SOLUTION

Bundle Conductor: If two or more conductors per phase are bound together with connecting wires, a bundle conductor is formed. In each phase, two sub conductors are separated from each other by 30 cm or more. Thus, the overall diameter of the bundle conductor is increased. They are widely used for the transmission of large power over long distances to reduce corona loss.

Advantage of  Bundled Conductors

By using bundled conductor the self GMD of the conductor is increased

Corona Loss ∝ (V – V_o)²   

Where V = R.M.S phase voltage 

V_o = Disruptive critical Voltage

V_o is approximately directly proportional to the size of the conductor, therefore, the larger the size of the conductor larger the disruptive critical voltage, and the smaller will be the factor of (V – V_o)^2, and hence smaller will be the corona loss.

• Bundling of conductors leads to a reduction in line inductance.
• The bundling of conductors leads to increases in capacitance.
• An important advantage of bundled conductors is their ability to reduce corona discharge
• Reduction in the formation of corona discharge leads to less power loss and hence improved transmission efficiency of the line.
• Reduction in communication line interference.
• Per phase line inductance and per phase capacitance are reduced.
• It increases the surge impedance loading.
• A large amount of power can be transmitted.
• It produces less corona loss.

Disadvantages of Bundle conductor

Because of the large cross-sectional area, the wind and ice-loading effects are more.

Due to the large cross-sectional area, clearance between structures is required more. It increases the higher charging kVA.