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As fire-resistant cables are now used more and more widely, so many manufacturers are in production, but often the quality is not guaranteed. Therefore, in general, enterprises in the development of fire-resistant cable products, are first trial production of a product, the relevant national testing agencies, to obtain testing reports, on the mass production, a few cable manufacturers set up their own fire test testing room, we know, fire test is for the production of cable technology results of the test, The same process plan, at different times the production of cable performance there is a certain difference, for the production of fire-resistant cable enterprises, if the fire-resistant cable fire test rate of 99%, the fire-resistant cable on the existence of 1% of the risk of security risks, which for users is 100% of the risk,
In response to these problems, Chongqing Taishan Cable Co., Ltd. on how to improve the resistance of fire-resistant cable through the test, from the raw materials, conductor selection, production process control and so on to do a description:
1. Mica with three kinds, synthetic mica, phlogopite, Muscovite, its respective quality performance is the best synthetic mica, Muscovite the worst, for small specifications of the cable must be selected synthetic mica tape for wrapping, mica tape layering can not be used, long-term storage of mica tape easy to moisture, so in the storage of mica tape must take into account the ambient temperature and humidity.
2. Choose Mica Tape wrapping equipment, should adopt stable performance, wrap the angle of the best in the 300--400 around the package, its mica tape wrapped evenly close, all with the equipment to touch the guide wheel and Rod must be smooth, neat line, tension is not too large, the line tooling wheel side plate and cylinder body smooth. 3. For the axial symmetry of the circular core of its mica tape wrapped around the direction of the close, so for the fire-resistant cable conductor structure should be used round tight pressure conductor.
The reasons are as follows: ① Some users put the conductor as a soft structure conductor of the Strand, this requires the enterprise from the reliability of the use of cables to communicate with the user to a circular tight-pressure conductor, soft structure bundle line, complex twisted mica belt damage, as refractory cable conductor is not desirable, but some manufacturers think users need what kind of fire-resistant cable, manufacturers should meet user needs
, I think the user after all the relevant details of the cable is not very clear, the cable is closely related to human life, so cable manufacturers must be related to technical issues and users to speak clearly. ② sector conductor is not suitable, because the fan-shaped conductor of the mica tape around the pressure is uneven distribution, as shown in the diagram, it can be seen from the figure that the fan core around the Baoyun with its three sector angle of the pressure is the largest, because Mica is a flake silicate polymer, its interlayer molecular attractiveness than the crystal s1-0 covalent bond force is weak. Easy sliding between the layers, relying on silicon adhesion, but the adhesion is also low, in the external force scraping, extrusion is very easy to fall off, splitting, especially the use of fan-shaped structure, after the core of the package through the guide wheel, wire rod and line to the edge of the tooling side plate, as well as after the process of extrusion insulation into the mold core, are easy to scratch and touch, resulting in a decline in electrical performance. In addition, the section circumference of the sector conductor structure is larger than that of the circular conductor section from the cost point of view, which increases the mica tape of the precious material, although the outer diameter of the circular structure cable increases. The amount of PVC sheathed material increased, but the product material and the total cost compared to the overall cost of the circular structure cable is still economical. Based on the above explanation, from the technical and economic analysis, the conductor of the fire-resistant power cable is the best with circular structure.