Power cable joint with multi-layer insulation structure

Abstract

The utility model discloses a power cable joint with a multilayer insulation structure. The power cable joint comprises a joint assembly, an insulation sealing chamber and a cable sealing assembly. The joint assembly is arranged in the insulation sealing cabin, and two ends are respectively welded with wire cores of the two sections of power cables; cable sealing assemblies are arranged at two ends of the insulating sealing bin and are used for radially sealing an outer insulating layer of a cable; according to the connector assembly, two hook-shaped conductors are buckled with a buckling terminal and are pressed tightly through a terminal fixing bolt, so that dual mechanical and electrical connection is formed; a cover plate and a cover plate sealing ring are arranged on a lateral opening of the insulation sealing bin, and a quadruple insulation sealing system is achieved. The cable does not need encapsulating materials, is convenient to install and maintain, and is suitable for various laying environments of medium and low voltage power systems.

Description

Technical Field

[0001] This utility model relates to the field of power cable connection device technology, and in particular to a power cable connector with a multi-layer insulation structure. Background Technology

[0002] In power transmission and distribution systems, power cable joints, as key components connecting two cable segments, directly affect the safety and reliability of the entire transmission system. With the continuous expansion of power grids and increasing demands for power supply continuity, higher requirements are placed on the insulation performance, sealing capability, and mechanical stability of joints. Existing cable joints typically employ single or simple double-layer insulation structures, relying primarily on materials such as heat-shrink tubing, rubber sealing rings, or epoxy resin for insulation and sealing. However, these structures are susceptible to environmental humidity, temperature changes, and mechanical stress during long-term operation, leading to decreased insulation performance, sealing failure, and even partial discharge and breakdown faults, potentially causing power outages in severe cases. Furthermore, traditional joint structures often suffer from complex operation, unreliable connections, and inconvenient disassembly during installation and maintenance, especially in situations requiring frequent maintenance or replacement, where their limitations become more pronounced. Therefore, there is an urgent need for a power cable joint with multi-layer insulation protection, excellent sealing performance, and a robust and reliable structure to effectively improve the safe operation and service life of the joint under complex operating conditions. Utility Model Content

[0003] This invention addresses the common technical problems of insufficient sealing, unstable insulation performance, poor mechanical connection reliability, and complex on-site installation and maintenance of existing power cable joints in practical applications. It provides a power cable joint with a multi-layer insulation structure. Through a structured multi-insulation and sealing design, combined with modular assembly and a dual conductor connection mechanism, this joint achieves reliable electrical connection, excellent environmental sealing, and convenient on-site construction and maintenance capabilities without relying on external potting materials or complex processes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A power cable joint with a multi-layer insulation structure includes a joint assembly, an insulating sealing chamber, and a cable sealing assembly. The two ends of the joint assembly are electrically connected to the cable cores of two power cables to be connected, and the entire assembly is housed within the insulating sealing chamber. The insulating sealing chamber has through holes at both ends, and the cable sealing assembly is installed at each through hole. The power cable passes through the cable sealing assembly sequentially and extends into the insulating sealing chamber, with its cable core connected to the joint assembly. The outer insulation layer of the cable is sealed and insulated by the cable sealing assembly.

[0006] Furthermore, the insulating sealing chamber includes an insulating sealing chamber body, a cover plate, and a cover plate sealing ring; the insulating sealing chamber body is a hollow shell structure with an openable opening on one or both sides, which is closed by the cover plate; the cover plate sealing ring is provided between the cover plate and the insulating sealing chamber body to achieve sealing and insulation at the lateral opening; both ends of the insulating sealing chamber body are provided with through holes for passing through power cables, and the cable sealing assembly is fixedly connected to each through hole. The insulating sealing chamber body is made of high dielectric strength engineering plastic or composite insulating material, and its internal cavity size is adapted to the overall shape of the connector assembly to ensure that the connector assembly does not shake inside the chamber and maintains a minimum safe electrical clearance with the chamber wall.

[0007] Furthermore, the cable sealing assembly includes a cable insulation sealing tube and a sealing ring; one end of the cable insulation sealing tube is fixedly connected to the end through hole of the insulation sealing chamber body, and its inner wall is provided with an annular groove; the sealing ring is embedded in the annular groove; the outer insulation layer of the power cable passes through the sealing ring and enters the interior of the insulation sealing chamber, thereby achieving sealing and electrical insulation in the radial direction. The cable insulation sealing tube and the insulation sealing chamber body are fixed by threaded connection, snap connection or adhesive bonding to ensure that there is no relative displacement between the two in the axial and circumferential directions; the sealing ring is made of silicone rubber, EPDM rubber or fluororubber, and its inner diameter is slightly smaller than the outer diameter of the cable outer insulation layer, forming an interference fit, so that the cable outer insulation layer is subjected to uniform radial compression force when passing through the sealing ring, thereby forming a continuous sealing interface between the cable outer surface and the sealing ring, and blocking the path of moisture and dust to enter the interior of the chamber along the cable outer sheath.

