AC generator (Alternator) – Three phase
A single-phase a.c. generator or alternator has only one armature winding. If a number of armature windings are used in the alternator it is known as polyphase alternator. It produces voltage waves equal to the number of windings or phases. Thus a polyphase system consists of a numerous windings which are placed on the same axis but displaced from one another by equal angle which depends on the number of phases. Three-phase alternators are widely preferred for transmitting large amount of power with less cost and high efficiency.