RU212343U1 - THREE-PHASE POWER CABLE WITH FIBER-OPTIC MODULE - Google Patents

Abstract

The utility model relates to cable technology, namely to the designs of power cables with XLPE insulation used for the transmission and distribution of electrical energy in stationary installations for a rated alternating voltage of 6, 10, 15, 20, 30, 35, 45, 66, 110 , 132, 150, 220, 275, 330 kV. A power cable containing three round metal conductors, each of which is covered with a first layer of an electrically conductive cross-linked polyethylene composition, an insulation of a cross-linked polyethylene composition, a second layer of an electrically conductive cross-linked polyethylene composition, while the conductive conductors covered with insulation and two electrically conductive layers are twisted into core, and on top of the twisted cores there is an inner sheath and an outer sheath, while two fiber-optic modules are laid between the two phases along the periphery with an attenuation coefficient of not more than 0.8 dB / km at a wavelength of (1300÷1310) nm and with a step of total twisting not more than 50 Dskr. Thanks to the fiber-optic module laid in the cable structure, it is possible to effectively carry out: cable temperature monitoring along the entire length of the cable line; calculation based on the received data of the permissible bandwidth of the cable line; determination of the distance to the break point in case of cable damage; increase efficiency in decision-making on the work of determining the places of overheating and, thus, reduce the number of cases of overheating; cable line control based on control data. The designs of the claimed utility model have been successfully tested under production conditions.

Description

The utility model relates to cable technology, namely to the designs of power cables with XLPE insulation used for the transmission and distribution of electrical energy in stationary installations for a rated alternating voltage of 6, 10, 15, 20, 30, 35, 45, 66, 110 , 132, 150, 220, 275, 330 kV.

Known power cable, which is a close analogue (prototype) of the claimed design of the power cable, this is a power cable containing three metal conductive cores, each of which is covered with a first layer of electrically conductive cross-linked polyethylene composition, insulation of cross-linked polyethylene composition, the second layer of electrically conductive cross-linked polyethylene composition , a layer of electrically conductive tape and a metal screen, while the conductive wires covered with these layers are twisted into a core around a bundle of polymeric material, and over the twisted wires there is a separating layer and an outer sheath, while the separating layer is made of polyvinyl chloride plastic compound with an oxygen index of not less than 28, and the outer shell is made of polyvinyl chloride plastic compound with an oxygen index of at least 32 (patent RU No. 148879, M. class H01B 7/295, published on 12/20/2014).

Signs of a known cable, coinciding with the signs of the claimed utility model, consist in the implementation of a three-phase cable with copper or aluminum conductive conductors, a screen over the conductor from an electrically conductive cross-linked polymer composition, insulation from a cross-linked polyethylene composition, an insulation screen from an electrically conductive cross-linked polymer composition, the presence of an outer sheath . The presence of a separating layer, a layer of electrically conductive tape, and a metal screen in particular cases of execution.

Distinctive features of the proposed utility model and the well-known cable design is the presence of a fiber-optic module located in the cable structure.

The task to be solved by the utility model is to increase the reliability of the power cable and to expand the arsenal of cables made using fiber-optic modules in the design to control various parameters during the operation of a three-phase power cable with XLPE insulation for medium and high voltage .

The technical result is achieved by the fact that a power cable containing three round metal conductive cores, each of which is covered with a first layer of electrically conductive cross-linked polyethylene composition, insulation of a cross-linked polyethylene composition, a second layer of electrically conductive cross-linked polyethylene composition, while the conductive cores are covered with insulation and two electrically conductive layers twisted into a core, and over the twisted conductors there is an inner sheath and an outer sheath, it is possible to have individual metal screens over the electrically conductive layer of a cross-linked composition of polyethylene of insulated conductive conductors or a common metal screen over the inner sheath along the conductors twisted into a core, while between the two phases along the periphery, two fiber-optic modules are laid with a total twist pitch of no more than 50 Dskr. Fiber optic modules can be single-mode or multi-mode with an attenuation coefficient of not more than 0.8 dB/km at a wavelength of (1300÷1310) nm.

