An aerial insulated cable and its connecting device

Abstract

This invention relates to the technical field of overhead insulated conductors, and discloses an overhead insulated cable and its connecting device that facilitates wiring. At the circular cross-section of the cable, from the inside out, it includes a conductor, a composite conductor shielding layer, and an insulation layer. The composite conductor shielding layer includes a first conductor shielding layer and a second conductor shielding layer. The first conductor shielding layer wraps around the conductor, filling the uneven outer surface of the conductor into a smooth cylindrical surface. The second conductor shielding layer wraps around the first conductor shielding layer, and the conductive carbon black content in the second conductor shielding layer is higher than that in the first conductor shielding layer. In this invention, the composite conductor shielding layer includes a first conductor shielding layer and a second conductor shielding layer. The second conductor shielding layer is made of a thermoplastic base material, which facilitates the separation of the second conductor shielding layer from the insulation layer during wiring by cutting with a ring blade, thus facilitating subsequent wiring operations and shielding layer connection processing after wiring.

Description

Technical Field

[0001] This invention relates to the technical field of overhead insulated conductors, and more specifically to an overhead insulated cable and its connecting device that facilitates wiring. Background Technology

[0002] Overhead insulated conductors are used in overhead power lines with an AC rated voltage of 35 kV and below. They combine the advantages of bare conductors with the safety performance of underground cables, making them an ideal choice for urban power distribution networks. Overhead insulated conductors mainly consist of a conductive core and an insulation layer. For medium and high voltage overhead insulated conductors, a semi-conductive shielding layer is also added. The conductive core is mostly made of aluminum or steel core with aluminum stranding, and the outer insulation layer is extruded with polyvinyl chloride, polyethylene, or cross-linked polyethylene, possessing good mechanical strength, high temperature resistance, and aging resistance.

[0003] When wiring medium- and high-voltage overhead insulated lines, improper treatment of the shielding layer at the connection point can directly cause the joint to become a weak point in the line. Under long-term operation, this can lead to partial discharge, continuously eroding the insulation material, and ultimately causing insulation failure and cable breakdown.

[0004] Currently, the adhesion between the shielding layer and the outer insulator in overhead insulated conductors is too strong, and the difference in physical hardness is also very small. During wiring, the insulator and shielding layer are often cut through together during the stripping process, with the shielding layer being treated as an external insulating conductor and stripped along with it. However, a section of the shielding layer needs to be left unstripped during wiring to facilitate connecting the shielding layers of the two conductor sections together. Once the shielding layer is stripped, it becomes difficult to properly handle the shielding layer at the wiring location during subsequent wiring, easily leading to wiring quality problems. Summary of the Invention

[0005] The purpose of this invention is to provide an overhead insulated cable and its connecting device that facilitates wiring. During the wiring process, the shielding layer and the insulation layer can be easily peeled off, which facilitates the wiring operation.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following solution: On the one hand, an overhead insulated cable that is easy to connect is provided. At the circular cross-section of the cable, from the inside to the outside, it includes a conductor, a composite conductor shielding layer and an insulation layer. The composite conductor shielding layer includes a first conductor shielding layer and a second conductor shielding layer. The first conductor shielding layer is wrapped around the conductor to fill the uneven outer surface of the conductor into a smooth cylindrical surface. The second conductor shielding layer is wrapped around the first conductor shielding layer. The conductive carbon black content in the second conductor shielding layer is higher than that in the first conductor shielding layer. The second conductor shielding layer is made of a thermoplastic base material.

[0007] The composite conductor shielding layer includes a first conductor shielding layer and a second conductor shielding layer. The second conductor shielding layer is made of a thermoplastic base material, which facilitates the separation of the second conductor shielding layer from the insulation layer by cutting the ring blade during wiring.

[0008] As a preferred embodiment of the present invention, the insulating layer is further provided with a lightning protection strip, which is formed by co-extrusion of the insulating layer and the lightning protection strip is parallel to the axis of the insulating layer. Multiple lightning protection strips are evenly distributed around the insulating layer.

[0009] As a preferred embodiment of the present invention, a plurality of release knots are evenly arranged on each lightning protection strip, and each release knot includes two release angles, each of which is rounded.

