Molded wire stranded copper conductor cross-linked polyethylene insulated medium-voltage power cable

Abstract

The utility model provides a molded line stranded copper conductor cross-linked polyethylene insulated medium voltage power cable, including cable core, shielding layer, composite fire retardant layer and oversheath, the composite fire retardant layer includes second fire retardant tape and expansion layer carrier tape that are distributed from inside to outside in order, the second fire retardant tape is lapped outside the shielding layer along the first direction, the expansion layer carrier tape is lapped outside the shielding layer along the second direction, and the expansion layer carrier tape is lapped outside the shielding layer along the second direction. The expansion layer carrier tape wraps the outer side of the second fire-retardant tape in the second direction, a second fire-retardant expansion layer adheres to the inner layer of the expansion layer carrier tape, a plurality of broken grooves distributed in a matrix mode are formed in the expansion layer carrier tape, scales are formed in the positions, corresponding to the broken grooves, of the expansion layer carrier tape, and the second fire-retardant expansion layer adheres to the inner layer of the expansion layer carrier tape. The second fire-retardant expansion layer on the inner layer can turn the scales outwards in the radial direction in the expansion state, the thickness of the fire-retardant barrier formed by the second fire-retardant expansion layer on the outer side of the shielding layer is larger, and therefore the temperature-resistant duration of the fire-retardant barrier is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of electric wires and cables, in particular to a medium-voltage power cable with a stranded copper conductor and cross-linked polyethylene insulation. Background Art

[0002] Twisted wire medium-voltage power cables, with their compact conductor design with a high fill factor, excellent electrical transmission performance and mechanical stability, are widely used in medium-voltage power systems that require efficient, stable and reliable power transmission. As an important part of the power system, medium-voltage power cables carry the task of transmitting large-capacity electric energy. Once a cable fails, such as a short circuit or overload, it may cause a fire accident and cause significant losses to the power system. Therefore, medium-voltage power cables need to have good fire-resistant properties to effectively prevent the occurrence of fire accidents.

[0003] At present, the fire prevention measures on medium-voltage power cables are generally fire-retardant coatings and fire-retardant tapes on the surface of the cables. The fire-retardant coating can form a protective film at high temperatures to isolate oxygen and heat, thereby slowing down the burning rate of the cable. The fire-retardant tape will rapidly expand to form a carbonized body when exposed to flames, preventing the burning of the cable. The fire-retardant ability of the fire-retardant isolation layer formed by the fire-retardant coating and the fire-retardant tape is often affected by its thickness. Generally, the thicker the thickness, the longer the fire-retardant time. Therefore, increasing the thickness of the fire-retardant isolation layer during fire can improve the overall fire-retardant ability of the cable. Utility Model Content

[0004] The utility model provides a medium voltage power cable with a stranded copper conductor and cross-linked polyethylene insulation, comprising:

[0005] The cable core comprises a twisted core and a filling rope, and the core and the filling rope are wrapped by a wrapping layer to form a cable core with a circular cross section;

[0006] A shielding layer, braided and wrapped around the outer side of the wrapping layer;

[0007] A composite fire barrier layer wrapped around the outer side of the shielding layer;

[0008] An outer sheath, extruded and coated on the outside of the composite fire barrier layer;

[0009] Among them, the composite fire barrier layer includes a second fire barrier tape and an expansion layer carrier tape distributed in sequence from the inside to the outside, the second fire barrier tape is wrapped around the outside of the shielding layer along the first direction, and the expansion layer carrier tape is wrapped around the outside of the second fire barrier tape along the second direction. The inner layer of the expansion layer carrier tape is adhered with a second fire barrier expansion layer, and a number of broken grooves distributed in a matrix are opened on the expansion layer carrier tape. The expansion layer carrier tape forms scales corresponding to the broken grooves, so that the second fire barrier expansion layer of the inner layer can flip the scales radially outward in the expanded state.

[0010] Preferably, the breaking groove can be configured as a "C" shape, a "匚" shape, or a "V" shape, so that the scale part is integrally connected to the expansion layer carrier tape.

[0011] Preferably, the thickness of the second fireproof expansion layer on the scale is greater than the thickness of the second fireproof expansion layer on the expansion layer carrier tape.

[0012] Preferably, both the second fireproof tape and the expansion layer carrier tape include mica tapes, and the second fireproof expansion layer includes a fireproof expansion adhesive layer.

[0013] Preferably, the wire core includes a plurality of mutually stranded wires and an insulating layer extruded and coated on the outer side of the wires.

[0014] Preferably, the filling rope includes a rope core and a first fireproof tape wound around the outer side of the rope core. The rope core includes a polyethylene or polyvinyl chloride strip, and the first fireproof tape includes a flame retardant foam layer.

