Armoured cable is a type of electrical cable that offers an extra layer of protection to enhance durability and prevent damage. In this comprehensive guide, we will explore the classification, construction, applications, advantages, and differences between armoured and unarmoured cables.
Classification of Armoured Cables:
Armoured cables can be categorized into four types based on their construction and materials used:
1. Wire-Braid Armour: This type of armour is ideal when lightweight and flexible protection is required. It consists of a knitted metal braid made of materials like galvanized steel, copper, bronze, or aluminum.
2. Steel Wire Armoured Cable (SWA): SWA cables are suitable for areas with high mechanical stress and tension. These cables have multiple cores and use steel wire armour to withstand heavy pull loads. The structure of SWA cables includes a conductor (usually copper or aluminum), insulation (XLAPE or PVC), inner sheath (PVC), armour (steel wire or steel belt), and outer sheath (PVC).
3. Steel Tape Armoured Cable (STA): STA cables are designed for buried installations and can withstand external mechanical forces. However, they are not suitable for handling large tensile forces.
4. Aluminum Wire Armoured Cable (AWA): AWA cables find applications in power networks, underground installations, and outdoor and indoor settings. They are known for their non-magnetic nature, preventing induced currents in the armour due to current flow in the main conductor.
Cable Construction:
Armoured cables consist of six primary components:
1. Conductor: The conductor carries the electrical current and is typically made of copper or aluminum.
2. Insulation: The insulation layer, often made of cross-linked Polyethylene (XLP or XLPE), provides high insulation resistance, dielectric strength, and low dielectric constant.
3. Bedding: The bedding acts as a protective barrier between the insulation and the armour.
4. Armour: The armour provides a tough protective covering to the cable, enhancing its overall strength and protecting it from external forces.
5. Sheath: The sheath is an additional layer that offers further protection and holds the constituent parts of the cable together.
6. Voltage: The voltage rating indicates the maximum voltage the cable can handle safely.
Applications and Benefits of Armoured Cables:
Armoured cables are widely used in industrial applications where reliable power transmission is crucial. Their benefits include:
1. Mechanical Protection: Armoured cables safeguard the internal wiring from external forces like impacts, crushing, or abrasion.
2. Moisture Protection: The outer layer of armoured cables protects against moisture, preventing corrosion and damage.
3. Environmental Resistance: Armoured cables are designed to withstand harsh environmental conditions, including extreme temperatures, UV radiation, and chemical exposure.
4. Longevity: The added protection from the armour layer increases the lifespan of the cable, reducing the need for frequent replacements or repairs.
5. Safety: Armoured cables comply with safety standards and regulations, minimizing the risk of electrical hazards such as short circuits or fires.
6. Versatility: These cables find applications in industrial, commercial, and residential settings, making them a versatile option for various electrical wiring needs.
7. Enhanced Performance: The armour layer improves cable performance by reducing signal interference and improving transmission quality.
8. Cost-Effectiveness: Despite the higher initial cost, armoured cables offer long-term cost savings due to their extended lifespan and reduced maintenance requirements.
Difference between Armoured and Unarmoured Cables:
Armoured and unarmoured cables differ in construction and protective features:
1. Construction: Armoured cables have an additional layer of armour, whereas unarmoured cables lack this protective layer.
2. Protective Features: Armoured cables provide protection against mechanical damage, moisture, UV radiation, and chemicals, while unarmoured cables lack these protective features.
3. Applications: Armoured cables are suitable for industrial and commercial environments with harsh conditions, while unarmoured cables are commonly used in residential and light commercial settings where the risk of damage is lower.
4. Cost: Armoured cables are generally more expensive due to the added protective layer. However, their longer lifespan and reduced need for repairs or replacements can result in cost savings in the long run.
Conclusion:
Armoured cables are vital for transmitting power in harsh environments. They come in various types, each suited for specific applications. The construction of armoured cables includes several components that contribute to their durability and performance. Understanding the benefits of armoured cables, such as mechanical and moisture protection, environmental resistance, longevity, and enhanced safety, can help in making informed decisions about their usage. Armoured cables offer distinct advantages over unarmoured cables, primarily in terms of protection and suitability for different environments. While armoured cables may have a higher upfront cost, their long-term cost-effectiveness and reliability make them a preferred choice in many industrial and commercial settings.
