Armoured is the name given to any electrical cable constructed with a layer of aluminium wire armour or steel wire armour. The armour sits below the sheath of the cable to provide protection for the conductor and insulating layers.
armouring must have mechanical protection. Aluminium wire armour or AWA, and steel wire armour or SWA, provide such protection – as well as enabling the cable to withstand higher pulling loads.
Metallic armour are used when cables have to be installed direct buried, or if mechanical
protection is required.Following points must be considered:
■■ Required tensile load
■■ Expected pressure on cable during service
■■ Protection against rodent
■■ Protection against accidental damage
■■ Minimum required bending radius
SWA: single layer of galvanized steel wires, with diameters according to relevant standards,
coverage min. 90%. This armour assures a very good mechanical protection and tensile
strength. An additional counterspiral tape increases solidity, if required.
GSWB: galvanized steel wire braid, diameter of wire: 0.20 – 0.25 – 0.30 – 0.40 mm, with
coverage of > 80%. It assures a good mechanical resistance, allowing a lower bending radius
compared to other armour. It is preferable when there is movement or vibration.
For special application is possible to use stainless steel, tinned copper or special alloy wires.
GSTA: galvanized steel tape armour, composed by two tapes with overlapped edge; thickness
of each tape: 0.20 – 0.30 – 0.40 mm, according to cable diameter. It grants a coverage > 100%.
Very good crush resistance, but fair tensile strength. Brass tape of minimum thickness 0.075
mm can be used for special applications.
GSFA: galvanized steel flat armour. It is composed by flat wire of thickness 0.6 mm or 0.8 mm,
it is similar to SWA, but with higher mechanical protection.