Electric cable & conductor

Electric Cable :
                "It is defined that the insulated conductor which is used for the purpose of electricity is known as cable"
The cable is consists of basic three parts, such as, conductor, insulation and mechanical protection.
A cable is either a stranded conductor or combination of conductors insulated from one another.
According to shape there are tow types of cables, one is circular cross-section and other is sector shaped.

Electric cables

Conductor:

                        We know that "conductor are those materials in which electric current passes through easily"

A conductor is a wire or combination of wires not insulated from one another, suitable for carrying an electric current. All metals are conductor.

A stranded conductor is a conductor composed of a group of wires. The wires in a stranded wire or a cord. Cables may be insulated or bare and insulated cables may be sheathed with lead or armoured with wires or bands.

Copper is the most commonly used conductor material in cables, because it is cheap compare to other conductor materials.

Copper has high resistance against collision and it is "jointed easily. I shows the resistivity of some materials.

         Matel                                           Resisitivity

         

          Silver                   =                    1.4 x(*) 10-6

         Copper                 =                    1.5 x(*) 10-6

         Gold                      =                      2.36

        Aluminium         =                      2.6

        Tungsten             =                      5.6

Solid and stranded conductors are used in cables. For ensure flexibility and ease of handing, conductors are stranded. A number of small wires twisted together which is equivalent to a single wire of the required size. The sizes of conductors range from lmm2 to 630mm2 . For e.g. (7/0.029) cable has a stranded conductors and every conductor size is (0.029). In flexible cable stranded are very thin, therefore elascity is very high. Stranded conductors are twisted in each other as a result, the resistance is decreased and make a fat conductor shape.

The stranded formations of stranded conductors comprised 1,3,5,7,9,37,61,127 wires etc. The reason for these odd number is that, when stranded, they form as near as possible a circular sectional shape.