Conductors can be made of copper or aluminum. A layer of electrically conductive polymer tape can be additionally applied along the conductive wires. When applying a metal screen, it is made of copper wires wrapped with copper tape, or a skein of copper wires, or aluminum (or aluminum alloy) wires wrapped with aluminum (or aluminum alloy) tape, or wrapped with aramid or polymer thread, or polymer tape. A metal screen can be applied either to each conductive core or to the twist of the cores (general screen) over the inner sheath. A separating layer can be additionally applied to the metal screen.

The outer sheath of the cable is made of polyethylene, or polyvinyl chloride, or polyvinyl chloride of low flammability, or polyvinyl chloride of low flammability in a cold-resistant version, or of polyvinyl chloride of reduced fire hazard, or of polyvinyl chloride of low flammability with low smoke emission in a cold-resistant version, or from a polymer composition that does not contain halogen-free, either from a halogen-free polymer composition in a cold-resistant version, or from a flame-retardant, halogen-free polymer composition. The outer sheath of the cable can also be made in a reinforced or two-layer version. Depending on the complexity of the cable route for which the manufactured cable is intended, the outer sheath is also made: either with a nominal thickness of 2.3 mm (for cables with an estimated diameter under the sheath up to 40 mm) to 2.7 mm (for cables with an estimated diameter under the sheath). sheath 50 mm), or in a reinforced version, i.e. with an increased thickness of the outer sheath from 2.8 mm to 3.2 mm, respectively, for cables with the same calculated cable diameter under the sheath; or with longitudinal stiffeners (110 kV and more) to prevent damage to the shell and increase mechanical strength. This design provides additional cable protection during installation and operation for laying in complex cable routes with a large number of bends. Also, depending on the task performed and the place of operation, the outer sheath of the cable can be made in a two-layer version, i.e. each layer of the outer shell is made of the same material, but different grades depending on the task. For example, both layers of the outer sheath are made of polyvinyl chloride compound, but the outer layer is made of polyvinyl chloride compound of grades that provide increased mechanical characteristics to protect the cable from external mechanical damage, and the inner layer of the outer sheath is made of grades of polyvinyl chloride compound with improved fire hazard characteristics (low flammability or reduced fire hazard), but not having sufficiently high mechanical characteristics to protect the cable from external mechanical damage. Thus, the outer sheath of the power cable, thanks to the two-layer outer sheath, reliably protects the cable from mechanical damage and protects the cable in fire-hazardous extreme conditions.

The cable can be made in a sealed version, with sealing of the conductive core and overlaying over a metal screen, over an electrically conductive insulation screen and over the inner sheath of a water-blocking tape, with a bundle in the center of the core with water-blocking threads. And an electrically conductive layer is applied over the outer shell.

Experience with power cables for medium and high voltage has shown that in order to optimize the operation of the cable in various conditions, it is necessary to ensure constant monitoring of the parameters of the cable, so that in the event of malfunctions in the power system that can lead to failure of the cable, for example, sections of increased heating, these causes were promptly eliminated. Care must be taken at all times to ensure that the maximum permissible operating temperature limits are not exceeded along the entire length of the cable line. It is proposed to use a fiber-optic module as a temperature control sensor. Fiber optic systems can work as distributed measuring sensors. Physical quantities, such as temperature or pressure, act on the fiberglass and change the properties of the light guides. The pulse propagating along the fiber-optic core interacts with the material of the light-guiding core, by changing the returned (or reflected) signal, you can get information about the temperature along the fiber-optic module and, therefore, about the temperature of the power cable, in the design of which it is included.

Such sensors, having a low weight, small size and high sensitivity, can control parameters at a distance of up to several kilometers, while they are insensitive to electromagnetic interference and are absolutely fire and explosion safe.

Fiber optic modules built into the design of the medium and high voltage power cable provide an objective control of the temperature of the cable in order to detect critical points on the route. The main advantage of such a system is its multiplexity, that is, temperature control at hundreds of points is carried out by one sensor, while a discrete system provides data transmission from only one point, and this data is considered the average of a particular area. This technology is practically independent of possible attenuation losses in the optical fiber and makes it possible to measure the temperature. For cable lines of short length (up to 10 km) and / or with a minimum number of couplings, multimode fiber is used at a wavelength of up to 1300 nm, for a longer cable route (up to 20 km) and / or with a large number of couplings, when optical monitoring loss becomes a problem, low-loss single-mode fiber is used at wavelengths above 1300 nm. It is possible to make single-sided and double-sided measurements of the optical fiber embedded in the cable. Thus, an accurate and continuous temperature measurement along the entire length of the optical fiber is ensured. Thanks to the fiber optic module built into the design of the power cable, it is possible to carry out:

cable temperature monitoring along the entire length of the cable line;

calculation based on the received data of the permissible bandwidth of the cable line;

determination of the distance to the break point in case of cable damage;

increase efficiency in decision-making on the work of determining the places of overheating and, thus, reduce the number of cases of overheating;

cable line control based on control data.

