claim 11 or 12, characterized in that a polymer sealant is introduced in all the gaps between the cable structure elements.

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