DAV PUBLIC SCHOOL
B.S.E.B COLONY PATNA-23
SUBJECT :- Physics(042)
Project:Transformers
(For the fullfimlment of AISSCE Practical Examinations 2024-25)
Guided by and submitted to:-
M.MADHAV SIR
(Department of Physics)
Submitted By:-
Name: SHUBHAM KUMAR CHOUDHARY
Class:XII Maths'A'
Board Roll no.:
ACKNOWLEDGEMENT
I undertook this project as part of my XII-Physics
course. I applied the best of my knowledge and
experience gained through classwork and
independent study. Developing this project was both
a complex and rewarding experience, requiring
systematic study, a clear vision, and a professional
approach throughout the design and development
stages.
I am sincerely grateful for the guidance, support, and
encouragement of those around me. I would like to
extend my heartfelt thanks to MR. M.MADHAV Sir,
my Physics teacher, for his invaluable assistance and
insightful mentorship. I am also deeply appreciative
of our principal, Shri A.C. Jha, for his support and
encouragement in allowing me the opportunity to
pursue this project.
Lastly, I want to express my gratitude to my parents
for their unwavering inspiration and for providing
the time and freedom needed to focus on this work.
Their encouragement was instrumental in bringing
this project to completion.
CERTIFICATE
This is to certify that dSHUBHAM KUMAR CHOUDHARY of class
XII 'MATHS A', Board Roll no. , of
DAV Public School,B.S.E.B Colony, Patna-23 has
successfully completed the project for the fullfilment
of AISSCE practical examination 2024-25, under the
guidance and consultation of M.MADHAV SIR
(Department of Physics).
Signature of External Signature of Internal
Examiner Examiner
INDEX
S.no. Title Page no. Remarks
Transformer and its
1 5-6
componets
Principle of a
2 7
transformer
Construction and
3 working of a 8-9
transformer
Step up and Step down
4 10-11
condition
Efficiency and energy
5 12-13
losses in a transformer
6 Uses of transformer 14
7 Conclusion 15
8 Bibliography 16
TRANSFORMER AND ITS COMPONENTS
A transformer is an electrical device that transfers electrical energy between two
or more circuits through electromagnetic induction. It is commonly used in power
distribution systems to either step up (increase) or step down (decrease) voltage
levels. Here’s a breakdown of a transformer and its main components:
Transformer Components:
1. Core:
Material: Usually made of silicon steel or ferrite, the core provides a low
reluctance path for the magnetic flux generated by the primary winding.
Shape: Common shapes include laminated sheets, which reduce eddy current
losses and improve efficiency.
2. Primary Winding:
Definition: This is the coil of wire connected to the input voltage source.
Function: When AC voltage is applied to the primary winding, it creates a
magnetic field around it, which induces a voltage in the secondary winding.
3.Secondary Winding:
Definition: This coil of wire is connected to the output load.
Function: The induced voltage in the secondary winding is either stepped up or
stepped down based on the turns ratio compared to the primary winding.
4.Insulation:
Purpose: Insulation is used between the windings and between the windings and
the core to prevent electrical shorts and provide safety.
Materials: Common insulation materials include paper, oil, or plastic.
5.Tank (for oil-filled transformers):
Definition: A metal casing that houses the transformer, providing structural support
and protection.
Function: In oil-filled transformers, the tank holds the insulating oil that cools and
insulates the windings.
6.Cooling System:
Purpose: Transformers can generate heat during operation. The cooling system
helps dissipate this heat.
Types:
• Natural Cooling: Uses air convection for cooling.
• Forced Cooling: Utilizes fans or pumps to circulate oil or air, improving
cooling efficiency.
7. Bushing:
Definition: Insulated devices that allow electrical conductors to pass safely
through the tank of the transformer.
Function: They maintain the insulation between the conductive parts and the
grounded components of the transformer.
8.Tap Changer
Function: A device used to adjust the turns ratio of the transformer, allowing for
voltage regulation under varying load conditions. It can be either on-load
(adjustable while energized) or off-load (adjustable only when de-energized).
9. Protection Devices:
Purpose: These include fuses, circuit breakers, and relays to protect the
transformer from overloads and faults.
Function: They help to disconnect the transformer from the power source in case
of a fault, ensuring safety and preventing damage.
