The fire-resistant power cable is a cable that can operate safely for a certain period of time in the presence of a flame,which is different of flame retardant power cable and low-smoke halogen-free cable.
Because the aluminum conductor is not resistant to high temperatures, the fire-resistant power cables use copper conductors and the conductors are tightly stranded circular conductors.
Circular pressed copper conductors have many advantages over fan-shaped conductors: When mica tapes are wrapped, mica and conductors are tightly integrated, which is conducive to the even distribution of power plants and enhances the electrical insulation performance of cables.
At the same time, the amount of mica tape can be saved and the cost can be reduced. .
Outside the conductor with two or more layers of mica tape wrapped around, the overlap rate in production is usually not less than 30%, due to the different properties of mica tape, sometimes overlapping rate of 50% to meet the fire test requirements, so that the mica tape winding situation It is based on the fire test.
When wrapping the refractory mica tape, the size of the cross-section of the conductive core also affects the wrapping process.
The width, thickness, and cover ratio of the mica tape should be correctly selected in the production, and the wrap angle should be selected to avoid leakage and breakage.
To reduce crevices and pleats; do not allow bonding of materials with volatile materials at the mica tape cover joints.
The insulating layer of the fire-resisting power cable is wrapped with two or more layers of refractory mica tape outside the conductor.
The insulation thickness of the cable with conductor cross-section of 25 mm2 and above is allowed to be reduced by 20%, but it can be based on the fire-resistant cable test.
The characteristics of maintaining the current in the fire during the fire, that is, the fire resistance characteristics are ensured by the synergistic effect of the entire cable line structure.
Therefore, in theory, there is no need to use the flame retardant cable material for the insulation and sheathing of the cable.
Usually, the actual Only the flame retardant sheathing material is selected in the production, but only when the customer specifically requests it or when it is used in a special occasion, the flame retardant insulating material or the core is used to wrap the flame retardant tape or increase the flame retardant oxygen barrier layer.
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