CONSTRUCTION OF UNDER GROUND CABLE

General Construction of the underground cable is shown in the below figure.

there is the main part of Under the ground cable is,

1) CORE

2) INSULATION

3) METALIC SHEATH

4) BEDDING

5) ARMOURING

6) SERVING

 

Now we will discuss all the part of underground cable in step by step.

1) CORE

The function of the core is to carry current. its made up of copper or aluminium and stranded core is used. there is flexibility is increase due to stranding. a core is placed at the centre of the cable.

following types of core used in an underground cable.

"1 core, 2 core, 3core, 3.5 core, 4 core"

2) INSULATION

Insulation is placed above the core & it is necessary between the conductor and earth in single-core the cable also between conductors and earth in multi-core cable.

there are different types of insulations are used like paper, varnished cambric, rubber, vulcanised bitumen, oil-impregnated paper, PVC, metalized paper etc used for insulation in different applications.

3) METALIC SHEATH

metallic sheath is placed above the layer of insulation. moisture is a major enemy of insulation. when moisture enters in the insulation its dielectric strength will be decreased. so we must be careful that moisture doesn't enter in insulation. For that metallic sheath is placed above the insulation. sometimes metallic core is a form of aluminium when a core is made of copper.

4) BEDDING

bedding is used to protect the sheath from mechanical damage and place above the metallic sheath. tape of jute is wound over the metallic sheath.

5) ARMOURING

armouring is placing above the bedding and its use to protect the cable from mechanical damage. there is two layers of steel tape or galvanized steel wires are wound over the bedding.

6) SERVING

The layer of jute is provided over the armouring which is called serving. serving is placed above the layer of armouring.