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The conductors of the overhead lines are
Stranded conductors
Solid conductors
Bundle conductors
None of the above
Stranded conductors
Overhead transmission lines typically use stranded conductors to ensure mechanical flexibility and prevent breakage under wind pressure or vibration. A stranded conductor consists of a central wire surrounded by successive layers of helical wires, which allows the line to bend without fatigue during installation and operation.
Overhead transmission lines typically use stranded conductors to ensure mechanical flexibility and prevent breakage under wind pressure or vibration. A stranded conductor consists of a central wire surrounded by successive layers of helical wires, which allows the line to bend without fatigue during installation and operation.
N=3n2тИТ3n+1 тАФ where N is the total number of strands and n is the number of layers.
Stranding increases the overall flexibility of the conductor compared to a single solid wire. By twisting multiple thinner strands together, the conductor can withstand thermal expansion, contraction, and mechanical vibrations (like Aeolian vibration) more effectively, preventing crystalline fatigue failure that would occur in a stiff solid conductor.
Stranded conductors provide higher flexibility than solid conductors.
Easier to manufacture, transport, and install over long distances.
Skin effect is slightly mitigated as the effective cross-section is composed of multiple smaller wires.
Commonly used material is ACSR (Aluminum Conductor Steel Reinforced) for higher tensile strength.
Higher mechanical flexibility
Less prone to fatigue failure due to vibration
Easier handling and spooling during line construction
Higher complexity in manufacturing
Slightly higher cost than solid wires of equivalent section
Requires compression joints for splicing
High Voltage Overhead Transmission lines
Distribution networks
Industrial power cabling
Solid conductors are restricted to very small gauges (like house wiring) where current is low and flexibility is not critical.
Bundle conductors (Option C) refer to using multiple conductors per phase to reduce corona loss and reactance, but these bundles are themselves made of stranded conductors.
A is correct тАФ Stranded conductors are used in overhead lines to provide necessary mechanical flexibility and endurance against vibrations.
In competitive exams, remember that ACSR is a type of stranded conductor used specifically for long-span transmission to balance conductivity (Aluminum) and tensile strength (Steel core).