According to its purpose, a cable with a fiber optic module must have the same performance characteristics as a standard cable without a fiber optic module, i.e. the use of an optical fiber module in the design of a power cable does not impair its performance. The following cable boundary conditions are taken into account:

maximum allowable temperature of conductive wires - (90÷95)°C;

the maximum allowable temperature of the metal screen in the short circuit mode is 350°C;

the maximum allowable temperature of the optical fiber during short-term overloads - 200°C;

the maximum short circuit time of a metal circuit is 5 s.

In cable systems that use distributed temperature measurement, the fiber optic module can be located in various locations. The fiber optic module can be located next to the cable system, but outside it. The fiber optic module may be located inside the cable system, i.e. be an element of the cable design in various versions:

location under a metal screen;

location under the outer shell above the metal screen;

as an element in the construction of a metal screen;

as a structural element of a conductive conductor.

Empirically, the following option was chosen for the location of the fiber-optic module, in which the optical module is an element of the cable design:

The fiber-optic module is superimposed in the interfacial space between two current-carrying cores along the periphery, in this case, one fiber-optic module can monitor the temperature of two current-carrying cores at once, and the third - the second fiber-optic module. In principle, one fiber-optic module can also be used to control the temperature, given that a priori the temperature of all three cores at the same time should be the same, but for more accurate measurement and greater reliability (in the event of failure of one module, temperature can be measured by others) two fiber optic modules are used.

The sketch shows the location of the fiber optic module (1).

The manufacturing process of a medium and high voltage power cable with a fiber optic module is as follows:

The power cable contains three current-carrying conductors, copper or aluminum, twisted from a variety of wires and sealed, round in shape, intended for the passage of electric current.

A layer of conductive polymer tape is applied to each conductive core by winding - a fire-resistant barrier (in the case of manufacturing a fire-resistant cable), then the first layer of an electrically conductive cross-linked polyethylene composition is applied by extrusion (either on a fire-resistant barrier or directly on a conductive core), which serves for uniform distribution electric field strength at the boundary of the conductive core and the insulation layer.

On top of the first layer of electrically conductive cross-linked polyethylene composition, a layer of insulating cross-linked polyethylene composition is applied by extrusion, which serves as the main electrical insulating element and withstands the action of an electric field.

On top of the insulating layer, a second layer of electrically conductive cross-linked polyethylene composition is applied by extrusion, which serves to evenly distribute the tension between the insulation and the metal screen.

On top of the second layer of electrically conductive cross-linked polyethylene composition, a layer of electrically conductive paper tape or electrically conductive polymeric tape, or electrically conductive non-woven fabric, or electrically conductive water-blocking tape is applied, which serves as protection against mechanical damage to the second electrically conductive screen, and also serves to equalize the electric field in the cable.

A metal screen (if any) is applied over the winding from the electrically conductive tape. The main purpose of the metal screen is the uniform distribution of the zero potential over the surface of the cable insulation and the transmission of short circuit currents. The metal screen is made of metal wires twisted in one direction, on top of which a metal tape (or a skein of metal wires) is applied by winding to ensure electrical contact, while the wires and tape can be made of copper or aluminum or aluminum alloy, and the winding can be made of aramid threads, or polymer threads, or polymer tapes. A metal screen can be applied either along each conductive core, or by twisting the cores along the inner sheath of the cable.

Insulated and shielded conductors are twisted into a core around a bundle of polymer material. Then, on the shielding lines, a fiber-optic module is superimposed into the interfacial space between two current-carrying conductors with a twist.

On top of the core of twisted conductors, an inner sheath is applied by extrusion to fill the interfacial space (to give the cable an almost round shape) and a metal screen (if any). A winding of water-blocking, electrically conductive tapes or polymer linen or fiberglass tapes is applied over the inner sheath.

