Introduction  In order to increase the capacity of a 220 kV transmission line, conventional conductor and various heat-resistant conductors are selected to make comprehensive comparison.

  Method  This article calculated the maximum operating temperature and power loss, compared effects of mechanical load and wire sag variation on tower foundation, analyzed difficulty of construction and maintenance, and calculated investment and annual cost.

  Result  The results show that all selected conductors can meet the need of increasing capacity and maximum operating temperature; towers and foundations need rebuilding if using conventional conductor; mechanical load and wire sag of heat-resistant conductors meet the design conditions of original transmission line; conventional conductor and Aluminum Conductor Multi-strand Carbon Fiber Core (ACMCC Conductor) have lower annual costs and more convenience for maintenance.

  Conclusion  Our work shows that ACMCC Conductor has excellent comprehensive performance and is suitable for enhancing transmission capability of transmission lines in operation without rebuilding, especially in urban or suburban areas where it is difficult to build new towers.