CALCULATION OF MINLMUM INSULATION CLEARANCES OF 132 KV THREE PHASE TRANSMISSLON LINES FOR CONVERTING TO SiX PHASE LINES

One of the previous methods for increasing the capacity of transmission lines is uprating its voltage to higher level of voltages. In this method both phase to neutral voltage and phase to phase voltage increased and therefore , it is necessary to improve and increase the insulabon clearances of conductors.in 19720e method of converting the double circuit three phase lines to single circuit six phase lines was offered for this purpose with better capabiiities. In this paper the authors offer some constraints about phase insulation clearances of 132 KV double circuit three phase transmission lines for converting these lines to 132 KV single circuit six phase lines with considering minimum variations in configuration of tower and conductors of double circuit lines. In this way, they use standard limitation of clearances of Naflonal Electrical Safety Codes [N.E.S.C) as a reference and produce four constraints for this purpose. Then they test these constraints for an existing line in Khorasan transmission network and check it for ability of converting to a single circuit line.