The copper and aluminium wire rods are drawn on wire drawing machines. With the help of dies of various sizes, the drawing is done according to the diameters specified by the IS standards. In case of Copper, on line annealing is done along with the drawing which helps in the removal of excessive voids, inclusions and other internal wire defects. The diameter of drawn wire is maintained in close tolerance.
Conductor Making Stage
The conductors for Cables are made from High Conductivity EC grade Aluminium and are manufactured according to IS-8130/1984. The copper used is annealed and of high conductivity.
For all cables having two more cores, a common covering (inner sheath) is provided over the laid up cores either by extrusion or by wrapping of plastic or proofed tapes. Single core cables do not require inner sheath. This is done after the cores are laid up together.
Depending upon the application, the cables can be armoured. This provides better mechanical strength to the product. The armouring can be of Steel Strips / Round Wires. In case of cables where diameter over the inner sheath does not exceed 13 mm, the armour shall consist of Galvanized Round Steel Wires; above this size, the armour can be Galvanized Flat Steel Strips or Galvanized Round Steel wires as per the customer’s requirement.
Outer Sheath Stage
Over the armouring, or in case of un-armoured cables, over the inner sheath (for single core cables over the insulation), a tough outer sheath of PVC is done. The trademark ‘AVOCAB’ along with the ‘year’ and code of manufacture are embossed on the outer sheath. Wherever desired, the customer name can also be embossed on the cable. The embossing script repeats at desired length of cable. Sequential marking shall be provided if required by purchase at every meter of the cable. In case of AVOCAB LT Cables with heat resisting insulation, the word ‘HR85’ is also embossed. Fire Retardant Low Smoke (FRLS) Sheathing is also provided if required.
The conductors are insulated with suitably compounded PVC/ XLPE which is applied to the conductor by extrusion process.
Cores are identified by colour scheme of the insulation. The following colour scheme is adopted:
|(a)||1 cores||–||Red, Black, yellow or blue|
|(b)||2 cores||–||Red and Black|
|(c)||3 cores||–||Red, yellow and blue|
|(d)||4 cores||–||Red, yellow, blue and black (Reduced neutral core is also black)|
|(e)||5 cores||–||Red, yellow, blue, black and light grey|
|(f)||For cables having more than 5 cores||–||Two adjacent cores (counting and direction) in each layer are coloured
blue & yellow respectively and the remaining cores are light grey.