[0010] As a preferred embodiment of the present invention, the first conductor shielding layer is made of cross-linked polyethylene and conductive carbon black, and the second conductor shielding layer is made of a mixture of ethylene-vinyl acetate copolymer and conductive carbon black.

[0011] As a preferred embodiment of the present invention, the lightning protection strip and the release junction are made of the same base material as the insulating layer, and conductive carbon black is also mixed into the base material of the lightning protection strip and the release junction.

[0012] As a preferred embodiment of the present invention, the conductor comprises an inner steel core and aluminum stranded wires wound around the steel core, the steel core comprising an innermost main core and stranded steel wires spirally wound around the main core.

[0013] On the other hand, a connection device for an overhead insulated cable is provided for connecting the above-mentioned overhead insulated cable, including a crimping tube and annular blades provided at both ends of the crimping tube. The inner side of the annular blades is provided with a circular hole, the inner diameter of which is smaller than the diameter of the circumferential surface of the composite conductor shielding layer, and the inner diameter of which is larger than the maximum circumscribed circle diameter of the conductor cross section.

[0014] As a preferred embodiment of the present invention, a positioning guide ring is also fixedly provided on one side of the crimping tube near the ring blade portion, and the inner diameter of the positioning guide ring is equal to the maximum circumscribed circle diameter of the cross section where the conductor is located.

[0015] As a preferred embodiment of the present invention, a limiting ring is fixedly provided at the middle position inside the pressure tube, and a through hole is provided inside the limiting ring.

[0016] As a preferred embodiment of the present invention, the connecting device further includes a heat-shrinkable insulating tube wrapped around the crimping tube, wherein connecting strips are distributed on the heat-shrinkable insulating tube, and connecting contacts are fixed at both ends of each connecting strip. The connecting contacts cooperate with the connecting strips to connect the lightning protection strips on the insulation layers of the conductors at both ends.

[0017] The beneficial effects of this invention are as follows: In this invention, the composite conductor shielding layer includes a first conductor shielding layer and a second conductor shielding layer. The second conductor shielding layer is made of a thermoplastic base material, which facilitates the separation of the second conductor shielding layer from the insulation layer by cutting the ring blade during wiring, thus facilitating subsequent wiring operations and the connection of the shielding layer after wiring. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view of the overhead insulated cable in this invention; Figure 2 This is a three-dimensional view of the overhead insulated cable in this invention; Figure 3 This is a top view of the overhead insulated cable in this invention; Figure 4 for Figure 3 Enlarged view of point A in the middle; Figure 5 This is a half-sectional view of the connecting device in this invention; Figure 6 This is a schematic diagram of the structure of the connecting device in the present invention in conjunction with the overhead insulated cable; Figure 7 This is a schematic diagram of the structure of the connecting device in the present invention after the overhead insulated cable has been connected.

[0019] Reference numerals: 1-Conductor, 101-Main core, 102-Stranded steel wire, 103-Aluminum stranded wire, 2-Composite conductor shielding layer, 201-First conductor shielding layer, 202-Second conductor shielding layer, 3-Insulation layer, 4-Lightning protection strip, 401-Release junction, 402-Release angle, 5-Crimping tube, 501-Ring blade, 502-Positioning guide ring, 503-Limiting stop ring, 504-Through hole, 6-Heat shrinkable insulating tube, 7-Connecting strip, 701-Connecting contact. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0021] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "longitudinal," "lateral," "horizontal," "inner," "outer," "front," "rear," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Example 1, Reference Figures 1 to 4 This embodiment provides an overhead insulated cable that is easy to wire. In its circular cross-section, from the inside to the outside, it includes a conductor 1, a composite conductor shielding layer 2 and an insulation layer 3. The composite conductor shielding layer 2 includes a first conductor shielding layer 201 and a second conductor shielding layer 202. The first conductor shielding layer 201 is wrapped around the conductor 1 to fill the uneven outer surface of the conductor 1 into a smooth cylindrical surface. The second conductor shielding layer 202 is wrapped around the first conductor shielding layer 201. The conductive carbon black content in the second conductor shielding layer 202 is higher than that in the first conductor shielding layer 201. After the electric field on the outer surface of the conductor 1 is homogenized for the first time by the first conductor shielding layer 201, the electric field is further homogenized by the second conductor shielding layer 202, thereby further improving the effect of the shielding layer in homogenizing the electric field.

