138-kV, Six-Phase Transmission System: Fault Analysis

In the past decade, transmission planners and researchers have been keenly investigating the feasibility of six-phase concept as a planning alternative. The concept, if proved feasible, would alleviate the problem of acquiring additional rights-of-way to meet the increase in electric power and energy demand. Allegheny Power System (APS) has been investigating the conversion of some of their 138-kV three-phase double- circuit lines to 138-kV six-phase lines. The latter is an alternate option to 230-kV three-phase upgrading of the line.