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Structure composition of wire and cable

Cable structure composition

The structural components of wire and cable products can generally be divided into four main structural components of wire, insulation layer, shielding and protective layer, as well as filling components and tensile components. According to the requirements and applications of the product, some products have a very simple structure, with only one structure of wires, such as overhead bare wires, catenary wires, copper-aluminum busbars (bus bars), etc.; the external electrical insulation of these products depends on installation and laying Use insulators and space distance (that is, use air insulation) to ensure.

The vast majority of wire and cable products are products with exactly the same cross-section (cross-section) shape (ignoring the errors caused by manufacturing) and elongated products. This is because they are used as a feature of a circuit or a coil in a system or equipment. Decided. Therefore, to study and analyze the structure of cable products, only need to observe and analyze from its cross section. The following is a detailed analysis of the cable structure and cable materials:

1. Cable structure composition: Conductor

The wire is the most basic and essential component for the product to carry out electric current or electromagnetic wave information transmission function. Wire is an abbreviation for conductive core.

What are the cable conductor materials: The conductor materials are generally made of copper, aluminum and other non-ferrous metals with excellent conductivity. The optical fiber cables used in optical communication networks, which have developed rapidly in the past 30 years, use optical fibers as wires.

2. Cable structure composition: Insulation Layer

The insulating layer is a component that is wrapped around the periphery of the wire and plays a role of electrical insulation. That is to say, it can ensure that the transmitted current, electromagnetic waves, and light waves only travel along the wire and do not flow to the outside. The potential on the conductor (ie the potential difference formed to the surrounding objects, that is, the voltage) can be isolated, that is, it is necessary to ensure the normal transmission of the wire Function, but also to ensure the safety of external objects and people. Wire and insulation are the two basic components that must be equipped to form cable products (except bare wires).

What are the cable insulation materials: In today's wire and cable, the classification of cable insulation materials is mainly plastic and rubber, and there are many types of wire and cable products that are suitable for different uses and environmental requirements. Common wire and cable insulation materials include polyvinyl chloride (PVC), cross-linked polyethylene (XLPE), fluoroplastics, rubber, ethylene-propylene rubber, and silicone rubber insulation.

3. Cable structure composition: Sheath

When wire and cable products are installed and operated in various environments, they must have a component that protects the product as a whole, especially the insulating layer, which is the protective layer. Because insulating materials are required to have excellent various electrical insulation properties, the materials must have extremely high purity and minimal impurity content; often they cannot take into account their ability to protect the outside world. Therefore, for the outside world (ie installation, use occasions and ) The endurance or resistance of various mechanical forces, resistance to atmospheric environment, resistance to chemicals or oils, prevention of biological damage, and reduction of fire hazards must be borne by various protective layer structures. The main function of the cable sheath is waterproof, flame-retardant, fire-resistant, and anti-corrosion.

What kinds of cable sheathing materials are there: The cable sheathing materials mainly include rubber, plastics, coatings, silica gel and various fiber products. The rubber-plastic protective layer is characterized by softness and lightness, and it has been widely used in mobile cables. However, because rubber and plastic materials have a certain degree of water permeability, they can only be used when high-humidity-resistant polymer materials are used as cable insulation. Then some users may ask why plastic is used as a protective layer on the market? Compared with the characteristics of plastic sheath: rubber sheath has higher elasticity and flexibility, and is resistant to aging, but the process is relatively complicated. . The plastic sheath has better mechanical properties, better water resistance, abundant resources, cheap price, and convenient processing, so it is more widely used in the market.

There is also a type of metal sheath. The metal sheath has both mechanical protection and shielding functions. It also has anti-corrosion, compressive, tensile, and water-resistant properties, which can prevent moisture and other harmful substances from entering The inside of the cable is insulated, so it is widely used as a sheath for power cables with poor moisture resistance.

4. Cable structure composition: Shielding Layer

It is a component that isolates the electromagnetic field in the cable product from the external electromagnetic field; the cable product also needs to be isolated from each other between different wire pairs (or wire groups) inside. It can be said that the shielding layer is a kind of "electromagnetic isolation screen". The reason is that in addition to the function of the shielding layer is electromagnetic isolation-that is, the information transmitted in the cable product does not leak out, and does not interfere with external instruments or other lines.

Cable shielding layer material: The cable shielding layer adopts externally bound copper tape or braided copper ribbon, and the braided layer material is generally red copper or tinned copper.

5. Cable structure composition: Filling Structure

Many wire and cable products are multi-core. For example, low-voltage power cables are mostly four-core or five-core cables (applicable to three-phase systems). After these insulated cores are cabled, one is that the shape is not round, and the other is that there is a large gap between the insulated cores. Therefore, a filling structure must be added when the cable is formed. The filling structure is to make the outer diameter of the cable relatively round In order to facilitate the wrapping and extruding of the sheath, as well as to make the cable structure stable and internally strong, the force is uniform during use (when stretched, compressed and bent during manufacturing and laying) without damaging the internal structure of the cable. Therefore, although the filling structure is an auxiliary structure, it is also necessary, and its material selection and shape design also have detailed regulations.

What are the cable filling materials: Generally, the cable filling materials include polypropylene tape, non-woven PP rope, hemp rope, or recycled rubber, which is generally cheaper. It can be used as a cable filling material and must have no adverse effects on the insulated cable core.

This is cable knowledge from Henan Tano Cable.,Ltd. I hope it will be helpful to you.
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