Sep. 05, 2024
A cable consists of an outer protective layer, conductor insulation, and the conductor itself. The key difference between armoured and non-armoured electrical cables is the presence of an additional armoured layer in armoured cables. This armoured layer can be made of three types of metal: steel tape armour, thin steel wire armour, and thick steel wire armour.
A. What Exactly Is an Armoured Electrical Cable?
An armoured electrical cable is one that has a metal protective layer around it. The objective of the cable plus armour layer is to improve the anti-interference performance of cables by shielding protection as well as the service life of mechanical protection such as tensile strength and compressive strength.
Common armouring materials for cables include steel tape, steel wire, aluminum tape, and aluminum tube. Among these, steel tape and steel wire are particularly valued for their high magnetic permeability and effective magnetic shielding. Armoured cables are often installed directly, without the need for protective pipes, making them a more practical and cost-effective solution.
Adding an armoured layer enhances the mechanical strength and corrosion resistance of any cable structure. These cables are specifically designed for environments prone to mechanical damage and corrosion. They can be installed in various ways, though direct burial in rocky terrains is ideal. To prevent interference with power transmission through the armour, it is important to ensure a large bending radius and to ground the armour layer for added protection. The armoured layer not only extends the service life of the cable by providing mechanical protection, such as improved tensile and compressive strength, but it also resists external forces that could affect the cable's performance.
B. Purpose of Armoured Electrical Cables
Armoured electrical cables are designed with a tough outer layer to effectively shield the conductor from external damage. These cables are commonly used in harsh environments, especially for direct burial applications. They offer high resistance to corrosion from acid rain, protection against animal bites, and provide enhanced safety, stability, and reliability.
While cross-linked cables utilize cross-linked polyethylene (XLPE) as the insulation layer around the conductor, armouring involves wrapping the cable's outermost layer with steel tape or steel wire. This armoured layer provides additional protection against mechanical damage. Armoured XLPE cables combine both features, offering enhanced durability through their cross-linked insulation and the protective armoured layer.
C. Uses of Armoured Electrical Cables
1) Power Systems:
Armoured electrical cables are widely used in power systems, including overhead bare wires, bus bars, power cables, branch cables, magnet wires, and electrical equipment cables. These cables provide enhanced protection and durability for power distribution and equipment connections.
2) Information Transmission Systems:
In information transmission, armoured cables are used for various applications such as local telephone lines, TV cables, electronic cables, radio frequency cables, fiber optic cables, and data or composite cables. These cables ensure secure and reliable data transmission, especially in challenging environments.
3) Mechanical Equipment and Instrumentation Systems:
Armoured electrical cables are used extensively in mechanical equipment and instrumentation systems, particularly power cables, electromagnetic wires, data cables, and instrumentation cables. These cables offer enhanced protection against physical damage and environmental conditions.
The application of direct burial technology for armoured electrical cables has expanded into many fields, representing significant advancements in science and technology. This innovation highlights the potential for broader use across various industries and locations.
D. Advantages of Armoured Cables Over Unarmoured Cables for Electrical Transmission
The primary difference between armoured and unarmoured cables lies in the additional metal reinforcement present in armoured cables. This reinforcement typically comes in the form of steel tape or steel wire armouring, with the latter available in both thin and thick variations. The key advantages of using armoured cables include:
1. Enhanced Protection Without Conduit: Armoured cables provide the necessary protection and durability without the need for electrical conduit, elbows, expensive offsets, or conduit couplings.
2. Corrosion Resistance: The metal armour is resistant to corrosion, making it suitable for use in wet or harsh environments.
3. Flexibility and Durability: Unlike rigid conduit or continuously welded armour, interlocked armour offers flexibility, ensuring that the armour absorbs impacts without damaging the inner conductors. This makes it easier to install in spaces with complex or tightly spaced bends where conduit installation would be difficult.
4. Simplified Installation: Armoured cables do not require specialized tools for cutting or bending, making installation more efficient and cost-effective.
