The cable usually consists of several or several sets of wires, each of which is twisted at least two, similar to a rope. Each set of wires is insulated from each other and often twisted around a center, and the entire outer bread has a highly insulating cover. Wire and cable are used to transmit, distribute, or transmit electrical signals. The wire and cable consists of four parts: a conductive core, an insulating layer, a sealing sheath and a protective covering.
First, the conductive core: made of high conductivity material (copper or aluminum). Depending on the requirements of the laying conditions for the softness of the cable, each core may be stranded from a single wire or multiple wires.
Second, the insulation layer: the insulation material used as the cable should have a high insulation resistance. Commonly used insulating materials in cables are oil-impregnated paper, polyvinyl chloride, polyethylene, cross-linked polyethylene, and rubber.
Third, the sealing sheath: protect the insulated core from mechanical, moisture, moisture, chemicals, light and other damage. For moisture-sensitive insulation layers, lead or aluminum extrusion seals are generally used.
Fourth, the protective cover: to protect the sealing sheath from mechanical damage. Generally, galvanized steel strip, steel wire or copper strip, copper wire, etc. are wrapped around the sheath (called armored cable), and the armor layer can simultaneously shield the electric field and prevent external electromagnetic wave interference. In order to avoid the corrosion of the steel strip and the steel wire by the surrounding medium, it is generally coated with asphalt or wrapped with impregnated jute layer or extruded polyethylene or polyvinyl chloride sleeve.