The electric wire and cable are mainly composed of three basic structural elements: conductor core, insulation layer and sheath layer.
The protective covering outside the insulating core or cable core is called the sheath of the cable (the protective covering outside the sheath is called the outer sheath). From the point of view of wire and cable sheath, braid is one of the various wire and cable sheath or outer sheath. However, according to the material used in the wire and cable braid layer and the different parts of the braid layer in the wire and cable structure, the role of braid layer is different.
Fiber braided layer
For wires, the braided layer is a form of its light protective layer. Its main function is to protect the insulation from or less by all kinds of light, heat, moisture, low temperature, acid and alkali gas erosion and external mechanical force damage, to ensure the safe operation of the wire.
For cables, fiber braid layer is often in the middle of the sheath, so as to enhance the tear strength of sheath, such as reinforced sheath is in the rubber or plastic sheath into the middle of cotton yarn, hemp fiber braid layer, in order to improve the sheath strength.
Metal braided layer
There are two kinds of metal braiding layer: copper wire braiding layer and steel wire braiding layer.The main functions of copper wire braided layer are as follows.
Shielding against electromagnetic interference, such as copper wire braided control cable, etc.
Eliminate the shielding effect of the surface potential of power cables, which shackles power lines and eliminates induction electricity, such as the total shielding of high-voltage cables.
Shielding function of safety protection. Braid copper wire outside the insulation of the main core and make good contact with the ground core or use as ground wire, which can timely reflect the leakage situation, such as shielded mine cable.
The main functions of steel wire braiding are:
Mechanical protection, such as Marine power cable CF31.
Bear longitudinal tensile force, such as WC-GC and WCT type magnetic cable used in Marine geological exploration.