The Sag and Fatigue Properties of STACIR/AW as a High Temperature, Low Sag Conductor

In Korea, as a way to expand electric capacity in power line with increasing of electric power demand, the STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) conductor are used. The STACIR/AW consists of stranded INVAR/AW wire as core material for sag control and heat-resistant Al alloy for ampacity gain which was developed to catch up with tremendous increase of electric power demand. These two different materials enable the STACIR/AW to operate at a higher temperature compared to a conventional ACSR (Al alloy Conductors Steel Reinforced) without modifications to the tower. It is generally accepted that the continuous operating temperature of STACIR/AW is 210degC which is remarkably high compared to that of ACSR, 9degC. But some case of 480 mm² STACIR/AW (conductor named Rail) of the commercial line, there are some problems with regard to sag characteristics. This paper describes the results from a long term maximum permissible current characteristic experiment using full scale test line which is energized up to 3000 A. Also the variation of fatigue property with heat exposure in stranded conditions will be presented.