Vector Diagram of a Loaded Three Phase Alternator

a. Unity Power Factor

Construction of Alternator

1. STATOR –It is build up with stamping which are insulated with proper varnish. The stator is house in a frame which is fabricated from electricity welded steel plates.
2. ROTOR – Has the rotating magnetic field poles as in DC generator which is separately exited from source known as exciter.

General Types of Alternator

A. SYNCHRONOUS GENERATOR
A generator called synchronous because it is driven at constant speed (synchromous speed) and it is used in almost all type of application.

B. INDUCTION GENERATOR
It is an induction motor which run as generator with speed above synchronous speed. Its pf is usually leading and connected in parallel with a synchronous generator in order to supply power.

C. INDUCTION ALTERNATOR
It generates voltage at higher frequency (500 hertz to 10,000 hertz) it is used to supply power to induction furnace in order to hit and melt the metal.

ALTERNATOR (AC GENERATOR)

Is an electric machine that converts machine energy to electric energy in the form of alternating current?
An alternator is exactly the same as that dc generator. In fact all the generators alternators is which alternating voltages are set-up and it is the commutator which converts this ac into dc.
In the dc generator, it is essential for the armature to rotate in the magnetic field produced by the stationary magnetic field to give the unidirectional voltage. However in alternator it is not essential for the armature to rotate and either the armature or field can be made to rotate while the other is kept constant. But nowadays, armature is kept stationary and the field rotates under it.