How To Understand Fire-resistant Cables

- May 20, 2018-

In recent years, more and more fire-resistant cables have been used, mainly because users have recognized the performance of this cable. At the same time, the number of manufacturers of this cable is also increasing. It is very important that the quality of fire-resistant cables is guaranteed and long-term stability. of. Under normal circumstances, Henan Fangle Cable Co., Ltd. develops a series of fire-retardant cable products first. Zhengzhou Cable Factory sends inspections to relevant national detection agencies. After a detection report is obtained, it is mass-produced. There are a few cable productions. The manufacturer created his own fire-resistant test detection room. As we all know, the fire-resistance test is based on the inspection of the results of the cable technology produced. The same process plan and the cable performance produced at different times have certain differences, for the production of fire-resistant cables. If the fire resistance test rate of the fire-resistant cable is 99%, then the fire-resistant cable will have a 1% risk of safety hazard. This is 100% dangerous to the user. How to improve the fire resistance of the fire-resistant cable? The pass rate of the experiment is described as follows from the aspects of selection of raw materials, conductor selection, and production process control:

1. Some manufacturers use copper-clad aluminum conductors as cable conductor cores, but conductors for fire-resistant cables cannot use copper-clad aluminum conductors but use copper conductors.

2. For circular cores with axial symmetry, the mica tapes are tight in all directions after wrapping, so a round, tight conductor should be used for the conductor structure of the fire-resistant cable. The reason is as follows:

Some users proposed that the conductor is a stranded flexible structure conductor, which requires the company to change from the reliability of the use of the cable with the user to a circular tight conductor, soft structure beam line, complex twisting can cause mica tape damage, as a fire-resistant cable Conductors are not desirable, but some manufacturers think that users need what kind of fire-resistant cables, manufacturers should meet the needs of users, I think users are not very clear about the relevant details of the cable, the cable is closely related to the lives of people Therefore, cable manufacturers must clearly explain relevant technical issues to users. The fan-shaped conductor is also not suitable, because the pressure of the winding of the mica tape around the fan-shaped conductor is unevenly distributed. As shown in the figure, it can be seen from the figure that the stress at the three fan-shaped corners of the fan-shaped core around the mica tape is the largest. Since mica is a sheet-like silicate polymer, its intermolecular attraction is far weaker than that of the s1-O covalent bond in the crystal. The layers are easy to slide and adhere to silicon, but the adhesive strength is also low. It is easy to fall off and crack when the external force is scraped and squeezed. Especially when the fan-shaped structure is used, the core after wrapping is passed through the guide wheel and points. When the poles and cables are routed to the edges of the side plates of the tooling wheels, and the extruded insulation of the subsequent processes enters the cores, they are easily scratched and bumped, which leads to a decrease in electrical performance. In addition, the cross-sectional circumference of the sector-shaped conductor structure is viewed from a cost perspective. The length is greater than the perimeter of the circular conductor, which increases the precious material mica tape, although the outer diameter of the cable has increased. PVC sheathing material usage increased, but compared to the total cost of product materials, the overall cost of the round structure of the cable is still saving. Based on the above description, from the perspective of technical and economic analysis, the conductor of a fire-resistant power cable is preferably a circular structure.

3. Mica comes with three types of synthetic mica, phlogopite, muscovite, their respective quality performance is the best synthetic mica, muscovite worst, for the small size of the cable must choose synthetic mica tape to wrap, mica tape layering can not For use, the long-term storage of mica tape is easy to absorb moisture, so the temperature and humidity of the surrounding environment must be taken into account when storing the mica tape.

4. When using mica tape wrapping equipment, the stability performance should be good. The wrapping angle should be wrapped around 300--400, and the mica tape should be evenly packed around. All guide rollers and rods that touch the equipment must be smooth. Lines are neat and the tension is not too great. The side plates and cylinders of the tooling wheels are flat and smooth.