[0015] Preferably, a first fireproof expansion layer is adhered to the inner side surface of the first fireproof tape. The first fireproof tape is provided with a plurality of equally spaced missing grooves along the axial direction of the rope core, so that the first fireproof tape between any two adjacent missing grooves can be turned outwards in the radial direction when the inner first fireproof expansion layer is in an expanded state.

[0016] Preferably, the diameter ratio of the filling rope to the rope core is 2 to 5.

[0017] Preferably, the first fireproof expansion layer includes a fireproof expansion adhesive layer, and the coating thickness of the first fireproof expansion layer gradually decreases along the direction close to the rope core.

[0018] Preferably, the distance between any two adjacent missing grooves is set to 20 cm to 50 cm.

[0019] Compared with the prior art, the advantages of the present utility model are as follows:

[0020] In the present utility model, a composite fireproof layer is provided on the inner side of the outer sheath. The composite fireproof layer includes a second fireproof tape and an expansion layer carrier tape distributed in sequence from the inside to the outside. The inner layer of the expansion layer carrier tape is adhered with a second fireproof expansion layer, and the surface of the expansion layer carrier tape is provided with scales. The inner second fireproof expansion layer can turn the scales outwards in the radial direction when in an expanded state, so that the thickness of the fireproof barrier formed by the second fireproof expansion layer outside the shielding layer is thicker, thereby improving the temperature resistance duration of the fireproof barrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of the three-dimensional hierarchical structure of a medium-voltage power cable with a stranded copper conductor and cross-linked polyethylene insulation shown in an embodiment of the present utility model;

[0023] Figure 2 This is a schematic cross-sectional structural diagram of a medium-voltage power cable with a stranded copper conductor and cross-linked polyethylene insulation, as shown in an embodiment of the present utility model;

[0024] Figure 3 This is a schematic diagram of the hierarchical structure of a side view of a medium-voltage power cable with a stranded copper conductor and cross-linked polyethylene insulation, as shown in an embodiment of the present utility model;

[0025] Figure 4 This is a schematic structural diagram of an embodiment of the present invention in which the filling rope is unfolded;

[0026] Figure 5 This is a schematic diagram of a partial disassembled structure of the composite fire barrier layer shown in an embodiment of the present utility model;

[0027] 10. Wire core; 11. Conductor; 12. Insulation layer; 20. Filling rope; 21. Rope core; 22. First fire-blocking tape; 221. Slot; 23. First fire-blocking expansion layer; 30. Wrapping layer; 40. Shielding layer; 50. Composite fire-blocking layer; 51. Second fire-blocking tape; 52. Second fire-blocking expansion layer; 53. Expansion layer carrier tape; 531. Scale; 60. Outer sheath. DETAILED DESCRIPTION

[0028] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0029] like Figure 1-Figure 5 As shown, the utility model provides a wire-stranded copper conductor cross-linked polyethylene insulated medium-voltage power cable, which aims to increase the thickness of the fire-retardant isolation layer in the event of a fire and improve the overall fire-retardant ability of the cable. The cable mainly includes a cable core, a shielding layer 40, a composite fire-retardant layer 50 and an outer sheath 60.

[0030] The cable core includes a twisted core 10 and a filling rope 20 , and the core 10 and the filling rope 20 are wrapped by a wrapping layer 30 to form a cable core with a circular cross-section.

[0031] Furthermore, the core 10 includes a plurality of conductors 11 twisted together in a regular twisting manner of 1+6+12+18 and an insulating layer 12 extruded and coated on the outside of the conductors 11. The conductors 11 are made of annealed oxygen-free fine copper wire, which can improve the overall flexibility of the conductors 11. The insulating layer 12 is made of three-layer co-extruded cross-linked polyethylene (XLPE) to improve the insulation strength of the cable and ensure that the cable can operate safely and stably in high voltage and high electric field environments.

[0032] Furthermore, the filling rope 20 includes a rope core 21 and a first fire barrier strip 22 wound around the outside of the rope core 21, wherein the rope core 21 can be made of polyethylene or polyvinyl chloride strips, so that the filling rope 20 has a certain support in the center to prevent the filling rope 20 from being excessively compressed and deformed, thereby maintaining the roundness of the cable core. The first fire barrier strip 22 can be made of a flame retardant foam layer to enhance the overall flexibility of the cable through the compressibility of the flame retardant foam.

