138 kV 12-phase as an alternative to 345 kV 3-phase

The results are presented of an experimental and analytical program which included construction of a 12-phase steel lattice portal tower with special insulators, construction of a 12-phase substation, and subsequent energization of the first 12-phase power transmission line. Impedances, electrical environmental effects (radio noise, audible noise, and electric fields) are among the parameters measured and evaluated. This 12-phase design is compared with several existing 345-kV three-phase lines for thermal and surge impedance loading, electrical environmental effects and physical size requirements. The 12-phase design offers comparable loading in less space with reduced electrical environmental impact. This is illustrative of the possibilities of high phase order as a replacement for three-phase at other voltage levels.<<ETX>>