Conductor: conductor of current objects, wire and cable specifications are expressed in terms of the cross-section of the conductor.
Insulation: the insulating material according to the requirements of the degree of voltage resistance, with different thicknesses of the outside of the conductor and become.
Protective layer: the part of the cable that protects it.
Why the cable armored and stranded armored cable refers to the cable with a metal material armored protective layer, the cable plus the purpose of the armored layer in addition to enhance the tensile strength, compressive strength and other mechanical protection to extend the service life, but also through the shielding protection to improve the cable's anti-interference properties.
Commonly used armoring materials are steel tape, steel wire, aluminum tape, aluminum tube, etc., of which steel tape, steel wire armor layer with high permeability, has a very good magnetic shielding effect, can be used for low-frequency interference, and can make the armored cable laying and free from direct burial through the tube and inexpensive in the actual use of more.
Different specifications of different numbers of copper wires according to a certain arrangement of order and stranding distance stranded together, it becomes a larger diameter conductor, this stranded large diameter stranded conductor than the same diameter size of a single branch of the copper wire is more soft to make a good bending performance of the wire, the pendulum test is not easy to break for a number of requirements for the soft wire (let's say that the medical grade wire) is more likely to meet the requirements.
From the electrical performance: after the conductor is energized, due to resistance to consume electrical energy and heat. As the temperature rises will affect the insulation and protective layer material performance life. In order to make the cable efficient operation, should increase the conductor cross-section, but the large cross-section of a single wire is not easy to bend, poor flexibility, is not conducive to the production and transportation and installation and laying. From the mechanical properties and the requirements of flexibility, reliability, multiple single line twisted together stranded, you can solve the contradiction.