Cable termination joint

Abstract

This utility model relates to the electric power industry and can be used in cable termination joints connecting high-voltage cables to electrical equipment and power lines. The technical result ensures stable compression of the stress cone and insulator under various temperature fluctuations during operation.For this purpose, the cable termination joint comprises a cable end piece, to which the cable termination is butt-joined, a stress cone, mounted on the cable termination and crimped with a solid insulator using a main spring assembly with springs operating in compression, which is located between the stress cone and the supporting part of the insulator, according to the utility model, and is also provided with an additional spring assembly located between the inner surface of the solid insulator and the outer surface of the stress cone, wherein the additional spring assembly contains springs operating in tension, and the springs of the main and additional spring assemblies are made of identical material. 1 ill.

Description

[0001] Technical field

[0002] The utility model relates to the field of electric power engineering and can be used in cable termination joints connecting high-voltage cables to electrical apparatus and power transmission lines.

[0003] Technology Level

[0004] For high-voltage cable joints, the most widely used joints are those with stress cones - elastic inserts with a conical surface located between the cable and the hardware insulator, ensuring their tight connection, as well as the ability to regulate the electric field in the joint insulation.

[0005] A design is known for a termination joint of a high-voltage power cable with cross-linked polyethylene insulation containing a solid insulator and an elastic stress cone (patent for invention RU 2064725 C1, H02G 15 / 02, published 27.07.1996, bulletin No. 21).

[0006] The disadvantage of this technical solution is the low reliability of the coupling during long-term operation due to the high probability of gas delamination between the stress cone and the solid insulator.

[0007] The closest technical solution is the design of a termination coupling (Russian Federation Patent RU 2770460 C1, published April 18, 2022, Bulletin No. 11, IPC H02G 15 / 18), which comprises a central tube made primarily of metal. A core made of a dielectric material is installed on the central tube. This is achieved by winding a dielectric material, such as paper, synthetic fabric, mesh, etc., onto the central tube, thereby forming a core, which is a cylindrical body. The core can be impregnated with an epoxy compound and then cured. The assembled core is a solid insulator made of composite materials. The lower part of the core has a conical groove. The frame is ribbed, primarily made of silicone, to provide protection from atmospheric influences and contaminants. The stress cone is installed in a conical groove and is made of silicone.The termination design also includes a spring assembly that presses the stress cone against the conical groove of the core, thereby creating the necessary force to ensure a secure mechanical connection between the cable and the termination.

[0008] The disadvantage of this technical solution is the low reliability of the specified coupling, due to the complexity of its manufacture and the possibility of partial discharges occurring between the insulator and the frame during operation, especially when operating at low temperatures.

[0009] At low temperatures, the axial dimension of the springs operating in a compressed state decreases, and, consequently, the degree of compression of the stress cone and insulator decreases, which can lead to delamination at the interface between the stress cone and the insulator. The resulting delaminations lead to partial discharges and electrical breakdown of the coupling.

[0010] Disclosure of the essence of the utility model

[0011] The objective of the utility model is to increase the reliability of the cable termination joint during operation, including during temperature fluctuations.

[0012] The technical result consists in ensuring stable compression of the stress cone and insulator under various temperature fluctuations during operation.

[0013] The technical result is achieved due to the fact that the cable termination joint, containing a cable end piece, to which the cable termination is butt-joined, a stress cone, mounted on the cable termination and crimped with a solid insulator using a main spring unit with springs operating in compression, which is located between the stress cone and the supporting part of the insulator, according to the utility model, is equipped with an additional spring unit, located between the inner surface of the solid insulator and the outer surface of the stress cone, wherein the additional spring unit contains springs operating in tension, and the springs of the main and additional spring units are made of identical material.

[0014] Brief description of drawings

[0015] The essence of this utility model is illustrated by a drawing, which shows a basic diagram of a cable termination joint.

[0016] Implementation of a utility model

[0017] The polymer-insulated cable termination joint comprises a polymer-insulated cable end-piece 1, a terminal section 2, a solid insulator 3, an elastic stress cone 4, a main spring unit 5, a supporting part of the insulator 6 and an additional spring unit 7. The cable terminal 2 is butt-joined to the cable end-piece 1, the stress cone 4 is placed on the terminal section 2 and is crimped with a solid insulator 3.