PRINCIPLE OF A TRANSFORMER
The transformer operates on the principle of electromagnetic induction,
specifically Faraday’s Law of Electromagnetic Induction. This law states that a
changing magnetic field within a coil of wire induces an electromotive force (EMF)
or voltage in that coil. The main principles that govern the operation of a
transformer are:
1. Magnetic Induction: When an alternating current (AC) flows through the
primary winding, it creates a varying magnetic field around it. This magnetic
field can induce voltage in nearby conductive coils.
2. Turns Ratio: The voltage induced in the secondary winding is determined
by the ratio of the number of turns in the primary winding to the number of
turns in the secondary winding. This is expressed mathematically as:
CONSTRUCTION AND WORKING OF TRANSFORMER
Construction of a Transformer:
A transformer consists of a rectangular laminated iron core, made of thin iron
sheets that are insulated from each other with varnish to reduce energy losses
due to eddy currents. The primary (P₁, P₂) and secondary (S₁, S₂) windings are
wound on the same core but are well-insulated from each other and from the core
itself.
The primary coil is connected to an alternating voltage source, while the
secondary coil connects to a load resistance R via an open switch S. When the
switch is open, no current flows in the secondary winding.
For an ideal transformer:
• The resistance of both windings is negligible.
• Energy losses due to the core are minimal.
• Low-frequency operation is supported by the use of soft iron, which
increases efficiency.
Working of a Transformer:
When an alternating voltage is applied to the primary coil (P₁, P₂), an alternating
current flows through it, creating a time-varying magnetic flux in the core. This
alternating flux induces an electromotive force (EMF) in both the primary and
secondary coils due to electromagnetic induction.
For an ideal transformer, all the magnetic flux generated by the primary is linked
with the secondary, so the induced EMF per turn in the primary and secondary
windings is the same.
Key Equations
Let:
Then:
STEP UP AND STEP DOWN CONDITION
• STEP UP:
A step-up transformer increases the voltage from the primary to the secondary
winding, commonly used in power transmission to raise the voltage to high levels,
reducing current and minimizing power loss.
Construction:
• The secondary winding has more turns than the primary winding
(Ns>Np), which causes a higher voltage to be induced in the secondary.
• The iron core is laminated to reduce energy losses from eddy currents.
Working:
1. Primary Side: An alternating EMF, Ep, is applied to the primary winding (P₁,
P₂), which creates an alternating current. This produces a varying magnetic
flux in the core.
2. Magnetic Induction: This changing flux induces an EMF in both the
primary and secondary windings.
3. Voltage Transformation: Since the secondary winding has more turns, the
induced voltage Es in the secondary coil is higher than Ep in the primary
coil.
• STEP DOWN:
A step-down transformer decreases the voltage from the primary to the
secondary winding, commonly used to bring high transmission voltages down to
safer, usable levels for residential and commercial applications.
Construction:
• The primary winding has more turns than the secondary winding
(Np>Ns), resulting in a lower voltage in the secondary coil.
• The core is also laminated to reduce energy losses from eddy currents.
Working:
1. Primary Side: An AC EMF Epis applied to the primary winding, generating
an alternating current and creating a magnetic flux.
2. Magnetic Induction: This alternating flux induces EMFs in both primary
and secondary windings.
3. Voltage Transformation: Since the secondary has fewer turns, the induced
EMF Es in the secondary is lower than Ep.
EFFICIENY AND ENERGY LOSS IN A TRANSFORMER
USES OF TRANSFORMER
Conclusion
Transformers are vital components in modern electrical systems,
playing a crucial role in efficiently transmitting and distributing
electrical energy across various applications. Their ability to step
up or step down voltage levels makes them indispensable in power
transmission, industrial machinery, medical imaging, and
consumer electronics. With a wide range of transformer types such
as step-up, step-down, isolation, and current transformers they
ensure that devices and systems operate safely and effectively,
minimizing energy losses and enhancing performance.
In industries such as renewable energy, telecommunications, and
healthcare, transformers facilitate the integration of new
technologies while maintaining high efficiency and reliability. As the
demand for electricity continues to grow, and with the increasing
emphasis on renewable energy sources, the importance of
transformers will only become more pronounced.
By ensuring optimal voltage levels, improving signal integrity, and
providing essential isolation and safety features, transformers
enable the smooth functioning of diverse applications. Their
versatility and reliability make them a cornerstone of modern
electrical infrastructure, supporting a sustainable and
technologically advanced future.
BIBLIOGRAPHY
The data used in this project is taken from
these sources:
1. www.google.com
2. www.wikipedia.org
3. Class 12th Physics Ncert
