Underground Cable

Construction of Underground Cables


An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by some protective layer. Normally, electric power can either be transmitted using over head lines or underground cables.

 There are various parts of a cable to be taken care of during construction. The power cable   mainly consists of:
 
  1. Conductor
  2. Insulation
  3. LAY for Multi core cables only
  4. Bedding
  5. Beading/Armoring (if required)
  6. Outer Sheath
                             electrical power cable

1.Conductor

       Conductors are the only power carrying path in a power cable. Conductors are of different materials. Mainly in the cable industry, we use copper and aluminum conductors for power cables.


2.Insulation

       The insulation provided on each conductor of a cable by mainly PVC (Poly Vinyl Chloride), XLPE (Cross linked Polyethylene), RUBBER (Various Types of Rubber). The insulating material is based on operating temperature.

3.Beading (Inner Sheath)

     This portion of the cable is also known as the inner sheath. It works as binder for insulated conductors together in multi-core power cables and provides bedding to Armour. This portion of the cable is mainly made of PVC.

4.Armoring

      Armoring is provided over the bedding to protect the cable from mechanical injury during its handling and lying. It consists of one or two layers of galvanized steel wire or steel tape. In some cable, armoring is not provided.


5. Beading

      Over the metallic sheath is applied a layer of bedding which consists of a fibrous material like jute or hessian tape. The purpose of bedding is to protect the metallic sheath against corrosion and from mechanical injury due to armoring.


6.Outer Sheath

     This is outermost cover of the cable normally made of PVC (Poly Vinyl Chloride), RUBBER (Various Types of Rubber) It is provided over the armor for overall mechanical, weather, chemical and electrical protection. Outer sheath is protection offered to cable not much electrically but more mechanically.

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