In this presentation, we see the concept of alternator, Excitation system , Different types of Excitation system such as DC Excitation system, AC Excitation system with block diagram, advantages, disadvantages and static excitation system, then we reach at our final conclusion.
4. 1. It is an electrical machine which
converts mechanical power into
electrical power by the principle of
Electro-magnetic induction.
2. Alternators are the primary source of
all the electrical energy .
6. 1. The process of creating and
strenthening the magnetic field of the
alternator by providing the necessary
direct current to the field winding of the
alternator.
2. The direct current is supplied to the
rotor by a separate DC source called
as Exciter.
7.
8. Function Of Excitation System
1.Supply direct current to the field
winding for creating magnetic field.
2. Control Voltage.
3. Control Reactive Power.
4. Perform Protective Function.
9. TYPES OF EXCITATION
SYSTEM
1.DC Excitation System
2. AC Excitation System
1.Brushless Excitation System
2. Rotating Thyristor Excitation
System
3. Static Excitation System
11. 1. The DC excitation system has two
exciters
a. Main Exciter
b. Pilot Exciter
2. The exciter output is adjusted by an
automatic voltage regulator for
controlling the output terminal voltage
of the alternator.
3. The voltage rating of the main exciter
is about 400V.
12. ADVANTAGES:
1. It is more reliable
2. It is compact in size
3. It can be brought anywhere due to its
low weight.
15. 1. It consist of AC generator and
Thyristor rectifier bridge directly
connected to the alternator shaft or
driven by separate motor.
A. Brushless Excitation System
1. Main exciter is separately excited.
B. Rotating Thyristor Excitation System
1. Main excxiter is self excited.
20. ROTATING THYRISTOR TYPE
EXCITATION SYSTEM
1. This system consists an AC exciter,
stationary field and a rotating armature.
2. The output of the exciter is rectified
by a full wave thyristor bridge rectifier
circuit and is supplied to the main
alternator field winding.
22. STATIC EXCITATION SYSTEM
1. There is no rotating part in static
excitation system.
2. So no windage loss.
3. Small size.
23. CONCLUSION:
Selection of excitation system depends
on various factors:
1. Alternator Power
2. Alternator Size
3. Alternator Speed
4. Maintenance Cost