The cable attachment is a very important process in the cable construction. The quality problem of the cable attachment directly affects the construction quality of the entire electrical engineering construction. Therefore, during the cable construction process, we must conduct a comprehensive analysis of the various countries of the cable. The guarantee cable can work stably for a long time, which is also the main role of the cable accessory work. At present, in the cable construction process, we mainly use the high voltage to move the cable to the bottom of the cable to maintain the balance of the electric field distribution area at the middle of the cable, in order to ensure the stable operation of the cable, so as to make it reasonable Stable release voltage, improve the quality of power for people to use.
First, the outline of cable accessories
1 Characteristics of cable accessories
At present, during the cable construction in China, the cable accessories mainly use chemical synthetic materials as the insulator material of the cable terminal. This material is mainly based on the method of applying high-quality rubber insulation, and it is scientifically processed so that it originally has The good hydrophobic rubber material is further developed, and it also greatly improves its self-healing properties. When water droplets appear on the rubber material, it will automatically generate a layer of film to prevent long-term use. Causes the material to age. Therefore, we can see that the cable accessories have these characteristics: insulation properties, anti-corrosion, water resistance, and some materials also have anti-ultraviolet characteristics, so it has a long service life.
2 The role of cable accessories
In fact, the action near the cable is actually very simple, which is to play a role in connection and stability, so that the voltage from the high voltage to the bottom of the cable to a certain degree, so as to achieve a stable state, the shaft stress of its various terminal power plants And to develop certain changes to the stress, so as to achieve the continuity of the cable.
At present, in the cable construction, the cable is mainly composed of three aspects: conductor, insulation, sheath and shielding, and the cable attachment is through its own connection and the role of stability, so that the function of the cable can be continued. In order to achieve a good contact between the conductor and the reliable implementation of the insulation outer layer, thus ensuring the reliability of power supply, so that people's quality of life is not affected, so that the economy can be rapid development.
When we are conducting cable construction, there is a certain uniqueness in the manufacturing process of cable accessories and other electrical components. In addition to ensuring its own stability, we must also ensure the insulation of cable accessories to ensure that There will be no problems in the long-term use of electricity, and the superior waterproofness can also greatly increase the service life of the cable.
Second, the general provisions
1 Cable terminal and street production should be trained by skilled workers.
2 When manufacturing cable terminals and their joints, the production process flow shall be strictly observed, and the oil-filled cable shall comply with the relevant provisions of the oil service and its vacuum process.
3 The three-core power cable is located at the middle of the cable connector, and its cable armour and metal shield shall have good electrical connection and insulation from each other. At the end of the cable, the cable armor and metal shield shall be led out by the bottom line connection. And should be a reasonable grounding analysis.
4 Corresponding fire-fighting equipment shall be available at the construction site of the interior and its oil-filled cable. Indoor or tunnel construction should have appropriate temporary power supply.
5 In the cable connection, due to the variety of cable terminals and connectors, the rubber roller cable and its accessories are developed in comparison with SHA. In the process of installation, various joint types often affect each other, resulting in unreasonable connection and specification. Incomplete and other influencing factors.
Third, the installation requirements
1 If the single-core cable is shielded by copper wire, the shielded copper wire is turned back after the binding with bare copper wire and left as a bridge line.
2 For single-phase direct laying, ferromagnetic materials should not be used as a protective box. It is recommended to use glass steel or hard plastic protection boxes.
Different from the traditional cable attachment construction process, the construction technology of the prefabricated cable attachment is complicated and the workmanship and technology are difficult. Its installation procedure and process requirements are not easily grasped by the construction personnel. There are generally such problems in the construction and are the influences. The main factors for proper installation and safe operation of cable branch boxes.
When installing the cable, it is necessary to determine the length of the cable accessory through various technical means. The length of the retest is appropriate and flush to prevent the excessively long or short phase cable from generating a large thrust or pulling force, resulting in a fixed T -type cable connector. Poor contact with the outlet casing of the cable or cable distribution box to prevent leakage of the cable outlet casing due to force.
The cable fixing bracket must be installed in the cable distribution box base. The cables are fixed on the brackets at the center of the cable and the following three points are to be taken. Measures should be taken to ensure that the three prongs are directly below the terminal to ensure that cables and accessories inside the distribution box are not affected. The pull-down force can effectively avoid the occurrence of air leakage due to stress caused by the outlet box of the cable distribution box.
(3) Put the conductor connecting pipe on the core conductor of stripping long-end cable, crimp it first, remove the burr and flash, remove the metal chips, wipe the cable insulation surface, semi-conductive layer surface and conductor connecting pipe with a cleaning cloth. surface.
4 pre-joint prefabricated parts. Firstly, apply a layer of silicon grease to the insulation surface of the long-end cable, the surface of the semi-conductive layer and the inner hole of the joint preform, and then apply it on the core until the cable insulation is exposed from the other end of the preform.
5 crimp the other end of the core. The joint outer sheath tube is sheathed on the stripped short end- 4 cable, and the E shielded copper mesh is placed on each phase core respectively , and then the short end cable is inserted into the core conductor of each phase and crimped at the long end. In the connecting pipe of each phase core of the cable -9- ~~, crimping is performed to remove flashes and burrs. Clean the cable insulation surface, semiconductive layer surface, and conductor connecting pipe surface with a cleaning cloth.
6 Move the joint preform to the joint position. Apply a layer of silicone grease to the insulation surface of the short-end cable, and then pull the connector preform on the long-end cable core to the joint position. Ensure that the stress cone semi-conducting layers at the two ends of the preform are just overlapped. At the ends of the cable insulation outer semiconducting layers at both ends, the specific dimensions are specified in the installation instructions provided by the manufacturer.
7 The semiconducting self-adhesive tape is wrapped around the insulated semiconductive layer of the cable core and the prefabricated YC --conductive layer to form a continuous conical transitional surface.
8 Move the shielded copper screen to the middle of the joint and stretch it evenly to the two ends so that it is tightly attached to the surface of the joint of the preform. The ends are tied and welded to the cable shield copper tape. The shielded copper wire mesh can also be applied by winding .
9 Pinch the three-phase joints, and then tie the bridge wires (tinned and woven copper wires) to the steel strips of the cables at the two ends of the joint and the three core shield steel strips respectively, and weld them securely. Use a white or PVC tape to bind the three-phase joints and fill the three-phase gap with packing to make it as round as possible.
Fourth, the installation of attention
In the construction of cable terminations, the dimensions of the prefabricated cable attachment installation instructions must be strictly followed . The cable terminal construction requirements of different manufacturers' T -type cable connector products are slightly different and cannot be in accordance with conventional cable terminal assembly dimensions or from other manufacturers. Exploit size for construction.
During the construction process, ensure that the stripping dimensions of the copper terminations, semi-conducting layers, and insulation layers of the cable terminations are correct. Otherwise, the semi-conductive layer and the copper shielding layer of the cable are left too much or too little, and the length of the insulation part is too long or insufficient. influences.
After summarizing the above, the basic cause of damage to the cable distribution box during operation caused by the failure of the prefabricated cable accessory equipment is the construction quality of the cable head. However, the construction personnel are not familiar with the construction technology of the prefabricated cable accessories.
It can be seen that the cable attachment has a very important role in the construction of the cable. It not only controls the movement of the high voltage effectively, but also makes the voltage have a certain stability when it is used, so that people's life production has been certain. help. However, due to stringent requirements for the installation technology of cable accessories, it is necessary to strictly install the installation project, the construction requirements for its installation, to avoid a series of problems due to improper installation methods, resulting in the occurrence of safe construction.
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