It is allowed to apply a separating layer in the form of a winding over the metal screen by the winding method, which is necessary to prevent leakage of the sheath material between the screen wires during the manufacturing process. In the case of manufacturing a cable with increased requirements for protection against mechanical damage, an armor pad and tape, wire or combined armor are applied over the inner sheath.

Then the outer shell is applied.

The power cable can be made in version "g" and contain a layer of electrically conductive water-blocking tape over the second electrically conductive screen and over the metal screen, and contain a water-blocking tape over the separating layer, which makes it possible to additionally protect the cable from the spread of moisture. The power cable can be made in the “gzh” version and, in addition to the design in the “g” version, contain a sealed conductive core by introducing water-blocking threads in the process of twisting, and water-blocking threads in the central bundle of twisting of the conductive cores.

The design of the claimed utility model has been successfully tested under production conditions.

Claims (16)

1. A power cable containing three round metal conductive cores, each of which is covered with a first layer of an electrically conductive cross-linked polyethylene composition, an insulation of a cross-linked polyethylene composition, a second layer of an electrically conductive cross-linked polyethylene composition, while the conductive cores are covered with insulation and two electrically conductive layers, twisted into a core, and on top of the twisted cores there is an inner sheath and an outer sheath, characterized in that two fiber-optic modules are laid between the two phases along the periphery with an attenuation coefficient of not more than 0.8 dB / km at a wavelength of (1300 ÷ 1310) nm and with a pitch of total twist not more than 50 Dckp. 2. The cable according to claim 1, characterized in that the fiber-optic module is made single-mode or multi-mode. 3. Cable according to claim 1, characterized in that the conductors are made of copper or aluminum. 4. The cable according to claim 1, characterized in that a layer of electrically conductive polymer tape is additionally applied over the conductive cores by winding. 5. The cable according to claim 1, characterized in that a layer of electrically conductive tape made of electrically conductive paper, or an electrically conductive polymeric tape, or a non-woven electrically conductive fabric, or an electrically conductive water blocking tape, is applied over the electrically conductive insulation layer. 6. Cable according to claim 5, characterized in that a metal screen made of copper wires, or aluminum wires, or aluminum alloy wires is applied over the winding along the electrically conductive layer of insulated conductive wires. 7. The cable according to claim 6, characterized in that the metal screen is wrapped with a copper tape, or a skein of copper wires, or a skein of aluminum wires or aluminum alloy wires, wrapped with an aluminum tape, or an aluminum alloy tape, or an aramid thread, or polymer thread, or polymer tape. 8. The cable according to claim 1, characterized in that the inner sheath is pressed over the twisting of the conductive cores with the interfacial space filled with materials compatible with the materials of the insulation and the outer sheath, and a winding of water-blocking, electrically conductive tapes, or polymer flax is applied over the inner sheath, or fiberglass tape. 9. Cable according to claim 1, characterized in that a metal screen is applied over the inner sheath. 10. The cable according to claim 9, characterized in that a separating layer made of an electrically conductive creped tape, or an electrically conductive cable paper, or an electrically conductive polymeric tape, or an electrically conductive tape of a non-woven fabric, or an electrically conductive water-blocking tape, or an electrically conductive glass tape . 11. The cable according to claim 1, characterized in that the bundle in the center of the core is made of rubber, or polymer twisted tapes, or water-blocking tapes. 12. The cable according to claim 1, characterized in that an armor cushion and tape, or wire, or combined armor of wires and tapes are applied over the inner sheath. 13. Cable according to claim 1, characterized in that the outer sheath of the cable is made of polyethylene, or polyvinyl chloride, or low flammability polyvinyl chloride, or low flammability polyvinyl chloride in a cold-resistant design, or low fire hazard polyvinyl chloride, or low fire hazard polyvinyl chloride with low low smoke emission PVC or PVC with low smoke emission in the cold version, or in the halogen-free polymer composition or in the halogen-free polymer composition in the cold version. 14. Cable according to claim 1, characterized in that the outer sheath of the cable is made in a reinforced or two-layer version. 15. Cable according to claim 1, characterized in that the conductive cores are sealed. 16. Cable according to claim 1, characterized in that an electrically conductive layer is applied over the outer sheath.

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