Electric Cable Annex (English name: Cable Accessories) is a product that connects cables and transmission lines and related power distribution devices. Generally, it refers to the intermediate connection and terminal connection of various cables in the cable line.Cable accessories are mainly based on the characteristics of the cable structure, which can restore the performance of the cable, but also ensure the extension of the cable length and the terminal connection.The reliability of high -voltage cable accessories can be judged from the aspects of electrical performance, sealing moisture -proof performance, mechanical performance and process performance.
Effect type of cable attachment
The factors of cable attachment quality are diverse, in principle, there are several aspects in principle:
Electrical performance
The quality of electrical performance is the primary principle of judging the quality of the cable accessories.The main considering the distribution of the electric field distribution of the cable attachment is reasonable, whether the measures to improve the distribution of the electric field, the electrical strength of the material, the medium loss, and the insulation of the product of the material.At the same time, it is necessary to consider the stability of electrical performance, including the chemical, physical properties and structure of cable attachment materials, such as whether the performance of the stress control material is stable, whether the stress cone is easy to deform, and the cable insulation back to the electrical field of the cable accessoriesThe influence and preventive measures of distribution, compatibility of the combination of various materials, and stability of the interface performance.In addition, the thermal properties of cable accessories should also be considered, such as the medium loss, the contact resistance of the conductor connection and its stability, the transmission release of heat, the effect of thermal expansion and contraction on the electrical and mechanical performance of each component.
Sealing performance
Sealing moisture -proof performance directly affects the electrical performance and service life of cable accessories.Whether the sealing structure of the terminal is reliable and stable.Generally speaking, there should be a metal moisture -proof shell that is matched with the intermediate joint, especially in a humid environment.
Mechanical behavior
Terminals should have enough ability to resist bending and shock -proof.The middle joint should be able to withstand some measures and prevent external damage.
Process performance
The process performance is an important condition for the design and selection of cable accessories. The installation process should be as simple as possible to facilitate on -site construction, and the construction period is short; the on -site environment requirements and the technical level of the workers are not high; the installation quality is easy to control and the quality is reliable.
Manufacturers quality assurance system
When the prefabricated cable attachment is issued, the manufacturer provides components such as rubber prefabricated parts, prefabricated stress cone, porcelain sleeve, shell, impregnation agent and other components.The quality of manufacturing quality and installation process are directly related to the final quality of the product.
Common types of cable accessories
Thermal shrinkage
Product types with a lot of medium and low -voltage cables are mainly thermal contraction attachments, prefabricated attachments, and cold contraction attachments.They have the following characteristics:
The materials used are generally composed of co-mixture composed of polyethylene, ethylene-ethyl acetate (EVA), and ethylene rubber.This type of product mainly uses stress tube to treat electrical stress concentration.That is, the parameter control method relieves the stress concentration of the electric field.The main advantages are lightweight, easy to install, good performance, and cheap prices.Stress tube is a thermal shrinkage tube of a special electrical parameter with a moderate volume resistivity (1010-1012Ωcm), a large (20-- 25), and a large (20-- 25).The stress tube is evenly distributed.This technology is generally used in the attachments of 35kV and below.Because the voltage level is high, the force tube will not work reliably.
The key technical issues in its use are:
To ensure that the electrical parameters of the force tube must reach the above standards, the value of the value can be reliable.In addition, pay attention to filling the air gap from the semi -conductive semiconductor layer of the cable insulation of the cable to eliminate the gas and achieve the purpose of reducing the local discharge.The cross -linking cable will cause a large contraction during operation due to poor internal stress treatment. Therefore, when installing an attachment, pay attention to the stress tube and the insulation shielding cover of not less than 20mm to prevent the force tube from being separated from the insulation shield during the contraction.Due to the small elasticity of thermal contraction attachment, the interface can produce air gap during thermal expansion and contraction during operation. Therefore, the sealing technology is important to prevent moisture from implantation.
Prefabrication
The materials used are generally silicon rubber or Copycoparne rubber.Mainly use the geometric structure method, that is, stress cone to deal with the problem of stress concentration.Its main advantage is that the material performance is excellent, the installation is easier and fast, and it can be installed without heating. It has good elasticity, which greatly improves the interface performance.The main forms of medium low voltage and high -voltage cables are adopted.The disadvantage is that the size of the outer diameter of the cables insulation layer is high. The usual transmission volume is 2-5mm (that is, the inner hole diameter of the cable attachment is 2 to 5mm), the over -profits are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, the cables are too small, and the cables are too small.The attachment will fail; the amount of transmission is too large, and the cable attachment is very difficult (high process requirements).Especially the problem on the intermediate connector is prominent, and the installation is not convenient, and it often becomes a fault point.The price is more expensive.The key technical issues in its use are:
The size of the attachment is matched with the specified requirements with the size of the cable to be installed.In addition, a silicon grease lubrication interface is also required to facilitate installation.
Chlorophytic
Cold shrinkable cable accessories use elastic body materials (commonly used as silicon rubber and ethyli rubber) in the factory to inject vulcanization into the factory, and then compose components of various cable accessories by expanding diameter and plastic spiral support.During the on -site installation, these pre -expanded parts are set at the end or connector of the cable after processing, and the internal supporting plastic spiral strips (supports) are drawn out of the cable accessories composed of the cable insulation.Because it relies on elastic background at room temperature, rather than heating shrinking with fire like heat shrinking cable attachments, it is commonly known as cold -shrinking cable attachments.Early cold shrinking cable terminals were only added with silicon rubber cold contraction parts. The electric field treatment still adopts a stress cone type or stress band wrap type.Cold contraction stress control tube is generally used, the voltage level ranges from 10kV to 35kV.Cold shrinking cable connectors, 1KV level uses cold contraction insulating tube to enhance insulation, 10kV level uses the internal and external semi -conductive electrical shielding layer of the connector cold contraction insulation parts.The three -core cable terminal uses a cold contraction branch.
Cold shrinkable cable accessories have the advantages of small volume, convenient operation, fast operation, no need for special tools, wide applicable range, and low product specifications.Compared with the thermal shrinking cable accessories, it does not need to be heated with fire, and it will not move or bending after installation or bending the danger of disconnected from the inner layer of the attachment like the thermal contraction cable attachmentTight).Compared with prefabricated cable attachments, although it is elastic compressor to ensure the internal interface characteristics, it does not correspond to the cross section of the cable as a prefabricated cable attachment.
It must be pointed out that before installation on the cable, the components of the prefabricated cable accessories have no tension, and the attachment of cold shrinkable cable is in a state of high tension. ThereforeThere are obvious permanent deformed or elastic stress relaxation, otherwise it will not guarantee sufficient elastic compressor after installing on the cable, so that the good interface characteristics cannot be guaranteed.

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