Introduction to basic knowledge of power cord

1. Copper and aluminum single wire drawing of power line
The copper and aluminum rods commonly used for power lines can be reduced in cross section, added in length and improved in strength by using a wire drawing machine through one or several die holes of the drawing die at normal temperature. Wire drawing is the first process of all wire and cable companies, and the primary process parameter of wire drawing is the die matching technology.
2. Annealing of single wire of power line
When the copper and aluminum monofilament is heated to a certain temperature, it can improve the tenacity of the monofilament and reduce the strength of the monofilament by recrystallization to meet the requirements of wires and cables on the conductor core. The key of annealing process is to eliminate the oxidation of copper wire
3. Twisting of power line conductor
In order to improve the flexibility of the power line and facilitate the laying of the device, the conductive wire core is formed by taking a plurality of single wires. According to the stranding mode of conductor core, it can be divided into regular stranding and irregular stranding. Irregular stranding can also be divided into bundle stranding, concentric stranding and extraordinary stranding. In order to reduce the occupied area of the conductor and the geometric size of the power cord, the compression method is also used on the stranded conductor, so that the popular circle can be changed into semicircle, fan, tile and compact circle. This kind of conductor is mainly used in power lines.
4. Power line insulation extrusion
Extruded solid insulation layer is mainly used for plastic power lines, and the main technical requirements for plastic insulation extrusion are as follows:
4.1. Bias: The bias value of the extruded insulation thickness is the main indicator of the degree of extrusion process. Most product structure dimensions and their bias values have clear rules in the specification.
4.2. Lubricity: The extruded insulating layer shall be lubricated on the surface, and shall not present bad quality problems such as rough appearance, burning and impurities
4.3. Density: The cross section of the extruded insulating layer shall be dense and robust, with no pinholes visible to the naked eye and no bubbles at all.
5. Power cord wiring
In order to ensure the shaping degree and reduce the shape of the power cord, the multi-core power cord is generally required to be twisted into a circle. The mechanism of stranding is similar to that of conductor stranding. Because of the large pitch diameter of stranding, most of them adopt the non-twisting method. The technical requirements of cable forming: first, the twisted cable caused by the overturning of the abnormal insulated core; The second is to avoid scratching the insulation layer.
Most of the cables are also completed with the completion of two other processes: one is filling, which ensures the roundness and stability of the cables after the completion of the cable; One is binding to ensure that the cable core is not loose.
6. Inner sheath of power cord
In order to maintain the insulation core from being damaged by armor, it is necessary to properly maintain the insulation layer. The inner protective layer is divided into extruded inner protective layer (isolation sleeve) and wrapped inner protective layer (cushion). Wrapping cushion instead of binding belt shall be carried out simultaneously with the cabling process.
7. Power wire armouring
It is laid in the underground power line and can accept certain positive pressure effect in the task. The inner steel strip armor structure can be selected. The power line shall be laid in places with both positive pressure effect and tensile effect (such as water, vertical shaft or soil with large drop), and the structure type of internal steel wire armor shall be selected.
8. Outer sheath of power line
The outer sheath is the part of the structure to maintain the insulation layer of the power line to avoid the corrosion of environmental factors. The primary effect of the outer sheath is to improve the mechanical strength of the power cord, prevent chemical corrosion, moisture, water immersion, and prevent the power cord from burning. According to the different requirements for the power line, the plastic sheath shall be directly extruded by the extruder.