Two-Phase Machines and Four-Phase Power

• 3 phase supplies all that is needed for smooth power transmission between generator and user, for the minimum amount of conductor material.
• 3 phase tansforms easily to 3 x single phase by introducing an earth connection at the star point of the local distribution transformer.
• Everybody's doing it.

i know tht 3phase supply is very common

i just wana knw whether other phases exixts and if yes y arent thy are in so much of use...

• 3 phase supplies all that is needed for smooth power transmission between generator and user, for the minimum amount of conductor material.
• 3 phase tansforms easily to 3 x single phase by introducing an earth connection at the star point of the local distribution transformer.

One of the main use of electricity, besides lighting, is to convert electrical energy to mechanical energy. That is mostly done by motors.

Even number of phases cancel each paired phases out because because they are 180 degrees apart, equal in magnitude but opposite in 'direction'. Thus they are unable to create a differentiated magnetic rotating field. The smallest number of odd phases is three, hence it's popularity:-).

In a two phase system, the voltages are 90 degrees out of phase, not 180. A simple motor arrangement of four poles, connected to either two phase 3W (common neutral) or 2 phase 4W system produces the rotating magnetic field necessary for the motor's operation. See http://www.tpub.com/content/neets/14177/css/14177_88.htm

look at http://www.3phasepower.org/2phasesystems.htm. This should answer your question.

thanks a lot for that site

Although i have never worked on polyphase machines i believe that some industrial power tool manufacturers make tools with their own inverter power supplies that work on a multiphase system.