[0008] Furthermore, the connector assembly includes two conductor snap-fit ​​terminals; one end of each conductor snap-fit ​​terminal is constructed as a hook-shaped structure, and the two hook-shaped structures interlock and connect with each other; the other end is welded to the cable core of the corresponding power cable; the two conductor snap-fit ​​terminals are located entirely inside the insulating sealed chamber. The conductor snap-fit ​​terminals are made of highly conductive copper alloy or tin-plated copper material, and the inner surface of their hook-shaped structures is a flat or slightly arc-shaped surface with a contact area not less than 1.5 times the cross-sectional area of ​​the cable core to reduce contact resistance and improve current carrying capacity; the root of the hook-shaped structure is provided with reinforcing ribs to enhance bending and tensile strength.

[0009] Furthermore, the mating contact surfaces of the two conductor-locking terminals are provided with terminal threaded holes. Each terminal contributes half of the hole segment, forming a complete internal threaded hole when the two hook-shaped ends are engaged. A terminal fixing bolt is threaded into the terminal threaded hole to axially press the two conductor-locking terminals together, enhancing the stability of the mechanical connection and the reliability of the electrical contact. The axis of the terminal threaded hole is perpendicular to the mating surface of the conductor-locking terminals and located in the central region of the hook-shaped structure. The terminal fixing bolt is made of stainless steel or brass and has an anti-loosening structure on its head. Tightening the bolt creates pre-tightening pressure on the mating surfaces of the two conductor-locking terminals, eliminating microscopic gaps and preventing increased contact resistance due to vibration or thermal expansion and contraction.

[0010] This invention achieves a quadruple insulation and sealing system through the above structure: the first layer is the outer insulation layer of the power cable itself, forming a basic insulation barrier; the second layer is a radial sealing insulation interface formed by the sealing ring and the cable insulation sealing tube, blocking the channel for external environmental media to intrude along the cable sheath; the third layer is the main insulation barrier provided by the insulation sealing chamber body, completely isolating the entire joint assembly from the external environment and withstanding the system operating voltage and possible transient overvoltages; the fourth layer is the lateral sealing insulation formed by the cover plate sealing ring between the cover plate and the chamber body, preventing moisture and dirt from seeping in from the lateral opening of the chamber body. The quadruple insulation structure is spatially independent and functionally synergistic. Even if one layer fails due to aging or damage, the remaining layers can still maintain basic insulation and sealing functions, significantly improving the long-term operational safety of the joint under harsh conditions such as humidity, salt spray, dust, or high altitude.

[0011] Specifically, the side opening edge of the insulating sealing chamber body is provided with a positioning protrusion, and the corresponding position of the cover plate is provided with a matching positioning groove. The two work together to achieve precise alignment during cover plate installation. The cover plate is fixed to the insulating sealing chamber body by screws or quick-release clips. Screw holes or clip seats are distributed at the four corners of the cover plate to ensure uniform force on the cover plate and avoid local warping that could lead to sealing failure. The cover plate sealing ring is an O-ring or rectangular cross-section elastomer with a compression rate controlled between 15% and 25%, which ensures the sealing effect while avoiding permanent deformation or rebound failure due to excessive compression.

[0012] The outer end face of the cable insulation sealing tube is provided with a tapered guide opening, which facilitates automatic centering of the power cable when it is inserted, and reduces scratch damage to the sealing ring. The inner wall of the insulation sealing chamber body is provided with support ribs or limiting steps in the joint assembly installation area to limit the axial and radial displacement of the conductor to the snap terminals, and to prevent the weld from cracking or the bolt from loosening due to the transmission of cable tension to the joint connection point.

[0013] Furthermore, the conductor is welded to the buckle terminal and the cable core using tin-lead solder or lead-free solder for fusion welding. The solder joint covers the entire connection area, and the solder fills the area fully without defects such as pores, incomplete soldering, or cold soldering. After welding, the surface of the solder joint is coated with insulating varnish or covered with heat-shrinkable insulating sleeve to form a local additional insulating layer to prevent the electric field from concentrating and causing partial discharge.

