Generator

GENERATOR (Alternator)Converts mechanical energy into

electrical energy.

3 Elements Required

to produce a VOLTAGE

Conductor

Magnetic Field

Relative motion between conductor and magnetic field

VOLTAGE INDUCED

N St

HOW CURRENT AND VOLTAGE IS INDUCED

a

b

c

a

c

phase

b

i

Major Components of an

AC GENERATOR

Stator

Stationary Part

Armature Winding

Where the output current and voltage is produced. It can be mounted either on the rotor or stator.

Rotor

Revolving Part driven by Prime Mover

Field Winding

Magnetic Field Component mounted on either rotor or stator

Exciter

Supplies excitation voltage to the field winding

Exciter

Rotor

Stator

Armature Winding

Field Winding

THE EXCITATION SYSTEM

ExcitationThe process of generating a magnetic field by means of direct current.

TRANSFORMERAND RECTIFIER

DC

AC

STARTUP GENERATORSTATIC EXCITATION

GENERATOR VOLTAGE REGULATION

Voltage is regulated by adjusting the strength of the magnetic field around the generator rotor.

EXCITER

AVR

DC

AC

If generator load decreases, voltage increases

decrease exciter currentvoltage returns to normal

EXCITER

AVR

DC

AC

If generator load increases, voltage decreases

increase exciter currentvoltage returns to normal

Synchronization

Putting the generator online by matching the generators frequency and voltage to the grid without interruption.

Same Terminal Voltage. incoming generator voltage bus-bar voltage.

Same Frequency. incoming generator frequency bus-bar frequency

Same phase sequence. phase sequence of the 3 phases of the incoming generator same as that of the bus bars.

Synchronizing Panel

GENERATOR BUS VOLTAGE/FREQUENCY

GRID BUS VOLTAGE/FREQUENCY

SYNCHRO CHECK RELAY