In recent years, the demand for fire-resistant cables has been on the rise, primarily due to the recognition of their performance by users. Concurrently, the number of manufacturers producing these cables has been increasing. Ensuring the quality and long-term stability of fire-resistant cables is of paramount importance. Typically, some companies first trial-produce a segment of the cable, send it for testing to relevant national detection agencies, and only proceed with mass production after obtaining the detection report. A few cable manufacturers have established their own fire-resistant testing detection rooms. Fire-resistant testing is a check on the process results of the cables produced. The same process scheme can result in varying performance of cables produced at different times. For companies producing fire-resistant cables, if the pass rate of the fire-resistant test is 99%, there is still a 1% risk of safety隐患 in the fire-resistant cables. This poses a 100% risk to users. In response to these issues, the following discusses how to improve the pass rate of fire-resistant cable tests from aspects such as raw materials, conductor selection, and production process control.
1. Utilizing copper conductors
Some manufacturers use copper-clad aluminum conductors as the core of cable conductors; however, for fire-resistant cables, copper-clad aluminum conductors should not be chosen and copper conductors should be used instead.
2. Opt for circular tightly compressed conductors
For circular cores with axial symmetry, the mica tape wrapping is tight in all directions, thus the conductor structure of refractory cables is best suited for circular compressed conductors.
The reason is: some users suggest using stranded soft structure conductors, which requires enterprises to communicate with customers and switch to circular tightly compressed conductors. Soft structure stranded wires and multiple twists can easily damage mica tape, which is not advisable for fire-resistant cable conductors. However, some manufacturers believe that if the user requires a certain type of fire-resistant cable, the manufacturer should meet their needs. After all, users are not very knowledgeable about the specific details of cables. Cables are closely related to human life, so cable manufacturing companies must clearly explain the relevant technical issues to customers. The fan-shaped conductors are also not suitable, as the mica tape wrapping pressure in fan-shaped conductors is uneven, which can easily cause scratches and collisions, leading to a decrease in electrical performance. Moreover, from a cost perspective, the cross-sectional circumference of fan-shaped conductor structures is greater than that of circular conductor structures, which increases the precious material mica tape. Although the outer diameter of circular structure cables is slightly larger, the increased usage of polyvinyl chloride sheath material, when compared to the total cost, the overall cost of circular structure cables is still lower. Based on the aforementioned, a technical and economic analysis indicates that using circular structures for the conductors of fire-resistant power cables is the most advantageous choice.
