Abstract
Circular, plate, radial and coaxial arrangements for phases of double circuit transmission lines are proposed. Power transmission over long distances depends on the mutual effect between each two respective phases. A theoretical analysis for voltage, power and current along such lines is presented. The general constants for each configuration are evaluated, as well as the maximum power limit for long distance double circuit transmission lines. Different voltage levels of 500 and 1000 kV are considered for a length of 1000 km. An external impedance is suggested to be connected at various points of coaxial arrangement with separate phases. The capacitive effect for such an external impedance is studied.