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.
Yes, it is possible to have a more than 3-phase system. In fact, there are systems with 4, 5, 6, and even up to 12 phases.
Having more than 3 phases allows for a more balanced distribution of power, which results in lower transmission losses and increased efficiency. It also allows for the use of smaller and more cost-effective equipment.
The number of phases needed in a system depends on various factors such as the amount of power required, the distance of transmission, and the type of load. A thorough analysis of these factors is needed to determine the optimal number of phases for a specific system.
One limitation is that the equipment and infrastructure needed for a more than 3-phase system can be more complex and expensive. Additionally, the higher number of phases may also require stricter power quality control measures.
It is possible to use a more than 3-phase system in residential areas, but it is not common. These systems are typically used in industrial or commercial settings where higher power demands are required. In residential areas, the standard is a 3-phase system.