Fire-resistant wire and cable is a general term for wire and cable with fire resistance, and is usually divided into two types: fire-retardant wire and cable and fire-resistant wire and cable.
1, flame retardant wire and cable
Flame retardance refers to retarding and retarding the spread of flames along wires and cables so that the fire does not expand. This type of cable has self-extinguishing properties after ignition.
Fire-retardant cables can be divided into three grades according to the national experimental standard (GB12666-99): ZRA, ZRB, ZRC. In the general product nomenclature, ZRA is usually represented by GZR, which is referred to as a high flame-retardant cable or an oxygen barrier cable or a highly flame-retardant oxygen barrier cable. ZRC represents ZR in general flame retardant products.
Flame-retardant cables are self-extinguishing at the same time as maintaining the electrical performance and physicochemical properties of ordinary cables, that is, they are not flammable, or when the cable ignites or catches fire due to its own ignition or an external ignition source, the cable does not continue after the ignition is extinguished. Burning, or burning time is very short (within 60 minutes), or the length of flame propagation is very short.
Halogen-free flame-retardant cables have the advantages of low toxicity, low smoke and halogen-free compared to halogen-containing flame-retardant cables. Flame retardant level is not high, basically is C class. The reason is that the oxygen scavenging efficiency of halogen radicals is greater than the energy efficiency of non-halogenated flame retardants.
The oxygen barrier flame retardant technology is mainly filled with a layer of inorganic metal hydrate between the cable insulation core and the cable jacket. It is a non-toxic, odorless, halogen-free white gel. Oxygen-insulated flame retardant cables can be applied to low, medium and high voltage power cables, control cables and communication cables without changing the cable structure and raw material parameters, and make the cable flame-retardant class A.
2, fire-resistant wire and cable
Refractory refers to the operation of maintaining a certain period of time under the condition of flame combustion, ie, maintaining the integrity of the circuit. This type of cable has a power supply capability for a certain period of time in the flame.
Fire-resistant cables according to national experimental standards (GB12666-99) can be divided into two levels: NHA, NHB; In the general product naming, NHA is usually expressed with GNH, is called high fire-resistant cable. NHB is represented as NH in general refractory products.
Fire-resistant cables can continue to work (transmitting current and signals) in the event of a fire, and their own prolonged combustion is not included in the assessment. Fire-retardant cables quickly stop working in the event of a fire. Its function is to prevent self-extinguishing due to non-flammable and non-spreading. The fire-resistant cable maintains normal operation for 180 minutes during flame combustion at 750-800°C.
Fire protection cable is actually another type of fire resistant cable. It is made of copper as the conductive core, seamless copper tube as the sheath, and inorganic mineral magnesium oxide as the insulating material group.
Since the whole is composed of inorganic materials, the entire fire-resistant cable neither burns nor burns. And can withstand the fire. Tests have shown that when the flame is fired at 800-900°C for 2 hours, the cable is normally energized and operating, and the flame is still intact after being burned under a flame of 1000°C for 30 minutes, and the normal operation continues. The normal working temperature is 250°C and it can run safely and reliably.
In addition, this kind of fireproof cable is also called mineral cable (Internationally known as MI cable).
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