Selection of Flame Resistant Cable

1. Flame resistant cable

The so-called flame resistant cable is a cable that can maintain normal operation for a certain period of time under specified flame conditions, or a cable that can maintain a complete circuit under burning conditions. The selection of conductor materials, mica tape, insulating materials, and auxiliary materials for flame resistant cables is described as follows.

2. The choice of flame resistant cable materials

(1) Selection of conductor material and conductive core structure

The melting point of aluminum conductor is 685℃, and the temperature of fire-resistant cables must reach 750℃. Obviously, aluminum conductors cannot be used as flame resistant cable; the melting point of copper is above 1,000℃, so it can be used as conductors for flame resistant cable.

Copper wire with a cross-section of 1.0mm² and below does not melt at high temperatures, but as the core is too thin, it is easy to break due to local overheating and slight external influences, and lose the normal energizing function. Therefore, it is not recommended to use copper wires of 1.0mm² and below as fire-resistant cables.

The unevenness of the conductor surface will cause great damage to the mica tape, and the performance of the produced flame resistant cable is unstable.

Large cross-section cable sector core conductors are not easy to make flame resistant cable and round core conductors are suitable for fire proof cable. As the surface of the circular structure is smoother than that of the fan-shaped structure, the force of the mica tape is more uniform and will not cause damage to the mica tape, and the circular structure saves the mica tape and has a lower cost than the fan-shaped structure.

(2) The selection of mica tape

According to actual production conditions, phlogopite and synthetic mica are mostly used. The refractory temperature of synthetic mica is higher than that of phlogopite. In actual production, fire-resistant mica tape can be selected according to customer requirements. Considering the safety of flame-resistant cable and ensuring the quality and stability of flame-resistant cable, it is recommended to use synthetic mica.

(3) The selection of insulating materials

The commonly used insulating materials for fire-resistant cables are mostly PVC, PE, XLPE and so on but the effect of using PE and XLPE is better than that of PVC, since at a high temperature of 750+50℃, the insulating material of the cable has already burned and no longer exists, but different insulation residues have different impacts on the mica tape.

The main components of PVC are PVC resin and CaCO₃, which adhere to the outside of the mica tape according to its combustion mechanism. The mixture of its combustion solid residue Cao-CaCl₂ is in a relatively stable state and adheres to the outside of the mica tape during the combustion process. It will generate internal stress, squeeze the mica tape, damage the mica tape, and affect the fire resistance.

PE and XLPE are pure hydrocarbons with almost no fillers. The combustion products of CO₂ and water vapor escape naturally, and only a small amount of solid impurities remain on the mica tape, which will not cause damage to the mica tape. Therefore, PVC, PE, XLPE can be used for fire-resistant insulation but the PE and XLPE is better.

(4) The selection of auxiliary materials

Although the tape and filling of the auxiliary materials are not the key materials, they should be selected according to the principle of the least residues generation after combustion.

As one of the leading cables manufacturers, Jenuincable can offer the following cables:

ABC cable, Xlpe cable, Yy cable, PVC insulated cable, Fire-rated cables, Orange cable, etc.