RU2358343C1 - Symmetrical four-pair cable - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to the field of electrical engineering and is to be utilised for design of symmetrical communication cables within a shared network or structured cable systems. Concept of the invention is as follows: the symmetrical four-pair cable consists of cores with membranous-and-porous film insulation twisted into pairs and into a general lay contained in an outer sheath of a polymer material; insulation of each core within the porous layer and the membranous layer contacting each core is perforated along the whole length within each layer at an independent pitch.

EFFECT: reduction of dielectric loss and capacitive component of intra-pair interference.

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Description

The invention relates to the field of electrical engineering and can be used in the construction of symmetric communication cables on public networks and structured cable systems.

The known design of a four-pair cable containing copper conductors in dielectric insulation, twisted in pairs with different pitch, in a common external dielectric sheath (book "Structured cable systems", authors: A.B.Semenov, S.K. Strizhakov, I.R. Sunchely, DMKzdatelstvo, M. 2002, 4th edition, p. 109, Fig. 3.4 and 3.5). The disadvantage of this design is the relatively high value of the relative dielectric constant of the insulation of the cable conductors. Depending on the category, various types of insulation of cable conductors are used: for cable conductors of category 1, polyethylene with a relative dielectric constant of 2.3 is used as insulation of conductors; for cables of category 3, a dielectric material is used for insulation of cores also with a relative permittivity of 2.3; for cables of category 5e, cellular polyethylene with a sheath is used as insulation veins - film-porous polyethylene with a relative dielectric constant of 2.0; Category 6 cables use Teflon core insulation with a relative dielectric constant of 2.0.

A known design of a four-pair cable, consisting of two fours, twisted of two pairs each, with a film-porous core insulation and an external polymer sheath (p. 106, Fig. 3.2 b of the above book). The disadvantage of this design is also the high value of the relative dielectric constant of the insulation of the cores.

The closest in technical essence is the design of a four-pair cable, described in the prospectus of Teldor, Wires and Cables, Russia Ltd. 2006, 223 p., P. 35 (website: www.teldor.com.). The cable consists of four unshielded twisted (twisted) pairs twisted together, protected by a sheath of PVC for internal stationary laying; core diameter 0.51 mm, polyolefin insulation (film-porous film insulation), outer diameter of the insulated core 0.9 mm; the outer diameter of the cable is 5.0 mm.

Given the maximum signal propagation speed equal to 0.7 of the speed of light, the relative dielectric constant of the core insulation is 2.0, which is also the main disadvantage of this cable.

The task to which this technical solution is directed is the creation of such a design of a symmetrical four-pair cable that can reduce the relative dielectric constant of the insulation of the cable cores, reduce the capacitance of the pairs and, therefore, the dielectric losses and the capacitive component of the effect between the pairs.

To solve this problem, in a four-pair cable containing veins in a film-porous film insulation, twisted in pairs and in a common twist, with an external polymer sheath, the insulation of each core in a porous layer and in a film layer in contact with the core is perforated along the entire length in each layer with an independent step.

The drawing shows the design of a symmetrical four-pair cable. It contains: cores - 1, a perforated film in contact with the cores - 2, a perforated porous layer of insulation of the cores - 3, the outer insulation film of the cores, twisted pair - 5, the outer polymer cable sheath - 6.

In this design, due to perforation in the porous layer and in the film insulation layer in contact with the core, the relative dielectric constant of the core insulation is significantly reduced due to through holes in which the relative dielectric constant is 1.0 (relative dielectric constant of air is 1). Depending on the frequency of perforation, the relative permittivity can be varied over a fairly wide range, reducing the thickness of the insulation and reducing losses in the dielectric. Since the dielectric constant of the non-perforated insulation of the cores in the proposed material is 2, taking into account the porosity of the intermediate layer of the film-porous film insulation when filling through the openings of the porous layer and the film layer in contact with the cores in a volume of 30% of the total volume of insulation of the cores, we obtain the relative dielectric constant of core insulation equal to 1.7, and when filled with perforated holes in a volume of 50%, we obtain the relative dielectric constant of the entire core insulation equal to 1 ,5. As a result, the attenuation coefficient decreases due to a decrease in losses in the core insulation, wave resistance and capacitive component of the influence between the pairs, and due to a decrease in the insulation thickness and, therefore, the distance between the wires in the pair, the circuit inductance also decreases.

Claims (1)

Symmetric four-pair cable containing conductors in a film-porous film insulation, twisted in pairs and in a general twist, with an external polymer sheath, characterized in that the insulation of each core in the porous layer of each core and in the film layer in contact with each core is perforated along the entire length in each layer with an independent step.