How to choose wire and cable insulation materials?

Insulation is the material of the outermost layer of overhead insulated cables, usually refers to the material that blocks the passage of heat, electricity or sound, and has excellent weather resistance.



                 How to choose insulation and sheath materials according to the place of use?

1. The applicable temperature range of ordinary PVC wires and cables is -15°C~60°C. When the ambient temperature of the use site exceeds this range, special PVC wires and cables should be used; ordinary PVC wires and cables will emit toxic emissions during the combustion process. Flue gas is not suitable for use in densely populated places such as underground passenger transport facilities, underground commercial streets, and important public facilities.


2. XLPE wires and cables do not have flame retardant properties, but they will not produce a lot of toxic fumes when burning, which is suitable for the requirements of "clean" industrial and civil buildings.


3. Rubber wires and cables have good bending properties and can be laid in cold climates, and are suitable for places with large horizontal height differences and vertical laying; rubber wires and cables are suitable for electrical circuits of mobile electrical equipment.



Characteristics of different cables

Flame retardant wire and cable

Flame retardant wire and cable refers to the performance of the flame retardant cable that burns under the specified test conditions, which can only make the flame spread in a limited range. The performance of flame-retardant cables that can self-extinguish within a limited time after the fire source is removed is mainly evaluated by the oxygen index and the smoke index. Since oxygen makes up 21% of the air, materials with an oxygen index over 21 will self-extinguish in the air. The higher the oxygen index of the material, the better the flame retardant performance. According to the characteristics of the smoke during the combustion process, flame-retardant cables can be divided into three categories: general flame-retardant cables, low-smoke and low-halogen flame-retardant cables and halogen-free flame-retardant cables. Directly buried cables, directly purchased building holes or masonry cables, and wires and cables laid through pipes can choose ordinary wires and cables. Cables run in cable ducts with cover slots and covers. If the measures such as blockage, water blocking and isolation are removed, the first-level flame retardant requirements can be reduced.


Fire-resistant wire and cable

1. Fire-resistant wire and cable refers to the cable that can maintain normal operation characteristics under the specified test conditions during the flame burning for a certain period of time.

2. According to the insulating material, fire-resistant cables can be divided into organic and inorganic types. The organic type mainly uses 800 refractory high temperature mica tape with 50% overlapping coverage to cover two layers as the refractory layer; the external insulation is made of polyethylene or cross-linked polyethylene. Insulating materials can be used when flammable materials are used.

3. Fire-resistant wires and cables are mainly suitable for lines that still need to maintain normal operation in the event of fire.

4. Determine the fire resistance class according to the flame temperature that may be reached in the event of a fire.


What kind of cable jacket is a qualified product?


What are the hazards of unqualified sheaths?

1. Reduce the service life of wire and cable products

Due to the long-term operation of the cable, it is extremely susceptible to corrosion by external media, and the insulation level and mechanical level of the thinnest point of the sheath will decrease, especially if it is directly buried, immersed in water, exposed to the open air or easily corroded. Combined with routine jacket test detection or a line ground fault, the thinnest point may be broken down. In this way, the function of the cable jacket is lost.


2. Increase the difficulty in the laying process

With the development of the global industry, more and more environments require high-voltage cable products to have a small outer diameter. In the process of laying, it is necessary to consider leaving a gap, so as to dissipate the heat generated by the wire and cable after power-on, and the thickness of the sheath. Excessive thickness will increase the difficulty of laying, so the thickness of the sheath must strictly comply with the relevant standards, otherwise it will not be able to protect the wire and cable.

According to the above description, we can know that the quality of the product is good or bad, and its first characteristic is reflected from the appearance quality of the product. We strictly pay attention to the appearance quality, and strictly control and inspect it.


The role of cable sheath

The sheath is the appearance of the cable, and its appearance requirements are smooth and round, uniform in luster, no eccentricity, no mechanical damage, flattening, no visible sundries, bubbles, blisters, obvious particles, slub-shaped, twist-shaped, etc. , and also pay attention to the influence of the thickness of the sheath on the quality of the cable.


The biggest function of the cable sheath is to protect the insulating core of the cable from being damaged under the action of external force, which plays a protective role. If the thinnest point of the cable sheath does not meet the requirements, the cable sheath will be damaged without reaching the normal maximum external destructive force.


To sum up, when we choose or produce wires and cables, we also operate in strict accordance with the production standards.