Two Phase

The two phase electric power system was actually used during twentieth century. It is a polyphase AC electrical power supply system.  The two phase or circuit system were utilized with the voltage phases varying by 90 degrees.  Generally this system utilized four wires i.e. two for every phase.  Sometimes three wires were also used with a common with a bigger diameter conductor.  A few of the early two circuit motors featured with two complete field and rotor assemblies with windings actually offset by 90 electric degrees  in order to offer  two-phase current or power.  In the year 1895, the two two-phase machines or generators were installed at the Niagara Falls, which were actually considered to be the largest generators in the world.  The main advantages of the two-phase generators were it enabled for easy self-starting electric generators or motors. In early days of the electrical engineering, it was quite easy and simple to design and analyze the two phase power   system where the phases were totally separated.  

 It was not until the creation of the method of the symmetrical components in the year 1918 that the polyphase electrical systems had the suitable mathematical tool for describing the unbalanced load cases. The two-phase  electrical power system, produced  the revolving magnetic field which allowed  the electric motors or generators to offer torque from zero "0" motor speed that was not possible with the single-phase  electrical induction motor i.e. without any additional starting means.  The induction motors w designed for the two-phase function actually uses the same winding feature like the single-phase capacitor start motors. The three phase electrical power needs less conductor mass for providing the overall amount of current and voltage, when compared with the two-phase four-wire  power system of the same carrying power.

Questionnaire:

• What is two phase electric power system? Explain.