RU231348U1 - POWER CABLE WITH ALUMINUM CORE - Google Patents

Abstract

The utility model relates to electrical engineering, namely to power cable designs for transmitting electric energy from converter substations to the contact network of urban electric transport. The technical result consists in ensuring the stability of the cable's electrical parameters due to resistance to moisture. The technical result is achieved in that the cable contains an aluminum conductive core twisted with a thread made of a water-blocking material. The core is insulated with tree-resistant cross-linked polyethylene 2.6 mm thick. On top of the insulation are screens made of copper tapes, between which is also applied insulation made of tree-resistant cross-linked polyethylene 2.6 mm thick. On top of the screens is a water-blocking barrier made by winding with an overlap of at least 40% in the longitudinal direction by two water-absorbing tapes. The thickness of the tapes is 0.3 mm, the surface density is not less than 100 g/ ^m2 , the absorption rate is not less than 9 mm/min, and the absorption height is not less than 12 ^mm3 /min. 1 s.p. f-ly, 1 ill.

Description

The utility model relates to the field of electrical engineering, namely to the design of power cables for transmitting electrical energy from converter substations to the contact network of urban electric transport.

A power cable for a voltage of 45-330 kV is known from the prior art, comprising one multi-wire conductive core with a nominal cross-section from 500 mm to 2500 ^mm2 , a first screen made of an electrically conductive cross-linked polyethylene composition, insulation made of cross-linked polyethylene, a second screen made of an electrically conductive cross-linked polyethylene composition, a metal screen made of copper wires wrapped with a spirally applied copper tape, a separating layer and an outer sheath, wherein an additional winding of conductive polymer tape is applied along the conductive core (patent RU 161088, H01 B 9/02, published 10.04.2016).

A power cable with cross-linked polyethylene insulation for a voltage of 1 kV is known, containing:

- conductive core - aluminum or copper single-wire or multi-wire class 1 or 2 according to GOST 22483-77;

- cable insulation - silane-crosslinked polyethylene;

- an inner shell made of low-flammability polyvinyl chloride plastic with an oxygen index of at least 40;

- protective cover - armor made of steel tapes and a protective hose made of polymer materials;

- water-blocking elements that prevent the longitudinal spread of water;

- an outer shell made of polyvinyl chloride plastic or polyvinyl chloride plastic with low fire hazard, with an oxygen index of at least 40.

Cables are made with four or five cores. Four or five-core power cables are made with cores of the same cross-section, four-core power cables are also made with one core of a smaller cross-section (Electronic catalog of the electrical engineering company "Elekom", Internet source: rttps://elekom.ru/produ1i-silovye-s-izolyatsiej-iz-sshitogo-polietilena-na-napryazhenie-lkv?ysclid=lnhve3paf6606891888, found on the Internet on 09/20/2024).

The closest analogue of the proposed technical solution is a power cable with an aluminum core, having insulation made of cross-linked polyethylene for a voltage of 1 kV AC and DC, an aluminum core with a cross-section of 800 mm ² , shielded by two screens of two copper tapes 0.2 mm thick, sealed with water-blocking tapes that help reduce tracking, with a reinforced outer sheath for transmitting electrical energy from converter substations to the contact network of urban electric transport, while the working insulation is made of cross-linked tree-resistant polyethylene 2.6 mm thick, the water-blocking tape has a thickness of 0.2 mm, and the protective hose is made of light-stabilized high-density polyethylene 3.2 mm thick (Power cable for powering contact networks of electric transport, OOO EM-kabel, Internet source: https://emcable.ru/assets/files/produkciya/silovye/el-transport/buklet-new.pdf?ysclid=lnhvbtdegb60671017, found on the Internet on 09/20/2024).

All the above-mentioned known technical solutions have a common drawback: insufficient resistance of the cable to the combined effects of electrical voltage, humidity and pollution, and reduced resistance of insulating materials to tracking and erosion damage.

The technical problem, which the proposed utility model is aimed at solving, is the development of a cable design that will ensure the reliability and stability of the electrical parameters of a power cable for transmitting electrical energy from converter substations to the contact network of urban electric transport.

The technical result achieved by implementing the proposed utility model consists of ensuring the stability of the electrical parameters of a power cable for transmitting electrical energy from converter substations to the contact network of urban electric transport.

