Voltage Induction in Parallel Transmission Circuits

General formulas are developed with calculation examples for determining the positive-, negative-, and zero-sequence voltage induced in transmission circuits paralleled either on the same tower or on adjacent towers. For nontransposed lines the induced voltages are a function of all three sequence currents. The positive-and negative-sequence mutual impedance is less than 10% of the self-impedance of the lines while the zero-sequence mutual impedance can be as high as 50 to 70% of the zero-sequence self-impedance of the lines. The conductor configuration should be symmetrical around a vertical axis to avoid differences in the induced voltages in the two circuits.