RU51782U1 - ELECTRIC COMMUNICATION CABLE - Google Patents

Abstract

An electric communication cable is proposed, including two conductive cores equipped with insulating sheaths and twisted into a pair, over which a screen is placed, a wire located under the screen and a moisture-proof sheath that is not spreading on the screen, is applied. The insulating shell of each core is made of a material containing polyethylene and polypropylene, taken in an amount of from 6% to 48% by weight of polyethylene

Description

The utility model relates to the cable industry and can be used in the construction of communication and signaling cables.

It is well known telephone station cable (type TSV), consisting of conductive wires of soft copper wire, insulated with PVC compound, twisted together in pairs or triples, which are then twisted into a core. A belt insulation made of plastic tapes and a screen made of aluminum tape with tinned wire under the screen (screen wire) and a sheath made of PVC compound are applied longitudinally or by spiral winding over the core.

The telephone station telephone cable is designed for inter-unit installation of automatic telephone exchanges with the aim of transmitting analog signals in the frequency range up to 4 kHz (I.I. Grodnev et al. “Communication Lines”, Izd. Of “Radio and Communication”, M. 1988) .

The named cable type TSV is not designed to transmit analog high-frequency signals; it lacks an individual pair screen, which is necessary for pairing after removing common elements, such as a shell, a screen, and belt insulation.

To ensure the inter-unit installation of electronic telephone exchanges, a cable of type KVSPEV was developed with core insulation made of solid polyethylene, an individual pair screen and belt insulation over it, designed to transmit digital streams at a speed of up to 2.048 Mbit / s; otherwise, its design matches the performance of a type cable TSV (“Cable products”. Volume 2. Cables, wires and communication cords. Part 2 ”, Information and technical collection, M., JSC“ VNIIKP ”).

Cable type KVSPEV has the following disadvantages:

- separately selected pairs (when wiring pairs after removing common elements, such as the shell, screen, belt insulation) do not provide requirements for non-distribution of combustion;

- the cable design is not optimized for transmitting high-frequency digital signals (it does not ensure the stability of high-frequency parameters along the cable length).

The most important parameters for transmitting high-frequency digital signals are the attenuation coefficient and transient attenuation, normalized for high-frequency communication cables and determining the design and length of the cable used for a particular communication system. Moreover, ceteris paribus structural elements and dimensions, these parameters largely depend on the uniformity of the structure along the length. The uniformity of the cable design along the length is ensured by technological factors. In particular, one of the violations of the homogeneity of the cable structure along the length is the heterogeneity (roughness) of the insulation surface. In turn, the heterogeneity of the insulation surface along the length leads to a spread of wave resistance along the length, and this entails an increase in the attenuation coefficient and a deterioration in the transfer function of the cable line.

The prototype of the claimed utility model is a communication cable high-frequency station type KVSM having modifications with one, two, four and eight pairs of P core. Moreover, a cable with more than one pair is produced by twisting single-pair cables into the core and applying a common protective sheath to the core. (Journal of Communication Technologies, 2004, Mytishchi, Moscow Region. Utility Equipment, pp. 97-99) .

The electric single-pair communication cable of the KVSM type includes two conductive conductors with a diameter of 0.4 mm, equipped with insulating sheaths of polyethylene with individual colors and twisted into a pair, on top of which an aluminum-lavsan shield is applied with a metal layer inside with a screen wire under it. A moisture-proof polyvinyl chloride shell is applied over the screen, which does not spread combustion.

However, this cable is not optimized for transmitting high-frequency digital signals, since the insulation material of the conductive pairs is heterogeneous, has a roughness, which leads to a deterioration in the transfer function of the cable line.

The technical problem solved by the proposed utility model is the creation of an electric communication cable with structural elements uniform in length, ensuring the stability of high-frequency parameters (reducing the spread of wave impedance along the line length and attenuation coefficient) and optimizing the transmission of high-frequency digital signals.

 The technical problem is solved by the fact that an electrical communication cable is proposed, including two conductive cores equipped with insulating sheaths and twisted into a pair, over which a screen is placed, a wire located under the screen and a moisture-proof sheath that is not enclosed by the flame, in which there is an insulating sheath of each of cores is made of a material containing polyethylene and polypropylene, taken in an amount of from 6% to 48% by weight of polyethylene.

The material used for insulation ensures uniformity of the cable construction along the length and eliminates the spread of wave-resistance along the length of the cable, which significantly improves the transfer function of the cable line.

A comparative test of a cable with insulation made of a material containing polyethylene with the addition of polypropylene and polyethylene without polypropylene showed that in the first version of the cable it is possible to achieve an attenuation coefficient of 20% lower on average. The use of only polypropylene or the addition of polypropylene exceeding 48% by weight of polyethylene is not permissible, as this leads to a deterioration in the cold resistance of the cable.

It is advisable when laying the cable into the ground that a single-pair cable additionally contains a layer of water-blocking material superimposed on the moisture-proof sheath, armor made of metal wires and a moisture-proof hose.