[0018] Cable end cap 1 is a conductive tip attached to the core of a polymer-insulated power cable. Cable end cap 1 is used to electrically connect the cable to the current-carrying parts of an electrical device or busbar and also provides mechanical fixation of the core.

[0019] Termination end 2 is a section of cable from which the outer sheath, armor, and shielding layers have been removed in accordance with the termination technology, leaving a section of the core's polymer insulation. The polymer insulation of termination end 2, made of cross-linked polyethylene, forms a cylindrical surface onto which stress cone 4 is placed and inserted into the internal cavity of solid insulator 3.

[0020] Solid insulator 3 is designed as an element surrounding the termination of end fitting 2 and forming the outer insulating shell of the joint. Solid insulator 3 has a conical internal cavity for accommodating stress cone 4 and cylindrical sections in the upper portion, providing mating with the cable line structure and equipment.

[0021] Stress cone 4 is made of an elastomeric material and has a through longitudinal hole coaxial with cable termination 2, forming an internal cylindrical surface adjacent to the polymer insulation of cable termination 2. This surface is designed to compensate for mechanical stress caused by temperature fluctuations. The outer surface of stress cone 4 is conical and mates with the mating internal conical surface of solid insulator 3.

[0022] The main spring unit 5 is located between the stress cone 4 and the supporting part of the insulator 6 of the solid insulator 3. The main spring unit 5 contains springs operating in compression and supporting elements in the form of a ring of rectangular cross-section, by means of which the axial force is transmitted to the stress cone 4. When assembling the coupling, the springs of the main spring unit 5 are installed with preliminary compression, ensuring that the stress cone 4 is pressed against the cable termination 2 and against the inner surface of the solid insulator 3.

[0023] The supporting part of the insulator 6 is the outer end (support part) of the solid insulator 3, through which the solid insulator 3 rests on the structure of the coupling housing and interacts with the main spring unit 5.

[0024] An additional spring unit 7 is located between the inner surface of the solid insulator 3 and the outer surface of the stress cone 4. The spring unit 7 includes tension springs placed in longitudinal sockets or channels formed in the body of the solid insulator 3.

[0025] When high voltage is applied to cable end-piece 1, an electric field is generated in the joint around the cable termination 2, solid insulator 3, and stress cone 4. Electric current flows through the cable, heating all joint components. During operation, the joint's external components can also be subject to significant ambient temperature fluctuations and mechanical stress, which, combined with heating from the current-carrying conductors, leads to significant internal thermomechanical stresses.

[0026] When the ambient temperature fluctuates, the length of the springs of the main spring unit 5, located between the outer ends of the support portion of the insulator 6 and the stress cone 4, changes. As a result, the compression ratio of the stress cone 4 and the insulator 3 also changes. When using springs that operate under compression in the main spring unit 5, the compression ratio of the stress cone 4 and the solid insulator 3 decreases significantly at low temperatures, which can cause the appearance of delamination at the boundary of the stress cone 4 and the solid insulator 3. However, the presence of springs that operate under tension in the additional spring unit 7 leads to the fact that the length of the springs is reduced, and the force acting on the stress cone 4 increases, thereby compensating for the decrease in the load from the spring unit 5. The manufacture of the springs of the main spring unit 5 and the additional spring unit 7 from an identical material, for example, steel, ensures a similar nature of their temperature change.Due to the combined action of these components, the total force acting on stress cone 4 varies to a lesser extent than in a design with only one compression component. This ensures stable compression of the mating surfaces of the stress cone and insulator under various temperature fluctuations during operation, reduces the likelihood of gas gaps and partial discharges, and thereby increases the reliability of the coupling.

Claims

A cable termination joint comprising a cable end piece to which a cable termination is butt-joined, a stress cone mounted on the cable termination and crimped with a solid insulator using a main spring assembly with compression springs located between the stress cone and the supporting portion of the insulator, characterized in that it is provided with an additional spring assembly located between the inner surface of the solid insulator and the outer surface of the stress cone, wherein the additional spring assembly contains tension springs, wherein the springs of the main and additional spring assemblies are made of identical material.

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