Rhythm Sharma

CERTIFICATE
It is to certify that RHYTHM

SHARMA of class XII-A, S.D.
Model Sen. Sec. School has
completed his project file
under my supervision.
He has taken proper care and
shown utmost sincerity in
completion of this project.
I certify that his project is
upto my expectations as per
the guidelines issued by
C.B.S.E.
MRS. ANSHU GUPTA

ACKNOWLEDMENT
I would like to express my
special thanks of gratitude
towards my teacher Mrs.
ANSHU GUPTA who gave me
the golden opportunity to do
this wonderful project on the
topic AC GENERATOR, while
working on this project I came
to know about so many new
things and helped me a lot in
finalizing this project within the
limited time frame.
• INTRODUCTION
• CONSTRUCTION
• WORKING
• EFFICIENCY
• USES OF GENERATOR
• BENEFITS
• CONCLUSION
AC generators are electric generators
that convert/change mechanical energy
to electrical energy in an alternating EMF
or alternating current. In AC generators
the supply of input is a mechanical
energy switch supplied through
combustion engines, gas turbines, and
steam turbines. The generated output is
alternating electrical power in the form of
current and alternating voltage.
The working principle of the AC
generator is based on Faraday’s Law of
electromagnetic induction. The law states
that the current will be induced in the
conductor when placed in the magnetic
field.
• The strong magnetic field is produced by a
current flow through the field coil of the
rotor.
• The field coil in the rotor receives
excitation through the use of slip rings and
brushes.
• Two brushes are spring-held in contact
with the slip rings to provide the continuous
connection between the field coil and
the external excitation circuit.
• The armature is contained within the
windings of the stator and is connected to
the output.
• Each time the rotor makes one complete
revolution, one complete cycle of AC
is developed.
• A generator has many turns of wire wound
into the slots of the rotor.
• The magnitude of AC voltage generated by
an AC generator is dependent on the field
strength and speed of the rotor.
• Most generators are operated at a constant
speed; therefore, the generated voltage
depends on field excitation, or strength.
An AC generator works on the principle of
electromagnetic induction. In
electromagnetic induction, an electric
current or EMF is induced in the coil when
there is a relative motion between a coil and
a magnetic field.
The magnetic flux associated with an
armature changes continually as it rotates
between the poles of the field magnet. As a
result, the armature generates an EMF. As a
result, an electric current flows through the
armature and galvanometer, and the slip
rings and brushes note that the
galvanometer needle swings between
negative and positive values, indicating that
the galvanometer is receiving alternating
current (AC).
Expression for Instantaneous e.m.f.
Produced:
Let position of the coil at any time t. It
make angle q with vertical.
If w is uniform angular speed of the coil.
Then q = wt
B be the strength of magnetic field n be the
number of turns in the coil and A area of
the coil then magnetic flux with the coil in
this position is given by:
f = nBA Cos q
= nBA Cos wt
Differentiate w.r.t. time
= nBA (-Sin wt) w
= -nBA w Sin wt
e = - (-nBA w Sin wt)
Maximum value of e.m.f. say ε0
e = ε0Sin wt
• Efficiency of an AC generator is the ratio
of the useful power output to the
total power input.
• Because any mechanical process
experiences some losses, no AC
generators can be 100 percent efficient.
• Efficiency of an AC generator can
be calculated using equation: Efficiency
=(Output /Input )x 100
.
• Aircraft auxiliary power generation,
wind generators, high speed gas
turbine generators.
• Hybrid electric vehicle (HEV) drive
systems, automotive starter
generators.
• An ac generator, or 'alternator', is u
sed to produce AC voltages for
transmission via the grid system or,
locally, as portable generators.
• All of our household appliances run
s on AC current.
• Ex: Refrigerator, washing machines,
oven, lights, fan etc.
• AC generators have numerous benefits
over DC generators. Some significant
advantage of AC generator over DC
generator is as follows:-
• The AC is simpler to generate than DC.
AC is more cost-efficient than DC
• In AC generators, during the generation
of Power, energy wastage is almost
negligible.
• The Size of the AC generator is smaller
as compared to DC.
• AC is easy to step up and step down
through the transformer.
• Transmission link size in AC generator is
thinner due to step-up future.
• AC generator is cheaper than DC.
So, in this project, we learned that an AC
generator is a device that converts
mechanical energy into electrical energy
in the form of alternating EMF or
alternating current. It is based on the
principle of electromagnetic induction. In
AC generators the supply of mechanical
energy is supplied by combustion
engines, gas turbines, and steam
turbines.
The working principle of the AC generator
is based on Faraday’s Law of
electromagnetic induction. The law states
that the current will be induced in the
conductor when placed in the magnetic
field. AC generators have many uses in
your day-to-day life.

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CERTIFICATE

It is to certify that RHYTHM

MRS. ANSHU GUPTA

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