[0033] like Figure 4 As shown, a first fire-blocking expansion layer 23 is adhered to the inner side of the first fire-blocking belt 22, and the first fire-blocking belt 22 is provided with a plurality of equally distributed grooves 221 along the axial direction of the rope core 21, so that the inner first fire-blocking expansion layer 23 can flip the first fire-blocking belt 22 between any two adjacent grooves 221 radially outward in the expanded state.

[0034] In some embodiments, the first fire-retardant expansion layer 23 adopts a fire-retardant expansion adhesive layer. The fire-retardant expansion adhesive layer can use emulsion resin as the base material, and an expansion flame retardant system including an acid source, a carbon forming agent and a foaming agent, as well as fillers and additives are added thereto to form a flame-retardant expansion adhesive layer, so that it can expand rapidly and form a flame-retardant barrier when encountering high temperature or flame.

[0035] Preferably, the coating thickness of the first fire-retardant expansion layer 23 gradually decreases in the direction approaching the rope core 21, and the spacing between any two adjacent grooves 221 is set to 20cm to 50cm. In this way, when the flame burns to the filling rope 20 and the outer shielding layer 40 is damaged, the first fire-retardant expansion layer 23 will expand and squeeze the first fire-retardant belt 22 outward, so that the high-temperature part of the first fire-retardant belt 22 expands outward under the squeezing of the inner first fire-retardant expansion layer 23, forming a thicker fire barrier.

[0036] Optionally, the ratio of the diameter of the filling rope 20 to the diameter of the rope core 21 is 2 to 5, so that the filling rope 20 has both flexibility and support, and can make the cable as a whole more flexible while keeping the cable core round.

[0037] Further, the wrapping layer 30 can be made of mica tape or fiberglass tape, and is wrapped around the outer sides of the core 10 and the filling rope 20 to make the cable core more round. The shielding layer 40 is braided and coated around the outer side of the wrapping layer 30. The shielding layer 40 can be made of fine copper wires braided into a mesh structure and coated around the outer side of the wrapping layer 30. The shielding layer 40 plays an important role in aspects such as electromagnetic shielding, grounding protection, and improving the electric field distribution.

[0038] Further, the composite fireproof layer 50 is wrapped around the outer side of the shielding layer 40, and the outer sheath 60 is extruded and coated around the outer side of the composite fireproof layer 50.

[0039] As Figure 5 shown, the composite fireproof layer 50 includes a second fireproof tape 51 and an expansion layer carrier tape 53 which are distributed in sequence from the inside to the outside. The second fireproof tape 51 is wrapped around the outer side of the shielding layer 40 along the first direction, and the expansion layer carrier tape 53 is wrapped around the outer side of the second fireproof tape 51 along the second direction.

[0040] Among them, the inner layer of the expansion layer carrier tape 53 is adhered with a second fireproof expansion layer 52, and a plurality of break grooves are formed in the expansion layer carrier tape 53 in a matrix distribution. Scales 531 are formed at the positions corresponding to the break grooves of the expansion layer carrier tape 53, so that the second fireproof expansion layer 52 on the inner layer can turn the scales 531 outwards along the radial direction in the expanded state.

[0041] In some embodiments, both the second fireproof tape 51 and the expansion layer carrier tape 53 can be made of mica tape. The second fireproof expansion layer 52 includes a fireproof expansion adhesive layer. The fireproof expansion adhesive layer can use emulsion resin as the base material, and an expansion flame retardant system including an acid source, a charring agent, and a foaming agent, as well as fillers and additives are added to it to jointly form a flame retardant expansion adhesive layer, so that it can expand rapidly and form a fireproof barrier when encountering high temperature or flame.

[0042] In an optional embodiment, the break grooves can be configured as "C" shape, "匚" shape, "V" shape, so that part of the scales 531 is integrally connected with the expansion layer carrier tape 53, the scales 531 area is turned over by the fireproof expansion adhesive layer expanded inside, and part of the scales 53 are connected with the expansion layer carrier tape 53 to avoid the disorderly expansion of the fireproof expansion adhesive layer.

[0043] Preferably, the thickness of the second fireproof expansion layer 52 on the scales 531 is greater than the thickness of the second fireproof expansion layer 52 on the expansion layer carrier tape 53. In this way, when the second fireproof expansion layer 52 on the inner side of the scales 531 encounters high temperature or flame, it can expand outwards and turn part of the scales 531 outwards, so that the thickness of the fireproof barrier formed by the second fireproof expansion layer 52 outside the shielding layer 40 is thicker, thereby improving the temperature resistance duration of the fireproof barrier. <000009�>

[0044] In combination with the above embodiments, a composite fire-blocking layer 50 is provided on the inner side of the outer sheath 60. The composite fire-blocking layer 50 includes a second fire-blocking tape 51 and an expansion layer carrier tape 53 distributed from the inside to the outside. The inner layer of the expansion layer carrier tape 53 is adhered with a second fire-blocking expansion layer 52, and the surface of the expansion layer carrier tape 53 is provided with scales 531. The inner second fire-blocking expansion layer 52 can flip the scales 531 radially outward in the expanded state, so that the fire barrier formed by the second fire-blocking expansion layer 52 on the outside of the shielding layer 40 is thicker, thereby improving the temperature resistance time of the fire barrier.

