Transposition of Conductors

Definition: The process of transposition involves physically rotating the conductors in a regular sequence. The transposition balances the mutual inductance and capacitance between the lines. The spacing between conductors is irregular, resulting in complex inductances that complicate the study of power systems. Transposition is a process that usually takes place at switching stations and substations. The figure below illustrates the conductors’ transposition cycle.


Needs of Transposition of Conductors

When an electrical transmission line is unsymmetrical, it can have inductance, leading to voltage drops even when the voltage is balanced. This occurs because the magnetic field exists within the conductor due to the inducing voltages, which causes interference in the line.

The inductance of an unsymmetrical line is caused by the unequal placement of the conductors in the line. This, in turn, leads to variations in the magnetic field generated by the current flowing through the conductors. To minimize this interference, we can continuously exchange the position of the conductor, which can be achieved by transpositioning the conductors.

In conductor transposition, the conductors are physically moved so that each conductor takes the position of the adjacent one. Thus, the previously closest conductor to the ground may now be positioned closer to the other conductor. This continuous exchange of the positions of the conductors reduces the variation in the magnetic field and minimizes the interference.

Transposition Method

To maintain the voltage balance on a power line, it is crucial to balance the capacitance of the line. This can be done by transposing the lines, which means placing the one-third segment of all three conductor phases in the same line. This technique helps to reduce voltage imbalances on the line, making it more efficient and effective.

Disadvantage of Transposition of Conductors

Frequently moving the conductors from their original position can lead to a weaker supporting structure, which eventually results in higher system costs.


In conclusion, a crucial aspect of optimizing the efficiency and safety of electrical systems is understanding the process of conductor transposition. Proper transposition techniques can mitigate electromagnetic interference and ensure a balanced voltage distribution.

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