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The material generally used for armour of high voltage cables is
Copper
Brass
Aluminum
Steel
Steel
The armour of a high voltage cable is primarily provided for mechanical protection. Galvanized steel wire or steel tape is used as the armouring material because of its high mechanical strength and ability to withstand the external stress applied during installation and operation.
The armour of a high voltage cable is primarily provided for mechanical protection. Galvanized steel wire or steel tape is used as the armouring material because of its high mechanical strength and ability to withstand the external stress applied during installation and operation.
FmechтАЛтИЭ╧ГtensileтАЛтЛЕAarmourтАЛ тАФ where FmechтАЛ represents mechanical load capacity and AarmourтАЛ is the cross-sectional area of steel.
The cable is subjected to mechanical stresses like crushing, impact, or tensile loads during laying in trenches or ducts. Steel armour provides a robust metallic sheath that prevents the insulation and the conductor from mechanical damage. Additionally, in some designs, the metallic armour provides a low-resistance path for fault currents to ground, aiding in the operation of protective relays.
Armour prevents mechanical injury during handling, laying, and backfilling.
Galvanized steel is preferred to prevent corrosion in underground environments.
For single-core AC cables, non-magnetic armour (like Aluminum) is sometimes used to avoid eddy current losses, but for general HV cable questions, Steel is the standard answer.
The armour is usually placed over the bedding layer, which protects the lead sheath.
High mechanical impact resistance
Cost-effective material
Provides longitudinal strength during cable pulling
Increases the overall weight of the cable
Increases cable stiffness, making it harder to bend
Susceptible to corrosion if the outer serving is damaged
Direct burial in soil
High-voltage underground transmission
Industrial cable trays requiring mechanical protection
Standard specifications for cable armouring are often defined by IS 7098 or IEC 60502.
Option A (Copper) and C (Aluminum) are excellent conductors but lack the necessary hardness and tensile strength for mechanical armouring. They are instead used as the central conducting core.
Option B (Brass) is rarely used due to its high cost compared to steel.
D is correct тАФ Steel is the standard material used for the armouring of high voltage cables to provide necessary mechanical strength.
Always distinguish between the 'conductor' material (Copper/Aluminum) and the 'armour' material (Steel) in cable questions. High conductivity is required for the core, while high mechanical durability is required for the armour.