What happens to transmission lines that are not transposed?

When transmission lines are not transposed, they do not experience balanced loading among the three phases. Transposition involves periodically switching the positions of the conductors across the phases to ensure that each conductor experiences the same electrical and magnetic environment. If the lines are not transposed, it leads to uneven line impedance and can cause one phase to carry more current than the others. This results in the lines behaving more like a single-phase system rather than a balanced three-phase system. Such an imbalance can lead to issues such as increased losses, voltage imbalances, and potential overloading on certain phases, ultimately affecting the efficiency and stability of the transmission system.