Higher phase numbers than three are not only theoretically possible but have been practically implemented in various applications. Six-phase systems, commonly used in rectifier installations and HVDC converters, utilize 60-degree phase spacing to minimize harmonic generation and ensure smoother direct current. Additionally, experimental high-phase-order transmission lines have been constructed with up to 12 phases, allowing for enhanced power transfer while adhering to Extra High Voltage (EHV) design rules. Techniques such as delta-wye and zig-zag transformers are employed to achieve necessary phase displacements in these systems.
PREREQUISITESElectrical engineers, power system designers, and professionals involved in high voltage and rectifier technology will benefit from this discussion.
Higher phase numbers than three have been used. A common practice for rectifier installations and in HVDC converters is to provide six phases, with 60 degree phase spacing, to reduce harmonic generation in the AC supply system and to provide smoother direct current. Experimental high-phase-order transmission lines have been built with up to 12 phases. These allow application of Extra High Voltage (EHV) design rules at lower voltages, and would permit increased power transfer in the same transmission line corridor width.