Select conductor type according to the development of load and the requirement of transmission capacity under the condition of N-1.

For the transformation of transmission lines, the selection of heat-resistant conductor type must be based on the development of load and N-1 transmission capacity requirements. Utilizing the characteristics of high transmission capacity of heat-resisting wire, the line has the ability to transmit a certain reserve capacity, so as to meet the demand of load development and transmission capacity under N-1 and other abnormal operation modes, and increase the reliability of power grid.

Selection of heat-resistant conductor type must be combined with selection of conductor cross section.

Conductors with different heat resistance have different current carrying capacity, so the size of cross section should be considered when selecting the type of conductor. The heat resistance and cross-sectional area of the conductor directly affect the cost of the transmission line, and also affect the proportion of line loss. The line loss of the conductor with different heat resistance at the same section increases with the increase of the permitted operating temperature.

The selected heat-resistant conductor must meet the requirements of sag change.

Different heat resistant wires have their sag characteristics. When using the tower of the original line, the sag of the heat-resistant conductor increases with the increase of temperature, so as to meet the requirements of the conductor distance to the ground and crossing.