Determination of unbalance of untransposed lines

DURING THE EARLY YEARS of the electrical industry it was found that transmission-line transpositions were essential in order to reduce undesirable communication circuit interference. This was due largely to the extreme susceptibility of early communication circuits to both 60-cycle and harmonic frequency disturbance. However, developments in communication practice have reduced greatly this justification for power-line transposition, such as the use of underground or otherwise shielded circuits and separate rights of way.