EVERGREEN VIDHYAASHRAM CBSE – MADURAI
(Affiliated to the Central Board of Secondary Education, New Delhi)
(Affiliation Number: 1931163)
(2024-2025)
PHYSICS PROJECT REPORT ON
AC GENERATOR
SUBMITTED BY
R.YUTHIKA SHREE
CLASS: XII
UNDER THE GUIDANCE OF
MRS VISHNUPRIYA
INDEX
TITLE PAGE.NO
Certificate 4
Acknowledgement
Introduction 6
Theory and working 7
Component of ac generator 8
Efficiency 12
Result 13
Uses 14
Losses in ac generator 15
Precautions 18
Bibliography 19
CERTIFICATE
This project entitled “AC GENERATOR” , is the investigatory project work in PHYSICS (042),
successfully completed by R.YUTHIKA SHREE class - XII, EVERGREEN
VIDHYAASHRAM CBSE SCHOOL, MADURAI with under the guidance MRS
VISHNUPRIYA (PHYSICS TEACHER) for the partial fulfillment of requirements for the
course completion in pursuance of CBSE HIGHER SECONDARY EXAM during the academic
year 2024-25.
INTERNAL EXAMINER PRINCIPAL SIGNATURE
EXTERNAL EXAMINER
ACKNOWLEDGEMENT
I would like to praise the almighty for rendering a good help and strength in successfully
completing this investigatory project.
I also wish to thank my parents for supporting me in all means for the completion of this project.
I wish to dedicate my sincere thanks to my school and my principal who has supported me with
all the facilities for the successful completion of this project.
I dedicate my heartfelt thanks and gratitude to my physics teacher for her complete guidance and
support in completing my project.
I would also like to extend my gratitude towards all teaching and non-teaching staff of
EVERGREEN VIDHYAASHRAM MADURAI and towards my friends who have supported
me a lot in the completion of this project.
INTRODUCTION
An electric generator is a device that converts mechanical energy to electrical energy. E
A generator forces electric current to flow through an external circuit. The source of
mechanical energy may be a reciprocating or turbine steam engine, water falling through
a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank,
compressed air, or any other source of mechanical energy.
Generators provide nearly all of the power for electric power grids.
THEORY AND WORKING
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 make 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.
COMPONENTS OF AN AC GENERATOR
Field
Armature
Prime mover
Rotor
Stator
Slip rings
FIELD
The field in an AC generator consists of coils of conductors within the generator that
receive a voltage from a source (called excitation) and produce a magnetic flux.
The magnetic flux in the field cuts the armature to produce a voltage. This voltage is
ultimately the output voltage of the AC generator.
ARMATURE
The armature is the part an AC generator in which voltage is produced.
This component consists of many coils of wire that are large enough.
PRIME MOVER
The prime mover is the component that is used to drive the AC generator.
The prime mover may be any type of rotating machine, such as a diesel engine, a steam
turbine, or a motor
ROTOR
The rotor of an AC generator is the rotating component of the generator, as shown in
Figure 1.
The rotor is driven by the generator's prime mover, which may be a steam turbine, gas
turbine, or diesel engine. Depending on the type of generator, this component may be the
armature or the field.
The rotor will be the armature if the voltage output is generated there; the
Rotor will be the field if the field excitation is applied there.
SLIP RINGS
Slip rings are electrical connections that are used to transfer power to and from the rotor
of an AC generator.
The slip ring consists of a circular conducting material that is connected to the rotor
windings and insulated from the shaft. Brushes ride on the slip ring as the rotor rotates.
The electrical connection to the rotor is made by connections to the brushes.
Slip rings are used in AC generators because the desired output of the generator is a sine
wave.
In a DC generator, a commutator was used to provide an outp current always flowed in
the positive direction
EFFICIENCY
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
per cent efficient.
Efficiency of an AC generator can be calculated using Equation.
Efficiency = (output/Input)X 100
OR
Efficiency = (Power Out/Power In)X 100
EFFICIENCY OF ELECTRIC GENERATOR
POWER = VOLTAGE X CURRENT
EFFICIENCY = POWER OUTPUT*100
POWER INPUT
RESULT
WHEN THE AXLE OF GENERATING MOTOR IS ROTATED, E.M.F. IS
PRODUCED BY IT.
REASON: CHANGE IN FLUX THROUGH THE WINDING OF MOTOR.
THIS E.M.F. REMAINS IN THE CIRCUIT AS LONG AS A
HENCE, FARADAY'S LAW OF ELECTROMAGNETIC INDUCTION IS VERIFIED.
AS THE SPEED OF ROTOR IS INCREASED, THE VOLTAGE AND CURRENT
PRODUCED BY GENERATOR ALSO GET INCREASED. REASON: RATE OF
CHANGE OF FLUX INCREASES.
USES
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 used to produce ac voltages for transmission via the
grid system or, locally, as portable generators. CLE
All of our household appliances run on ac current. Ex: Refrigerator, washing machines,
oven, lights, fan etc. EDGE
LOSSES IN AN AC GENERATOR
Internal Voltage Drop
The load current flows through the armature in all AC generators. The armature has some
amount of resistance and inductive reactance.
The combination of these make up what is known as the inter which causes a loss in a n
AC generator.
When the load current flows, a voltage drop is developed across the internal resistance.
This voltage drop subtracts from the output voltage and, therefore, represents generated
voltage and power that is lost and not available to the load.
Hysteresis losses
Hysteresis losses occur when iron cores in an AC generator are subjected TO effects
from the magnetic field.
The magnetic domains of the cores are held in alignment with the field in varying
numbers, dependent upon field strength.
The magnetic domains rotate, with respect to the domains not held in alignment, one
complete turn during each rotation of the rotor. This rotation of magnetic domains in the
iron causes friction and heat.
The heat produced by this friction is called magnetic hysteresis loss.
After the heat-treated silicon steel is formed to the desired shape, the laminations are
heated to a dull red and then allowed to cool.
This process, known as annealing, reduces hysteresis losses to a very low value.
To reduce hysteresis losses, most AC armatures are constructed of heat-treated silicon
steel, which has an inherently low hysteresis loss
MECHANICAL LOSSES
Rotational or mechanical losses can be caused by bearing friction, brush friction
on the commutator, and air friction (called wind age), which is caused by the air
turbuler due to armature rotation.
Careful maintenance can be instrumental in keeping bearing friction to a Clean
bearings and proper lubrication are essential to the reduction of bearing friction.
Brush friction is reduced by ensuring: proper brush seating, proper brush use, and
maintenance of proper brush tension.
A smooth and clean commutator also aids in the reduction of brush friction
PRECAUTIONS
Do all the connection carefully
•Fix all the component on cardboard with strong glue
Do not take a high voltage LED bulb (1.5V preferred)
Use only DC motor in making the model
BIBLIOGRAPHY
+ Wikipedia.com
Google search engine
Physics NCERT book
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