Wires and cables are mainly composed of three basic structural elements: conductor core, insulation layer and sheath layer

Wires and cables are mainly composed of three basic structural elements: conductor core, insulation layer and sheath layer

There is no strict distinction between wires and cables, but in a broad sense, the cable structure is more complex, it has a complex sheath layer, while the wire structure is relatively simple, some have only conductor and insulation layer, some have only woven and waxed light protective layer or coated with a light soft protective layer. The conductive core of the electric wire cable is used to transmit current. In order to reduce power loss and voltage drop, The conductive wire core is generally made of copper and aluminum with high conductivity. The role of the insulating layer is to prevent current leakage along the radial direction and ensure safe use. Therefore, the insulating layer is required to have good electrical insulation, heat resistance and certain mechanical strength

The protective covering layer outside the insulated core or formed cable core is called the sheath of the cable (the protective covering layer outside the sheath is called the outer sheath). The main function of the sheath is to protect the insulating layer. Its main performance is moisture-proof, oil proof, anti-corrosion, sun aging resistance, flame resistance, and mechanical protection (the role of the outer covering layer is mainly to strengthen the mechanical protection of the cable. It bears tension, bumps). It also has the functions of electricity protection, magnetic resistance, dry resistance, etc

From the perspective of wire and cable sheath, braiding is one of many kinds of sheath or outer sheath of wires and cables. However, according to the materials used for wire and cable braiding and the different parts of the braiding in the wire and cable structure, the role of the braiding is obviously different

1、 Function of fiber braid

For electric wires, fiber woven layer is a form of its light protective layer. Its main function is to protect the insulation from or less from the corrosion of light, heat, moisture, low temperature, acid and alkali gases, and external mechanical forces to ensure the safe operation of the wire. For cables, the fiber woven layer is often in the middle of the protective layer to enhance the tear resistance of the protective layer, For example, the reinforced sheath is to add cotton yarn, hemp and other fiber braids in the middle of the rubber or plastic sheath to improve the strength of the sheath

2、 Function of metal braid

The metal braided layer mainly includes copper wire braided layer and steel wire (iron wire) braided layer,

The main functions of copper wire weaving are:

L Shielding function against electromagnetic interference, such as blue cable braided with tinned copper wire, control cable braided with copper wire, etc

2. Eliminate the shielding effect of surface potential of power cables. It can bind power lines and eliminate induced electricity, such as the general shielding of high-voltage cables

3. Shielding function of safety protection: braid copper wire outside the main core insulation and make good contact with the ground core or use it as ground wire, which can timely reflect the leakage situation, such as shielded mining cable.

The main functions of wire braiding are:

l. Mechanical protection, such as marine power cable CF31

2. Bear the longitudinal tensile force, such as the magnetic measuring cables WC - GC and WCT for marine geological exploration

3. Magnetic field shielding.