The specified technical result is ensured by the fact that the power cable contains an aluminum core with a cross-section of 800 ^mm2 with insulation applied thereto made of tree-resistant cross-linked polyethylene with a thickness of 2.6 mm for a voltage of 1 kV alternating and direct current, a first screen made of copper tapes, a second screen made of copper tapes and a water-blocking barrier located in front of the outer sheath made of light-stabilized polyethylene, wherein the aluminum core is twisted with a thread made of water-blocking material, on top of said insulation of the aluminum core there is a first screen made of copper tapes, on top of which insulation made of said tree-resistant cross-linked polyethylene with a thickness of 2.6 mm is applied, and then a second screen made of copper tapes is located, and said water-blocking barrier, located in front of the outer sheath, is made by winding with an overlap of at least 40% in the longitudinal direction of two water-absorbing tapes with a thickness of 0.3 mm, having a surface density not less than 100 g/ ^m2 , absorption rate not less than 9 mm/min and absorption height not less than 12 ^mm3 /min.

Moreover, the thickness of each screen is 0.1 mm.

The proposed utility model is illustrated by a drawing showing the cross-section of a power cable, with the following positions designated:

1 - aluminum conductive core;

2 - thread made of water-blocking material;

3 - insulation;

4 - first screen;

5 - insulation;

6 - second screen;

7 - water-blocking barrier;

8 - outer shell.

A power cable used for transmitting electric energy from converter substations to the contact network of urban electric transport comprises an aluminum core 1 with a cross-section of 800 mm with insulation 3 applied thereto made of tree-resistant cross-linked polyethylene with a thickness of 2.6 mm for a voltage of 1 kV of alternating and direct current, a first screen made of copper tapes, a second screen made of copper tapes and a water-blocking barrier located in front of the outer sheath made of light-stabilized polyethylene. The aluminum core 1 is twisted with a thread made of water-blocking material 2. Such an embodiment of the aluminum core ensures reliable protection of the cable from moisture and reduces the risk of a short circuit in the event of cable damage. Above the said insulation 3 of the aluminum core 1, there is a first screen made of copper tapes 4, on top of which insulation 5 of the said tree-resistant cross-linked polyethylene with a thickness of 2.6 mm is applied. Then the second screen of copper tapes 6 is located, and the mentioned water-blocking barrier 7, located in front of the outer shell 8, is made by winding with an overlap of at least 40% in the longitudinal direction of two water-absorbing tapes with a thickness of 0.3 mm. The presence of a water-blocking barrier under the outer shell prevents the spread of moisture when the outer shell is damaged, and also limits the risk of cable damage. The water-absorbing tapes have a surface density of at least 100 g / m ² , an absorption rate of at least 9 mm / min and an absorption height of at least 12 mm ³ / min. The thickness of the screen is 0.1 mm, which reduces power losses in the normal operating mode of the power cable. The proposed combination of all the specified structural elements of the proposed cable design, as well as the characteristics of the surface density, speed and absorption height of the water-absorbing tapes used in the cable with a thickness of 0.3 mm, applied with an overlap of at least 40%, ensures the stability of the electrical parameters of the power cable for transmitting electrical energy from converter substations to the contact network of urban electric transport by eliminating the penetration of moisture into it.

During the operation of the cable, mechanical damage to its sheath can cause the entry and longitudinal spread of a significant amount of water into their cores, in connection with which the optimal thickness of tree-resistant cross-linked polyethylene in the proposed cable was chosen to be 2.6 mm.

The electrical parameters of the cable in the area of water penetration and the entire cable line, as a rule, go beyond the operating standards. As a result, the transmission of electrical energy from the converter substations to the contact network of urban electric transport is interrupted, which can lead to an emergency situation and significant economic losses.

The currently used means of protecting cables from the longitudinal spread of water (keeping them under excess pressure or filling their cores with hydrophobic materials) are not effective enough, and are also not technologically feasible for installation and repair work on cable lines.

More technologically advanced and promising in this regard are cables with so-called "dry" elements made of hydrophilic (water-blocking) materials. These cable designs, with an optimal choice of quantity, type, thickness, percentage of overlap during winding and arrangement of elements made of water-blocking materials, provide longitudinal moisture resistance of cables, which in turn ensures the stability of the electrical parameters of the power cable for transmitting electrical energy from converter substations to the contact network of urban electric transport without the occurrence of emergency situations leading to significant economic losses.