[0014] The structural design of this utility model allows the connector assembly to be installed and maintained with the side opening of the insulating sealed chamber open, without cutting the cable or using special crimping tools. It is suitable for quick on-site connections or fault replacement scenarios. During installation, the operator first strips the outer insulation layer from the ends of the two cables to be connected, exposing the cable cores of the specified length. Then, the cables are passed sequentially through the cable insulation sealing tube and sealing ring, and the cable cores are welded to the corresponding conductor interlocking terminals. Next, the hook-shaped structures of the two conductor interlocking terminals are interlocked and screwed into the terminal fixing bolts for axial tightening. Finally, the assembled connector assembly is placed into the insulating sealed chamber, the cover is closed, and locked, completing the assembly. During maintenance, only the cover needs to be opened to inspect, clean, or replace the internal connector assembly without damaging the cable body or remaking the ends.

[0015] The beneficial effects of this utility model are:

[0016] This invention constructs a multi-layered insulation system with clear physical isolation and sufficient functional redundancy through the collaborative structural design of the insulating sealing chamber, cable sealing assembly, and conductor snap-fit ​​terminals. The dual connection mechanism of hook-shaped snap-fit ​​combined with bolt tightening balances low contact resistance and high mechanical strength. The laterally openable modular chamber structure enables rapid installation and maintenance without tools or with minimal tools. This power cable connector is suitable for medium and low voltage power systems with rated voltages from 0.6 / 1kV to 8.7 / 15kV, and can be used in diverse application scenarios such as underground direct burial, tunnel laying, overhead line downleading, or temporary power supply. It solves the problems of complex processes, high costs, and non-reusability associated with traditional connectors that rely on epoxy resin potting, heat shrink tubing, or metal shells, and has a clear technical implementation path and replicable engineering application value. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0018] Figure 2 This is an exploded structural diagram of the present invention;

[0019] Figure 3 This is a schematic diagram of the external structure of this utility model.

[0020] The attached figures are labeled as follows:

[0021] 1. Insulating sealing chamber; 2. Cable insulating sealing tube; 3. Sealing ring; 4. Conductor snap-fit ​​terminal; 5. Cable core; 6. Cable outer insulation layer; 7. Terminal threaded hole; 8. Terminal fixing bolt; 9. Cover plate; 10. Cover plate sealing ring. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0023] like Figures 1 to 3 As shown, this utility model provides a power cable connector with a multi-layer insulation structure. Its overall structure includes an insulating sealing chamber 1, a cable insulating sealing tube 2, a sealing ring 3, conductor interlocking terminals 4, a cable core 5, an outer cable insulation layer 6, terminal threaded holes 7, terminal fixing bolts 8, a cover plate 9, and a cover plate sealing ring 10. The assembly process, operating principle, and technical details of this utility model in practical applications will be fully described below with reference to the accompanying drawings and reference numerals.

[0024] In the actual installation process, first prepare two sections of power cable to be connected. Each section includes a cable core 5 and an outer cable insulation layer 6. The operator must peel off the outer insulation layer from the ends of both cable sections according to standard procedures, exposing the cable core 5 at a length appropriate to the welding area of ​​the conductor-to-conductor terminal 4. This length is typically 20mm to 30mm to ensure sufficient mechanical strength and electrical conductivity after welding. Then, the cable insulation sealing tube 2 is fitted onto the end of each cable section, allowing the outer cable insulation layer 6 to pass through the inner cavity of the cable insulation sealing tube 2. One end of the cable insulation sealing tube 2 is designed with a tapered guide opening to facilitate automatic centering during cable insertion and reduce scratch damage to the subsequent sealing ring 3. The inner wall of the cable insulation sealing tube 2 is provided with an annular groove for embedding the sealing ring 3. The sealing ring 3 is made of silicone rubber material, and its inner diameter is slightly smaller than the outer diameter of the cable outer insulation layer 6, forming an interference fit. When the cable outer insulation layer 6 passes through the sealing ring 3, the sealing ring 3 is subjected to uniform radial compression, thereby forming a continuous and tight sealing interface between the cable outer surface and the sealing ring 3, effectively blocking the path of environmental media such as moisture and dust to enter the interior of the insulation sealing chamber 1 along the cable outer sheath.