[0024] It should be noted that the current semiconductive layer is made of cross-linked polyethylene and other base resins with added conductive carbon black and other materials, and is co-extruded with the insulating layer 3. The adhesion between the semiconductive layer and the insulating layer 3 is strong and not easy to separate. When wiring, the difficult areas to handle include the area between the insulating layer 3 and the shielding layer of conductor 1, and the area between the shielding layer of conductor 1 and conductor 1. These areas are difficult to handle and are prone to sharp protrusions if not handled properly. During power transmission, these protrusions can easily form a distorted electric field, causing the insulating layer 3 to be broken down. In this embodiment, the dielectric of the second conductor shielding layer 202 is made of thermoplastic material, which is easy to cut. During wiring, it is easily cut by the ring blade 501 on the wiring conduit. The ring blade 501 enters between the insulating layer 3 and the first conductor shielding layer 201. The ring blade 501 is induction heated, and the second conductor shielding layer 202 will remelt and cool, bonding the shielding layer to the ring blade 501.

[0025] In this embodiment, the first conductor shielding layer 201 is made of cross-linked polyethylene and conductive carbon black, and the second conductor shielding layer 202 is made of ethylene-vinyl acetate copolymer and conductive carbon black. The base material in the first conductor shielding layer 201 is a thermosetting material to ensure the shape stability of the shielding layer. The second conductor shielding layer 202 is made of thermoplastic ethylene-vinyl acetate copolymer, which can easily fit with the ring blade 501 after cutting. The second conductor shielding layer 202 is heated again, melted again after heating, and then re-solidified to form a tight connection with the ring blade 501.

[0026] In this embodiment, the insulation layer 3 is further provided with lightning protection strips 4. The lightning protection strips 4 and the insulation layer 3 are formed by co-extrusion. The lightning protection strips 4 are parallel to the axis of the insulation layer 3, and multiple lightning protection strips 4 are evenly distributed around the insulation layer 3. When struck by lightning, the lightning pulse voltage arrives, and the lightning protection strips 4 quickly equalize the voltage, rapidly dispersing the lightning on the surface of the insulation layer 3. This prevents excessively high voltage from forming in a localized area of ​​the cable during a lightning strike, reducing the probability of the cable insulation layer 3 being punctured or even the cable being broken.

[0027] Furthermore, multiple release knots 401 are evenly arranged on each lightning protection strip 4. Each release knot 401 includes two release angles 402, and each release angle 402 is rounded. Overhead insulated cables are usually subjected to lightning protection wiring. When the cable is struck by lightning, the lightning spreads rapidly along the lightning protection strip 4. The release angles 402 are provided at the positions of the release knots 401. The tip structure of the release angles 402 forms a distorted electric field. At the distorted electric field, the lightning breaks down the air and consumes some of the electrical energy. Multiple release knots 401 are set on a cable. The multiple release knots 401 further consume the electrical energy of the lightning, reduce the lightning voltage at the lightning protection wiring position, and further reduce the risk of the cable being broken.

[0028] It should be noted that the release angle 402 is rounded, making it smoother and effectively preventing excessive distorted electric field at the release angle 402 position, which could directly cause the insulation layer 3 at the release angle 402 position to be broken down. The lightning protection strip 4 and the insulation layer 3 are processed by co-extrusion molding. The lightning protection strip 4 and the release junction 401 are structures formed by adding conductive carbon black to cross-linked polyethylene. Overall, the production cost of the cable will not change much, and the production process is relatively simple. Only the extrusion structure during cable production needs to be changed. The cost of the cable is not high. Moreover, the produced overhead insulated cable can not only improve the wiring quality at the connection position, but also achieve better lightning protection effect.

[0029] Furthermore, the lightning protection strip 4 and the release junction 401 use the same base material as the insulating layer 3. The difference is that the base material used to make the lightning protection strip 4 and the release junction 401 is also mixed with conductive carbon black, which has a conductive effect. The same base material facilitates the tight bonding between the lightning protection strip 4 and the insulating layer 3. The deformation coefficient is also the same, and the degree of deformation of the two is the same when thermally expanded and contracted and bent, ensuring that the lightning protection strip 4 and the insulating layer 3 are stably bonded.