The main characteristics of water-blocking material elements are their surface density, absorption rate and absorption height.

An example of the implementation of the proposed cable.

The cable manufacturing technology is based on the use of industrial cable equipment and is as follows.

An aluminum core 1 with a cross-section of 800 ^mm2 is wrapped with threads made of water-blocking material 2 and twisted with them on frame lantern-type twisting machines or SZ-twisting machines.

On the aluminum core 1, twisted with a thread of water-blocking material 2, insulation 3 made of tree-resistant cross-linked polyethylene with a thickness of 2.6 mm for a voltage of 1 kV alternating and direct current is applied on the extrusion line.

The application of the first screen 4 with a thickness of 0.1 mm made of copper tapes, insulation 5 made of tree-resistant cross-linked polyethylene with a thickness of 2.6 mm, the second screen 6 with a thickness of 0.1 mm made of copper tapes and water-absorbing tapes with a thickness of 0.3 mm of the water-blocking barrier 7 is carried out on winding machines or combined with the operation of applying the outer sheath.

The outer shell 8 made of light-stabilized high-density polyethylene with a thickness of 3.2 mm is applied on the extrusion line.

The longitudinal tightness tests of these power cables were carried out using the general method in accordance with GOST 20.57.406-81 (method 216-1). A 2-meter-long power cable sample was immersed in a hydrostatic pressure tank so that one 1-meter-long end was inside the tank and the other 1-meter-long end was outside. The power cable entry unit into the tank contains a seal made of epoxy resin, which has good adhesion to the power cable sheath and does not deform when exposed to radial hydrostatic pressure. This eliminates additional compression of the cable in the power cable entry unit during testing. The test was carried out in two stages.

In accordance with the requirements of the above-mentioned GOST, the first stage of testing evaluates the design and technological reserve of the tested power cable, for which a pressure of 50% greater than the working pressure is created. In our case, the working pressure for the tested samples was 6.08 MPa (60 kgf/ ^cm2 ). During testing, the rate of increase in hydrostatic pressure was 1 MPa/min. The increased pressure of the first stage of testing was 9 MPa (90 kgf/ ^cm2 ) and the sample was maintained at this pressure for 15 minutes. Then the pressure was reduced to 0.2 MPa.

At the second stage of testing, the pressure was again increased to the working value. The holding time at this pressure, in accordance with the requirements of TU16.K99-020-2009, was 120 minutes.

After testing according to the standard, the leakage volume (volume of leaked water) through the end of the outer end of the power cable sample was estimated and the obtained value was compared with the permissible value of 100 cm ³ . The results of the longitudinal tightness tests of the studied cable designs are presented in the table.

As can be seen from the table, the parameters of the used water-absorbing tapes with a thickness of 0.3 mm, having a surface density of at least 100 g/ ^m3 , an absorption rate of at least 9 mm/min and an absorption height of at least 12 mm3 ^/ min, specified in the formula of the utility model, ensure virtually no leakage volumes. To achieve these parameters of the leakage volume, the optimal value of the overlap of two water-absorbing tapes of the barrier is also determined - at least 40%.

Thus, the combination of all the characteristics of the proposed power cable design specified in the utility model formula ensures the solution of the technical problem and the achievement of the stated technical result - stability of the electrical parameters of the power cable with an aluminum core due to resistance to moisture during operation.

Claims (2)

1. A power cable comprising an aluminium core with a cross-section of 800 ^mm2 with insulation applied thereto made of tree-resistant cross-linked polyethylene 2.6 mm thick for a voltage of 1 kV alternating and direct current, a first screen made of copper tapes, a second screen made of copper tapes and a water-blocking barrier located in front of the outer sheath made of light-stabilized polyethylene, characterized in that the aluminium core is twisted with a thread made of water-blocking material, a first screen made of copper tapes is located on top of said insulation of the aluminium core, on top of which insulation made of said tree-resistant cross-linked polyethylene 2.6 mm thick is applied, and then a second screen made of copper tapes is located, and said water-blocking barrier, located in front of the outer sheath, is made by winding with an overlap of at least 40% in the longitudinal direction of two water-absorbing tapes 0.3 mm thick, having a surface density of at least 100 g/ ^m2 , absorption rate of at least 9 mm/min and absorption height of at least 12 ^mm3 /min. 2. The cable according to item 1, characterized in that the thickness of each screen is 0.1 mm.

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