To enable the cable to be suspended on poles and communication supports with gripping-type clamps, it is desirable that the cable additionally contains a protective sheath located on top of the moisture-proof sheath and a cable placed in it parallel to a pair of conductive conductors.

The technical problem is also solved by the fact that the proposed electric communication cable, comprising at least two electric single-pair cables made according to claim 1, placed in a protective sheath.

Such a design of the cable simplifies the technology of laying several identical single-pair cables that perform the same functions, while maintaining the stability of high-frequency parameters (reducing the spread of wave resistance along the line length and attenuation coefficient).

It is advisable to ensure compact design that in the proposed multi-pair cable, at least two of the aforementioned electrical single-pair cables are twisted together into a core located in the

a protective shell made of a moisture-proof material that does not spread combustion.

For laying the cable directly into the ground, it is desirable that the multi-pair cable additionally contains a layer of water-blocking material superimposed on the protective sheath, armor made of metal wires and a moisture-proof hose.

To suspend the cable on poles and communication supports with spiral clamps of a curling type, it is advisable that the multi-pair cable additionally contains a cable and at least two of these single-pair electrical cables twisted around it into the core, while the core is placed in the said protective sheath.

It is advisable to suspend the cable on poles and supports of a gripping type, so that the multi-pair cable contains at least two of these electrical single-pair cables twisted into a core and additionally contains a cable placed in the said sheath parallel to the length of the core.

In the future, the proposed utility model is illustrated by specific examples of implementation and the accompanying drawings, in which:

figure 1 depicts a cross section of a single-pair electrical cable;

figure 2 depicts a cross section of a multi-pair electrical cable;

figure 3 depicts a cross section of an armored electric cable;

figure 4 depicts a cross-section of a single-pair cable or multi-pair cable with a cable integrated in the protective sheath;

5 depicts a cross section of a multi-pair electrical cable with a cable integrated in the core.

A single-pair cable 1 (Figure 1) consists of two tinned copper conductive cores 2, each of which is equipped with an insulating sheath 3 made of a material containing polyethylene and polypropylene, and the polypropylene content should not exceed 50% by weight of polyethylene. Insulated cores 2 are twisted together in a pair, on top of which a screen 4 is laid, with metal inward, with a screen wire 5 under the screen. A moisture-proof sheath (6) is applied to the screen 4, which does not spread combustion, and is made of plastic.

Depending on the brand of polyethylene and then a specific batch within the same brand, the volumetric content of the polypropylene additive varies from 5% to

50% in order to achieve acceptable smoothness, determined organoleptically. Polyethylene and polypropylene in this case include the necessary additives to achieve the desired properties. For example, polyethylene of grade 107-02 K in accordance with GOST 16336-78 can be used.

Technical polyethylene and polypropylene coming in granules containing antioxidants and other additives that provide the desired properties of the finished products are poured into the hopper of the extruder. Under the influence of appropriate temperatures and pressure in the extruder, the granules melt and mix evenly. A viscous mass is extruded onto a conductive core linearly flowing through the extruder head and is cooled when passing through a bath of water. The presence of polypropylene leads to a change in the fluidity of the melt, which after cooling and solidification of the mass in the form of insulation allows us to achieve stable smoothness of the surface of the insulating shell. Since the melt flow rate sharply changes from one incoming batch of polyethylene to another, it is not possible to establish a constant percentage of addition of polypropylene. In each case, the percentage of polypropylene is established empirically.

A multi-pair electrical cable 7 (FIG. 2) consists of at least two single-pair cables 1 twisted together in a core, covered by a common plastic protective sheath 8 (FIG. 2).

To ensure the possibility of laying directly into the ground, an armored cable 9 is made (Fig. 3), the core of which is a single-pair cable 1 or a multi-pair cable 7, over which a layer 10 of a release material armor made of round wires 11, applied in a twisted or braided manner , moisture-proof plastic shell 12.

For suspension on the supports of communication lines and fences are made cables with a built-in cable 13 (Fig. 4) and multi-pair cables with a built-in cable 14 (Fig. 5).

Cable 13 includes a single-pair cable 1 or the core of a multi-pair cable 7, formed from twisted at least two single-pair cables 1, a cable 15 and an additional protective sheath 16. The cable 15 is placed in the sheath 16 parallel to the core or parallel to a pair of conductive cores. Cable 14 consists of a cable 15, with a polymer insulating layer 17 and twisted around it into the core of single-pair cables 1 and a common protective sheath 18 applied over the core.

Cable manufacturing technology according to the claimed utility model includes the following operations.

Conducting cores 2 are made of copper wire "wire rod", usually with a diameter of 8 mm by drawing. Depending on the diameter of the finished conductive core, the following operations can be used: coarse and medium drawing or coarse, medium, fine drawing.

Conducting cores 2 can be tinned copper, un tinned copper, single-wire and multi-wire.

Single wire tinned 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.

For stranded cores, the same technology is used to produce wire in the required amount, which is then twisted in the required combination on cigar, frame or lamp machines.

The insulation on the Conducting cores 2 is applied by extrusion from a mixture of granules of technical polypropylene and polyethylene obtained before loading into the hopper of the extruder. Twisting of cores 2 with polyolefin insulation 3 into a pair is usually carried out on frame-type machines.

