Alternator and its Components

Alternator:

The synchronous generator is an alternating-current machine, without rings or brushes.  Alternator comprises of rotating field and stationary three phase armature

Alternator Parts And  Functioning

Alternator Frame: Provides the structural strength and rigidity for the generator and serves as a housing to guide cooling air flow.

Inner End Shield: Is a baffle used to form a path for cooled air.

Generator Fan: Provides continuous circulation of cooling air.

Rotating Field: A magnetic field which induces AC voltage in the stator windings.

Collector Rings: Provide a connection and path for DC power into the rotating field windings.

Main Coupling: Is the connection to the drive shaft

Generator Coolers: Remove heat from the generator cooling air.

Stator Core: Houses the stationary windings and forms a magnetic path necessary for induced voltages

Air Gap: Is the radial clearance between the rotating field and the stator core

Exciter:

The excitation system is mounted on the side opposite the coupling. The excitation system comprises two assemblies:

The excitation armature, generating a three-phase current, coupled with the three-phase rectifier bridge (comprised of

six diodes) supplies the excitation current to the generator revolving field. The excitation armature and the rectifier bridge are mounted on the synchronous generator rotor shaft and are interconnected electrically with the revolving field of the machine.

There are three types of Exciters:

Brushless: do not require slip-rings, commutators, brushes and are practically maintenance free.

Brush Type: require slip-rings, commutators and brushes and require periodic maintenance.

STATIC EXCITERS

Static excitation means no moving parts. It provides faster transient response than rotary exciters

Shunt Type: operating field power from generator output voltage.

Series Type: operating field power from generator output voltage & current.