[0030] In this embodiment, the conductor 1 includes an inner steel core and an aluminum stranded wire 103 wound around the steel core. The steel core includes an innermost main core 101 and a stranded steel wire 102 spirally wound around the main core 101. The diameter of the stranded steel wire 102 is smaller than the diameter of the aluminum stranded wire 103, thereby improving the overall roundness of the aluminum stranded wire 103 after stranding.

[0031] Example 2, reference Figures 5 to 7 This embodiment further provides a connection device for overhead insulated cables, used for connecting the above-mentioned overhead insulated cables that are easy to wire. It includes a crimping tube 5 and ring blades 501 disposed at both ends of the crimping tube 5. The ring blades 501 have a circular hole on their inner side. The inner diameter of the circular hole is smaller than the diameter of the circumferential surface of the composite conductor shielding layer 2, and the inner diameter of the circular hole is larger than the maximum outer diameter of the cross section of the conductor 1. Specifically, the inner diameter of the circular hole is larger than the diameter of the circular cross section of the first conductor shielding layer 201. A positioning guide ring 502 is also fixedly disposed on the side of the crimping tube 5 near the ring blades 501. The inner diameter of the positioning guide ring 502 is equal to the maximum outer diameter of the cross section of the conductor 1.

[0032] During wiring, first cut a section from one end of the overhead insulated wire, along with the insulation layer 3 and the shielding layer of conductor 1, exposing the inner conductor 1. Then, insert conductor 1 into the positioning guide ring 502. The conductor 1 mates with the positioning ring, increasing the coaxiality of the positioning guide ring 502 and conductor 1, aligning the ring blade 501 at one end of conductor 1 with the composite conductor shielding layer 2. Then, push conductor 1 further into the positioning guide ring 502, where the ring blade 501 cuts the composite conductor shielding layer 2, causing the insulation layer 3 to be squeezed to the outside of the ring blade 501. The crimping tube 5 has a smooth conductive structure, eliminating the need for an additional shielding layer. After the composite conductor shielding layer 2 contacts the crimping tube 5, it becomes energized, effectively connecting both ends of conductor 1 and the shielding layers. Furthermore, the connection point between the composite conductor shielding layer 2 and conductor 1 has no sharp structures, ensuring a stable and distortion-free electric field during power transmission. This facilitates wiring operations and guarantees connection quality.

[0033] It should be noted that after the ring blade 501 cuts the composite conductor shielding layer 2, the ring blade 501 is induction heated. The temperature of the ring blade 501 rises, and the ring blade 501 heats the second conductor shielding layer 202 to a molten state. After the second conductor shielding layer 202 cools, it solidifies and adheres to the ring blade 501, thus completing the tight connection between the second conductor shielding layer 202 and the ring blade 501.

[0034] Advantageously, a limiting ring 503 is fixedly provided at the middle position inside the pressure tube 5. A through hole 504 is provided inside the limiting ring 503. After the limiting ring 503 contacts the end of the conductor 1, it limits the cutting depth of the ring blade 501.

[0035] Furthermore, the connecting device also includes a heat-shrinkable insulating tube 6 wrapped around the crimping tube 5. The heat-shrinkable insulating tube 6 is distributed with connecting strips 7. Each connecting strip 7 has a connecting contact 701 fixed at both ends. The connecting contact and the connecting strip 7 cooperate to connect the lightning protection strips 4 on the insulation layer 3 of the conductors at both ends. The heat-shrinkable insulating tube 6 wraps the entire conductor 1 and the ring blade 501 to prevent the connection position from being exposed, and also prevents external moisture from seeping into the cable from the connection position.

[0036] Wiring process: The composite conductor shielding layer 2 and insulation layer 3 are removed from both ends of the overhead insulated conductor, exposing a section of conductor 1. One end of the cable conductor 1 is inserted into the crimping tube 5 from one end. The ring blade 501 on the crimping tube 5 cuts the composite conductor shielding layer 2 until the conductor 1 abuts against the limiting ring 503. The other end of the cable is installed with the crimping tube 5 in the same way. Then, the crimping tube 5 is crimped by a hydraulic press to make the crimping tube 5 and the conductor 1 tightly connected, thus completing the connection between the conductors 1.

[0037] The ring blade portion 501 is induction heated, and after heating, the ring blade portion 501 heats up. After the ring blade portion 501 heats up, it melts the second conductor shielding layer 202. After cooling, the melted second conductor shielding layer 202 is tightly bonded to the ring blade portion 501, thus completing the connection between the shielding layers of the cables at both ends.

