This document provides an overview of generators, including their principle of operation, history, and types. It discusses how generators work by converting mechanical energy to electrical energy using electromagnetic induction. The history outlines early electrostatic generators and the invention of dynamos and alternators. There are two main types of generators - AC and DC generators - with AC generators being most commonly used in power systems today. Synchronous and induction generators are types of AC generators that are further described.

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3. Context:
• Introduction to Generators.
• Principle of working.
• History of Generators.
• Types of Generators.

4. Introduction to Generators
• The device which converts mechanical energy
to electrical energy is called generator
MEHANICAL ENERGY GENERATOR ELECTRICAL ENERGY

5. Principle of working:
• In generators mechanical energy is
transformed into electrical energy.
• The principle of all of the generators is same,
although the detail of construction may be
differ somewhat.
• A generator has two main parts:
• Coil
• Magnet

6. Principle of working:
Generator works on
Faraday’s law of
electromagnetic
induction. When coil is
rotated in a magnetic
field by some mechanical
means magnetic flux is
changed through the coil
and consequently EMF is
induced in the coil.

7. History and evolution of Generators
• Michel Faraday and Hippolyte Pixii were
pioneers who invented early machines like
generator. There are following stages of
evolution of Generators.
• Electrostatic generators.
• Principle of electromagnetic induction.
• Invention of Dynamos.
• Alternators and their evolution.

8. Electrostatic Generators:
• Before the connection
between electricity and
magnetism was
discovered Electrostatic
generators were
invented.
• They were never used
for commercial power
generation and were
left due to inefficiency
and difficulty.

9. • An electrostatic
generator is
an electromechanical
generator that
produces static
electricity, or
electricity at high
voltage and
low continuous
current.

10. Dynamos:
• Dynamos use
electromagnetic
principles to convert
mechanical rotation
into a pulsating direct
electric current through
use of a commutator.
• 1st dynamo was built by
Hippolyte pixii in 1832.

11. Alternators:
• Dynamos were succeeded
by alternators which was
capable of generating ac.
• 1st TWO PHASE AC
GENERATOR was built by
J.E.Gordon in 1882.
• Nikola Tesla, Lord Kelvin
and Sebastian Ferranti did
very useful work in
evolution of alternators.

12. Types of Generators:
• According to output generators are of two
types AC generators and DC generators.
• According to output generators are of two AC
generators and DC generators.

13. DC Generator system
• They are generally used when the distribution
network is small and power required is low
(below 2KW).
• Can be used only when the load is close to the
generator.

14. Advantage
• It doesn't require a governor and load
controller, so the price can be greatly reduced.
• Storage batteries may be charged during
excess generation to provide for peek loads.

15. AC Generator system
• Most preferred & conventionally used in all
power systems.
• Can be singe phase or three phase
• Single phase is preferred at low ratings and
three phase is preferred at higher ratings.

16. Advantage:
• Cheaper
• More reliable
• Maintenance is easy
• Profitable

17. AC Generators are classified into:-
• Synchronous generator
• Induction generator

18. Synchronous Generator
• It has the ability to control the power factor ,so
the overall power factor can be improved.
• It gives constant speed from no load to full load.
• Higher efficiency
• Lower running and maintenance cost.
• It is a doubly excited machine. The field winding
that is rotor is excited using DC source and its
stator that is armature winding is excited using
AC source.

19. Contd…
• Starting from its name ‘synchronous’, this gen
runs at synchronous speed whatever the
amount of load it may be.
• it doesn't have self starting torque, so some
other auxiliary means have to be provided for
starting the synchronous machine.
• much costlier that a similar rating induction
gen.

20. Advantage
• Ability to control the power factor.
• Speed remains constant irrespective of variation
in loads.
• It can be constructed with wider air gaps than
induction motors which makes these motors
mechanically more stable.
• usually operate with higher efficiencies ( more
than 90%)

21. Disadvantage
• It cannot be used for a variable speed job.
• It requires separate dc excitation.
• It cannot be started under loaded condition.
• May stop when overloaded
• Brushes are required

22. Application
• Used in power house and sub stations
• They’re employed to improve the power
factor
• Used in controlling the voltage at the end of
the transmission line
• Used in factories requiring constant speed

23. Induction generator
• The speed of induction motor is always less
than the synchronous speed and it is
dependent on the load since the speed
decreases with the increase in load.
• It is a singly excited machine where its stator
windings are excited using an AC source.
Contrary to the case of synchronous motor,
induction motor works only under lagging
power factor.

24. Contd…
• It is comparatively less efficient.
• The cost of induction machine is less when
compared with a synchronous motor of same
rating.
• This kind of motor has its own self starting
torque.

25. Advantage
• Simple & robust construction
• Inexpensive
• Durability
• Has inherent overload protection
• More suitable for high speeds
• Doesn’t require commutator brush
arrangement .

26. Disadvantage
• Smaller generator cost more per kilowatt to
build
• High initial cost
• Must run parallel with synchronous machine

27. Applications
Because of distinct superiority of synchronous
generator induction generators are rarely used
to supply commercial power.
They are used in braking purpose of railway.

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