What is a 3 phase generator?

It is an electric generator driven by a rotating shaft that generated electric power in three-phase form. The other name for one of these is an alternator.

Alternators are used almost exclusively to generate electric power in power plants across the world. The power is then transformed to appropriate voltage levels on its way to the consumers.

An alternator has a set of three pairs of fixed coils on the stator, and a single coil fed with direct current through slip rings on the rotor.

Alternators are also used to generate electric power in cars. In this case the power is fed through a full-wave rectifier using six diodes to connect the power directly to the car battery. The voltage is controlled by an integral device attached to the alternator that controls the current fed to the rotor. Current for this is taken from a half-wave rectifier using another three diodes, and it is passed through the ignition switch.