Transposition of Conductors refers to the exchanging of position of conductors of a three phase system along the transmission distance in  such a manner that each conductors occupies the original position of every other conductor over an equal distance. 

          When conductors are not transposed at regular intervals, the inductance and capacitance of the conductors will not be equal.

              When conductors such as telephone lines are run in parallel to transmission lines, there is a possibility of high voltages induced in the telephone lines.  This can result in acoustic shock or noise.  Transposition greatly reduces this undesired phenomenon.  

            In practice, however, conductors are not transposed in the transmission lines.  The transposition is done in the switching stations and the substations.