[0025] After the above pretreatment, each cable core 5 is welded to one end of a conductor snap-fit ​​terminal 4. The conductor snap-fit ​​terminal 4 is made of highly conductive tin-plated copper, with one end constructed as a hook and the other end as a straight welding end. Lead-free solder is used for fusion welding, and the solder joint covers the entire connection area, ensuring full solder filling and eliminating defects such as porosity, incomplete soldering, or cold soldering. After welding, an insulating varnish is applied to the surface of the solder joint or a heat-shrinkable insulating sleeve is wrapped to form a local additional insulation layer to prevent partial discharge caused by electric field concentration. The hook-shaped structures of the two conductor snap-fit ​​terminals 4 interlock with each other, and their mating contact surfaces are planar structures with a contact area not less than 1.5 times the cross-sectional area of ​​the cable core 5 to reduce contact resistance and increase current carrying capacity. On the mating surfaces of the two conductor snap-fit ​​terminals 4, each is provided with a semi-circular terminal threaded hole 7. When the two hook-shaped structures are fully engaged, the two semi-circular holes align to form a complete internal threaded hole. Subsequently, the terminal fixing bolt 8 is screwed into the terminal threaded hole 7. The terminal fixing bolt 8 is made of stainless steel and has an anti-loosening structure on its head. After tightening, it generates pre-tightening pressure on the mating surfaces of the two conductors and the terminal 4, eliminating micro gaps and preventing increased contact resistance due to vibration or thermal expansion and contraction during equipment operation, thereby ensuring the long-term stability of the electrical connection and the firmness of the mechanical connection.

[0026] After assembling the connector assembly, it is placed entirely into the insulating sealing chamber 1. The insulating sealing chamber 1 is a hollow shell structure, injection molded from high dielectric strength engineering plastics (such as polycarbonate or epoxy resin composites). Its internal dimensions precisely match the overall shape of the connector assembly, ensuring that the conductor-to-conductor terminals 4 do not wobble within the chamber and maintain a minimum safe electrical clearance with the chamber wall. The insulating sealing chamber 1 has through holes at both ends for threaded connections of the cable insulation sealing tube 2, ensuring no relative displacement between the two in the axial and circumferential directions. Furthermore, the insulating sealing chamber 1 has an openable opening on one side, with a positioning boss at its edge for engaging with the positioning groove on the cover plate 9, achieving precise alignment during cover plate 9 installation. The cover plate 9 is secured to the insulating sealing chamber 1 by screws or quick-release clips distributed at its four corners, ensuring even force distribution and preventing localized warping that could lead to seal failure. A cover sealing ring 10 is provided between the cover plate 9 and the insulating sealing chamber 1. The sealing ring is an O-shaped cross-section elastomer made of EPDM rubber. Its compression rate is controlled between 15% and 25%, which ensures the sealing effect and avoids permanent deformation or rebound failure due to excessive compression, thereby forming a reliable sealing and insulation barrier at the lateral opening.

[0027] On the inner wall of the insulating sealed chamber 1, support ribs or limiting steps are provided corresponding to the installation area of ​​the conductor snap-fit ​​terminal 4 to limit the axial and radial displacement of the conductor snap-fit ​​terminal 4, preventing the solder joint from cracking or the terminal fixing bolt 8 from loosening due to the external cable tension transmitted to the joint connection point. The entire joint assembly is completely enclosed inside the insulating sealed chamber 1, forming an independent electrical isolation space, so that it is not affected by the external environment.

[0028] This invention achieves a quadruple insulation and sealing system through the above structure: the first layer is the cable's outer insulation layer 6, forming a basic insulation barrier; the second layer is the radial sealing insulation interface formed by the sealing ring 3 and the cable insulation sealing tube 2, blocking the intrusion of external environmental media along the cable sheath; the third layer is the main insulation barrier provided by the insulation sealing chamber 1, completely isolating the entire joint assembly from the external environment and withstanding the system operating voltage and possible transient overvoltages; the fourth layer is the lateral sealing insulation formed by the cover plate 9 and the cover plate sealing ring 10 between the cover plate 9 and the insulation sealing chamber 1, preventing moisture and dirt from seeping in from the side opening of the chamber. The quadruple insulation structure is spatially independent and functionally synergistic. Even if one layer fails due to aging or damage, the remaining layers can still maintain basic insulation and sealing functions, significantly improving the long-term operational safety of the joint under harsh conditions such as humidity, salt spray, dust, or high altitude.

