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Aluminum conductor cable can be joined by
Gas welding
Soldering
Compression
Thermit welding
Compression
Compression jointing is the preferred industrial method for connecting aluminum conductors, particularly for underground power cables. It involves using a crimping tool to plastically deform a metal connector sleeve around the conductor, ensuring a low-resistance, high-strength mechanical and electrical connection.
Compression jointing is the preferred industrial method for connecting aluminum conductors, particularly for underground power cables. It involves using a crimping tool to plastically deform a metal connector sleeve around the conductor, ensuring a low-resistance, high-strength mechanical and electrical connection.
R=╧БALтАЛ тАФ Resistance formula relating resistivity, length, and cross-section, which must be kept low at the joint.
F=P├ЧA тАФ Force exerted by the hydraulic crimping tool to ensure metal deformation.
The process relies on the principle of cold pressure welding. When high hydraulic or manual force is applied via a crimping die, the oxide layer on the surface of the aluminum strands is broken due to mechanical shear, allowing intimate metal-to-metal contact between the strands and the connector sleeve. This creates a permanent, gas-tight bond that prevents the ingress of moisture, which is critical for aluminum as it is prone to rapid re-oxidation.
Aluminum forms a stable and non-conductive oxide layer (Al2тАЛO3тАЛ) that must be broken to ensure conductivity.
Compression joints are superior to soldering for aluminum because soldering is difficult due to the oxide layer and potential galvanic corrosion.
Correct die selection is mandatory to ensure the correct compression ratio for the cable cross-section.
Joints must be designed to withstand tensile forces and thermal expansion cycles.
High mechanical strength
Excellent electrical conductivity
Gas-tight seal prevents oxidation
No heat application required
Requires specialized, heavy hydraulic tools
Die size must exactly match the conductor size
Irreversible connection process
Underground LV and MV power cable jointing
Overhead transmission line splicing
Grounding system connections
Soldering (Option B) is generally unsuitable for aluminum because the flux required to remove the oxide is highly corrosive to the metal.
Gas welding and Thermit welding are usually reserved for specific specialized applications (like earthing busbars) and are not standard for insulated power cables due to the risk of thermal damage to cable insulation.
C is correct тАФ Compression is the standard mechanical method for creating reliable, low-resistance connections in aluminum power cables by inducing plastic deformation.
Always remember that for electrical connections involving aluminum, the primary constraint is the rapid re-formation of the resistive oxide film; compression is designed specifically to overcome this physically.