Screen 4 can be made in one of the following options:

- from alumolavsan tape;

- from alumina polyethylene tape;

- from aluminum-polyvinyl chloride tape;

- from a copper lavsan tape;

- from a copper-polyethylene tape;

- from copper-polyvinyl chloride tape;

- in the form of a braid from soft copper or tinned copper wires;

- in the form of a winding made of soft copper or tinned copper wires;

The use of screens 4 made of non-laminated metal tapes is unacceptable, since the technological integrity of the screen 4 is violated. Screening tapes can be applied in the form of spiral windings on special winding machines or devices combined with torsion machines, or longitudinally using special devices built into the extrusion line.

Screen 4 in the form of a braid is superimposed on braiding machines, and in the form of a winding - on special winding machines. In order to increase the density of the braid or winding, individual wires are collected in skeins (bundles of several wires laid in parallel) on reed machines.

Screen wire 5 in combination with a copper screen is made in the form of a soft copper wire, in combination with an aluminum screen - in the form of a tinned copper wire, it can be laid in a straight and zigzag shape, previously curved (corrugated) on a special device. In some cases, the screen wire is made flexible multi-wire. The technology for producing screen wire is the same as the technology for manufacturing a conductive core.

The plastic moisture-proof sheath 6 and 8 of single-pair cables 1 and multi-pair cables 7, respectively, can be made of both PVC compound and halogen-free compound by extrusion.

For armored cable 9, a single-pair cable 1 or multi-pair cable 7 is taken, on which a tape of release material 10 is applied by winding in a spiral on the winding machine. Also, a tape of water-blocking material can be inserted under armor 11 for reservation operations. The application of the armor 11 can be carried out in the form of a braid with galvanized steel wires or similar materials on a braiding machine or in a braid on an armoring machine.

Moisture-proof sheath 12 is applied, as a rule, from polyethylene on an extrusion line.

The cable 15 is usually bought ready-made, twisted from metal wires, glass fibers or strong synthetic threads. The polymer insulation 17 of the cable 15 can be made of any polymer material by extrusion.

The protective sheath 16 or 18 is preferably made of polyethylene by extrusion, however, other polymers can be used instead of polyethylene. In this case, for the cable 13, shown in figure 4, the sheath is superimposed on the core and the cable. In the core of the cable 14 shown in FIG. 5, the cable is laid in the core for twisting operations, the cable coming in longitudinally, and the single-pair cables are twisted around it.

To confirm the technical result, 21 samples of a single-pair electric cable (I) and an electric cable of two single-pair cables (II) with different polypropylene content in the material of the insulating shells of conductive conductors were tested. The wave impedance and attenuation coefficient were measured at a attenuation frequency of 1.024 MHz.

The measurement results are presented in the table.

Table Name of parameters Measured values (range of knowledge) The polypropylene content in the material of the insulating sheath of the conductive core (%) 6 thirty 48 Wave impedance (ohms)
cable (I) 110.7-127.3 114.9-126.1 112.2-128.4 cable (II) 110.3-128.8 114.1-126.0 111.3-129.7 Attenuation coefficient (dB / km): cable (I) 33.1-34.8 30.7-32.2 32.6-34.5 cable (II) 33.0-34.6 30.2-32.0 31.9-34.4

Measurements of the attenuation coefficient in cables with insulation of conductive conductors made of a material containing only polyethylene gave the following range of values: (33.2-42.1) dB / km at a decay frequency of 1.024 MHz with a norm of not more than 35 dB / km.

Claims (8)

1. An electric communication cable, including two conductive cores equipped with insulating sheaths and twisted into a pair, a screen, a wire located under the screen and a moisture-proof sheath that is not enclosed by the flame, which is characterized in that the insulating sheath of each core is made of a material containing polyethylene and polypropylene taken in an amount of from 6% to 48% by weight of polyethylene. 2. The cable according to claim 1, characterized in that it further comprises a layer of water-blocking material superimposed on the said moisture-proof sheath, armor made of metal wires and a moisture-proof hose. 3. The cable according to claim 1, characterized in that it further comprises a protective sheath located on top of the moisture-proof sheath, and a cable placed therein parallel to a pair of conductive cores. 4. An electric communication cable, comprising at least two electric single-pair cables made according to claim 1, in a protective sheath. 5. The cable according to claim 4, characterized in that at least two of the aforementioned electric single-pair cables are twisted together into a core placed in the said protective sheath made of a moisture-proof material that does not spread combustion. 6. The cable according to claim 5, characterized in that it further comprises a layer of water-blocking material superimposed on the said protective sheath, armor made of metal wires and a moisture-proof hose. 7. The cable according to claim 4, characterized in that it further comprises a cable and at least two of the aforementioned electric single-pair cables twisted around it into the core, the core being housed in said protective sheath. 8. The cable according to claim 4, characterized in that at least two of the aforementioned electric single-pair cables are twisted into a core and it further comprises a cable placed in said protective sheath parallel to the core.