[0029] In practical applications, such as underground 0.6 / 1kV low-voltage power lines, when intermediate connections between two cable sections are required, construction workers can quickly assemble the joint on-site without the need for specialized crimping tools or potting equipment, following the steps outlined above. Because the insulating sealing chamber 1 has a side-opening structure, the entire joint assembly can be welded, snapped together, and bolted while the chamber is open, greatly simplifying the on-site construction process. During later maintenance, if inspection or replacement of the joint is required, simply loosen the fixing screws or clips of the cover plate 9, open the cover plate 9, and directly observe and operate the internal joint assembly without cutting the cable or remaking the cable end, significantly improving maintenance efficiency and reducing operation and maintenance costs.

[0030] In summary, this utility model constructs a multi-layered insulation system with clear physical isolation and sufficient functional redundancy through the collaborative structural design of the insulating sealing chamber 1, the cable sealing assembly (including the cable insulating sealing tube 2 and the sealing ring 3), and the connector assembly (including the conductor snap-fit ​​terminal 4, the terminal threaded hole 7, and the terminal fixing bolt 8). The dual connection mechanism of hook-shaped snap-fit ​​and bolt tightening balances low contact resistance and high mechanical strength. The laterally openable modular chamber structure enables rapid installation and maintenance under tool-free or simple tool conditions. This power cable connector is suitable for medium and low voltage power systems with rated voltages from 0.6 / 1kV to 8.7 / 15kV, and can be used in diverse application scenarios such as underground direct burial, tunnel laying, overhead line downleading, or temporary power supply. It solves the problems of complex processes, high costs, and non-reusability associated with traditional connectors that rely on epoxy resin potting, heat shrink tubing, or metal shells, and has a clear technical implementation path and replicable engineering application value.

[0031] The technical solution of this utility model is not limited to the specific embodiments described above. All technical modifications made based on the technical solution of this utility model shall fall within the protection scope of this utility model.

Claims

1. A power cable joint having a multi-layer insulation structure, characterized by: The utility model provides an electric power cable joint device, which comprises a joint assembly, an insulation sealing bin and a cable sealing assembly, two ends of the joint assembly are connected with two ends of an electric power cable to be connected respectively, the joint assembly is located in the insulation sealing bin, the cable sealing assembly is arranged at the entrance of the insulation sealing bin, and the electric power cable is connected with the joint assembly in the insulation sealing bin through the cable sealing assembly.

2. The power cable joint with a multi-layer insulation structure according to claim 1, characterized in that: The insulation sealing bin comprises an insulation sealing bin (1), a cover plate (9) and a cover plate sealing ring (10), the insulation sealing bin (1) is of a hollow structure, one side or both sides of the insulation sealing bin (1) are open, the open side of the insulation sealing bin (1) is connected with the cover plate (9) in a closable manner, the cover plate sealing ring (10) is arranged between the cover plate (9) and the insulation sealing bin (1), and through holes are formed in two ends of the insulation sealing bin (1), cable sealing assemblies are arranged in the through holes of the two ends of the insulation sealing bin (1) respectively, and the joint assembly is located in the insulation sealing bin (1).

3. The power cable joint with a multi-layer insulation structure according to claim 2, characterized in that: The cable sealing assembly comprises a cable insulation sealing pipe (2) and a sealing ring (3), one end of the cable insulation sealing pipe (2) is fixedly connected with the insulation sealing bin (1), the cable insulation sealing pipe (2) is located at the through hole position of the two ends of the insulation sealing bin (1), an annular groove is formed in the inner wall of the cable insulation sealing pipe (2), the sealing ring (3) is located in the annular groove in the inner wall of the cable insulation sealing pipe (2), the cable outer insulation layer (6) of the electric power cable passes through the sealing ring (3) and is located in the insulation sealing bin (1), and the cable core (5) of the electric power cable is electrically connected with the joint assembly.

4. The power cable joint with a multi-layer insulation structure according to claim 3, characterized in that: The joint assembly comprises two conductor clamping terminals (4), one end of each of the two conductor clamping terminals (4) is in the form of a hook, the hooks of the two conductor clamping terminals (4) are clamped and connected, the other end of each of the two conductor clamping terminals (4) is welded with the cable core (5) of the electric power cable to be connected, and the two conductor clamping terminals (4) are located in the insulation sealing bin (1).

5. The power cable joint with a multi-layer insulation structure according to claim 4, characterized in that: The clamping contact surfaces of the two conductor clamping terminals (4) are provided with terminal threaded holes (7), the terminal threaded holes (7) are arranged on the clamping contact surfaces of the two conductor clamping terminals (4) respectively, terminal fixing bolts (8) are arranged in the terminal threaded holes (7), and the terminal fixing bolts (8) are threadedly connected with the terminal threaded holes (7).

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