Heidari - Scientific Societies Dept. Tavanir - IRAN

In recent years, the conductors diameters in different classes of transmission fines have increased, as such that, drake (795 KCM) conductors are used in 132 KV lines & curlew (1033 KCM) conductors in 230 KV transmission fines. It is obvious that, by increasing the conductors diameters, while decreasing the fine losses, the Investment on transmission line will increase, on the other hand, although the voltage drop & fine stability are direct dependent of resistance, capacitance & reactance of fine conductors but, in practice their dependancy on conductor diameter are weak ( in normal condition up to 5 per cent) hence, from Techno-Economical point of view it is not always justifiable to increase the conductor diameter to fulfill the conditions required for increasing power rating of fines or improving the line stability In this paper by finding a Techno-Economically acceptable answare to this question of : a thick conductor or several conductors with equivalent Cross-Secdon, it is shown that, when increasing the cross rection of line becomes necessary, up to a certain limit, imcressing the conductor's diameter is plusible , above that limit it should be replaced by several sub conductors with equivalent Cross-Section in each phase. In other words what we are to find out in this paper, is to see wheather 1xs is better or K x S/K