[0045] While the present invention has been described above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A medium voltage power cable with stranded copper conductor and cross-linked polyethylene insulation, characterized in that: Comprising: A cable core, including a stranded conductor core (10) and a filling rope (20), and the conductor core (10) and the filling rope (20) are wrapped by a wrapping layer (30) to form a cable core with a circular cross-section; A shielding layer (40), braided and coated on the outer side of the wrapping layer (30); A composite fire-resistant layer (50), wrapped on the outer side of the shielding layer (40); An outer sheath (60), extruded and coated on the outer side of the composite fire-resistant layer (50); Wherein, the composite fire-resistant layer (50) includes a second fire-resistant tape (51) and an expansion layer carrier tape (53) distributed in sequence from inside to outside. The second fire-resistant tape (51) is wrapped around the outer side of the shielding layer (40) along a first direction, the expansion layer carrier tape (53) is wrapped around the outer side of the second fire-resistant tape (51) along a second direction, a second fire-resistant expansion layer (52) is adhered to the inner layer of the expansion layer carrier tape (53), and a plurality of break grooves are formed in the expansion layer carrier tape (53) in a matrix distribution. Scales (531) are formed at positions corresponding to the break grooves of the expansion layer carrier tape (53), so that the second fire-resistant expansion layer (52) on the inner layer can turn the scales (531) outwards along the radial direction in an expanded state.

2. The cross-linked polyethylene insulated medium voltage power cable with stranded copper conductor according to claim 1, characterized in that: The break grooves can be configured as "C" shape, "匚" shape, "V" shape, so that the scales (531) are partially integrally connected with the expansion layer carrier tape (53).

3. The shaped wire stranded copper conductor cross-linked polyethylene insulated medium voltage power cable according to claim 1, characterized in that: The thickness of the second fire-resistant expansion layer (52) on the scales (531) is greater than the thickness of the second fire-resistant expansion layer (52) on the expansion layer carrier tape (53).

4. The cross-linked polyethylene insulated medium voltage power cable with stranded copper conductor according to claim 1, characterized in that: Both the second fire-resistant tape (51) and the expansion layer carrier tape (53) include mica tapes, and the second fire-resistant expansion layer (52) includes a fire-resistant expansion glue layer.

5. The cross-linked polyethylene insulated medium voltage power cable with stranded copper conductor according to claim 1, characterized in that: The conductor core (10) includes a plurality of mutually stranded conductors (11) and an insulating layer (12) extruded and coated on the outer side of the conductors (11).

6. The shaped wire stranded copper conductor cross-linked polyethylene insulated medium voltage power cable according to claim 1, characterized in that: The filling rope (20) includes a rope core (21) and a first fire-resistant tape (22) wound around the outer side of the rope core (21). The rope core (21) includes a polyethylene or polyvinyl chloride strip, and the first fire-resistant tape (22) includes a flame-retardant foam layer.

7. The shaped wire stranded copper conductor cross-linked polyethylene insulated medium voltage power cable according to claim 6, characterized in that: A first fire-resistant expansion layer (23) is adhered to the inner side surface of the first fire-resistant tape (22). A plurality of equally spaced slots (221) are provided in the first fire-resistant tape (22) along the axial direction of the rope core (21), so that the first fire-resistant expansion layer (23) on the inner layer can turn the first fire-resistant tape (22) between any two adjacent slots (221) outwards along the radial direction in an expanded state.

8. The shaped wire stranded copper conductor cross-linked polyethylene insulated medium voltage power cable according to claim 7, characterized in that: The diameter ratio of the filling rope (20) to the diameter of the rope core (21) is 2 to 5.

9. The shaped-wire stranded copper conductor cross-linked polyethylene insulated medium-voltage power cable according to claim 7, characterized in that: The first fire-resistant expansion layer (23) includes a fire-resistant expansion glue layer, and the coating thickness of the first fire-resistant expansion layer (23) gradually decreases along the direction close to the rope core (21).

10. The shaped wire stranded copper conductor cross-linked polyethylene insulated medium voltage power cable according to claim 7, characterized in that: The spacing between any two adjacent slots (221) is set to 20 cm to 50 cm.

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