Editing Electric power transmission (section)

=== Transposition ===
{{Unreferenced section|date=November 2022}}
Current flowing through transmission lines induces a [[magnetic field]] that surrounds the lines of each phase and affects the [[inductance]] of the surrounding conductors of other phases. The conductors' mutual inductance is partially dependent on the physical orientation of the lines with respect to each other. Three-phase lines are conventionally strung with phases separated vertically. The mutual inductance seen by a conductor of the phase in the middle of the other two phases is different from the inductance seen on the top/bottom.

Unbalanced inductance among the three conductors is problematic because it may force the middle line to carry a disproportionate amount of the total power transmitted. Similarly, an unbalanced load may occur if one line is consistently closest to the ground and operates at a lower impedance. Because of this phenomenon, conductors must be periodically transposed along the line so that each phase sees equal time in each relative position to balance out the mutual inductance seen by all three phases. To accomplish this, line position is swapped at specially designed [[transposition tower]]s at regular intervals along the line using various [[Transposition (telecommunications)|transposition schemes]].