[0038] Next, heat-shrinkable insulating tube 6 is inserted into conductor 1. The position of the heat-shrinkable insulation is adjusted so that the connecting strip 7 on the heat-shrinkable insulating tube 6 is aligned with the lightning protection strip 4 on the cable insulation layer 3. The heat-shrinkable insulating tube 6 is heated. After heating, the heat-shrinkable insulating tube 6 shrinks and seals the connector. The connecting contact 701 on the heat-shrinkable insulating tube 6 contacts the lightning protection strip 4, connecting the lightning protection strips 4 on the two conductors.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Based on the technical essence of the present invention, any simple modifications, equivalent substitutions, and improvements made to the above embodiments within the spirit and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An overhead insulated cable that facilitates wiring, comprising, from the inside to the outside, a conductor (1), a composite conductor shielding layer (2), and an insulation layer (3) at the circular cross-section of the cable, characterized in that, The composite conductor shielding layer (2) includes a first conductor shielding layer (201) and a second conductor shielding layer (202); The first conductor shielding layer (201) is wrapped around the conductor (1) to fill the uneven outer surface of the conductor (1) into a smooth cylindrical surface. The second conductor shielding layer (202) is wrapped around the first conductor shielding layer (201). The conductive carbon black content in the second conductor shielding layer (202) is higher than that in the first conductor shielding layer (201). The base material in the first conductor shielding layer (201) is a thermosetting material, and the base material in the second conductor shielding layer (202) is a thermoplastic material. The insulating layer (3) is also provided with lightning protection strips (4). The lightning protection strips (4) and the insulating layer (3) are formed by co-extrusion. The lightning protection strips (4) are parallel to the axis of the insulating layer (3). Multiple lightning protection strips (4) are evenly distributed around the insulating layer (3). Multiple release knots (401) are evenly arranged on each lightning protection strip (4), each release knot (401) includes two release angles (402), and each release angle (402) is rounded.

2. The overhead insulated cable for easy wiring according to claim 1, characterized in that, The first conductor shielding layer (201) is made of cross-linked polyethylene and conductive carbon black, and the second conductor shielding layer (202) is made of ethylene-vinyl acetate copolymer and conductive carbon black.

3. An overhead insulated cable for easy wiring as described in claim 1, characterized in that, The lightning protection strip (4) and the release junction (401) use the same base material as the insulating layer (3), and conductive carbon black is also mixed into the base material of the lightning protection strip (4) and the release junction (401).

4. An overhead insulated cable for easy wiring as described in claim 1, characterized in that, The conductor (1) includes an inner steel core and an aluminum stranded wire (103) wound around the steel core. The steel core includes an innermost main core (101) and stranded steel wire (102) spirally wound around the main core (101).

5. A connection device for an overhead insulated cable, characterized in that, The connection wiring for the overhead insulated cable according to any one of claims 1-4 includes a crimping tube (5) and a ring blade (501) provided at both ends of the crimping tube (5). The ring blade (501) has a circular hole on its inner side. The inner diameter of the circular hole is smaller than the diameter of the circumferential surface of the composite conductor shielding layer (2) and the inner diameter of the circular hole is larger than the maximum outer circle diameter of the cross section of the conductor (1).

6. A connection device for an overhead insulated cable according to claim 5, characterized in that, A positioning guide ring (502) is also fixedly provided on the side of the crimping tube (5) near the ring blade (501). The inner diameter of the positioning guide ring (502) is equal to the maximum circumscribed circle diameter of the cross section where the conductor (1) is located.

7. A connection device for an overhead insulated cable according to claim 5, characterized in that, A limiting ring (503) is fixedly provided in the middle position of the pressure pipe (5), and a through hole (504) is provided in the limiting ring (503).

8. A connection device for an overhead insulated cable according to claim 5, characterized in that, The connecting device also includes a heat-shrinkable insulating tube (6) wrapped around the crimping tube (5). The heat-shrinkable insulating tube (6) is provided with connecting strips (7). Each connecting strip (7) has a connecting contact (701) fixed at both ends. The connecting contact and the connecting strip (7) work together to connect the lightning protection strips (4) on the insulation layer (3) of the conductors at both ends.

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