It is known that the electric supply used, now a days for commercial as well as domestic purposes, is of alternating type.
Similar to d.c. machines, the a.c. machines associated with
alternating voltages, are also classified as generators and motors.
The machines generating a.c. e.m.f. are called alternators or
synchronous generators. While the machine accepting input from a.c.
supply to produce mechanical output are called synchronous motors. Both
these machines work at a specific constant speed called synchronous
speed and hence in general called synchronous machines.
All the modern power stations consists of large capacity three
phase alternators. In this chapter, the construction, working principle
and the e.m.f. equation of three phase alternator is discussed.
