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The methods used for joining of copper conductor cables and aluminum conductor cables are
Thermit welding
Soldering
Compression
Both (b) and (c)
Both (b) and (c)
Joining copper to aluminum conductors requires specialized techniques to prevent bimetallic corrosion (galvanic action) and to account for the differences in thermal expansion coefficients and surface oxide layer formation. Both soldering with special fluxes and compression joints using inhibited compounds are standard industrial methods for these dissimilar metal connections.
Joining copper to aluminum conductors requires specialized techniques to prevent bimetallic corrosion (galvanic action) and to account for the differences in thermal expansion coefficients and surface oxide layer formation. Both soldering with special fluxes and compression joints using inhibited compounds are standard industrial methods for these dissimilar metal connections.
R=╧БALтАЛ тАФ Resistance of conductor governing heating at the joint
IthтАЛ=RтЛЕtHтАЛтАЛ тАФ Current capacity based on thermal limits of the joint
In compression joints, a mechanical crimping tool applies high pressure to create a gas-tight bond, while an oxide-inhibiting compound prevents the reformation of aluminum oxide (Al2тАЛO3тАЛ). Soldering requires specific fluxes capable of dissolving the tough aluminum oxide layer to ensure the tin-lead or silver solder alloy adheres to both metals, creating a continuous electrical path.
Galvanic corrosion occurs when copper and aluminum are in contact in the presence of moisture.
Bimetallic connectors or 'Bi-metal lugs' are frequently used for joining aluminum to copper.
Aluminum oxide is an insulator that must be removed via flux or mechanical abrasion during jointing.
Compression joints rely on physical deformation to maintain high contact pressure.
Compression joints provide high mechanical strength.
Soldering provides excellent contact surface area in low-current environments.
Copper and aluminum have different coefficients of thermal expansion.
Galvanic action can lead to increased contact resistance over time.
Power distribution cable terminations.
Service entrance cable connections.
Busbar to cable transitions.
Thermit welding is primarily used for grounding connections (copper to copper or copper to steel) and is unsuitable for general-purpose aluminum-to-copper power cable joining due to the extreme heat affecting aluminum's mechanical properties.
Compression joints are preferred for high-voltage power cables due to reliability.
D is correct тАФ Both soldering and compression are effective methods for joining dissimilar copper and aluminum conductors when appropriate inhibitors or fluxes are utilized to prevent galvanic corrosion.
In competitive exams, remember that thermit welding is for 'Exothermic Welding' used for permanent earthing connections, not for delicate dissimilar metal power cable splicing.