Perfect 👍 You want a **3000+ word detailed description/report** on the **Automatic 3-Phase Supply Changer** (also known as *Automatic Phase Selector*). I’ll structure it as a **complete training/project-style document**, so you can directly use it for reports, presentations, or submission. --- # **Automatic 3-Phase Supply Changer – Detailed Report** --- ## **1. Introduction** Electricity plays an essential role in modern life, powering industries, homes, and critical infrastructure. In many developing countries and even in advanced systems, power interruptions and **single-phase failures** are common due to overloading, poor distribution infrastructure, or faults in supply lines. For consumers relying on **three-phase supply**, such failures can cause serious issues like equipment malfunction, production downtime, or even complete shutdown of essential operations. An **Automatic 3-Phase Supply Changer** (also called an **Automatic Phase Selector Switch**) is a device/system designed to ensure uninterrupted power supply by automatically switching the connected load to a healthy phase when one phase fails or becomes unavailable. It is especially useful in **residential complexes, small industries, hospitals, IT setups, and commercial buildings**, where continuous power supply is crucial. This report provides a **comprehensive explanation** of the Automatic 3-Phase Supply Changer, including its **principle of operation, circuit design, components used, applications, advantages, limitations, and future scope**. --- ## **2. Objective of the Project** The main objectives of designing and implementing an automatic 3-phase supply changer are: * To ensure **uninterrupted single-phase supply** from a three-phase input. * To **detect power failure** in one phase and automatically switch the load to another available healthy phase. * To **avoid manual intervention** during power interruptions. * To **improve reliability and convenience** for critical applications like hospitals, data centers, and industries. * To provide a **low-cost and efficient solution** for phase management. --- ## **3. Basics of 3-Phase Power System** Before understanding the working of an automatic phase changer, it is important to review the basics of a 3-phase system. ### 3.1 What is a 3-Phase System? * A **3-phase power system** consists of three alternating voltages of equal magnitude but with a **phase difference of 120°** between each. * The system is widely used for **generation, transmission, and distribution** of electricity because it is more efficient than single-phase systems. ### 3.2 Need for Phase Changer In practice, one of the three phases may fail due to: * Fault in the distribution line. * Maintenance shutdown. * Overload conditions. * Loose connections or equipment failure. In such cases, if the load is connected to only that failed phase, there will be a **power cut**, even though other phases are healthy. An **automatic supply changer** solves

1. AUTOMATED THREE PHASE
CHANGER
SUBMITTED BY:
Pradeep Kumar (2207350200033)
Subham Sharma (2107350200045)
Vikas Kumar (2107350200051)
RAJKIYA ENGINEERING COLLEGE,
BIJNOR
GUIDED BY:
Mr. Parvesh Sir
Department Of Electrical Engineering

2. CONTENTS
• Introduction
• Types Of Electric Power Supply
• Block diagram
• Components Used
• Applications
• Advantages
• Future Scope
• Description Of Project
• References

3. INTRODUCTION
• Automatic feature - need of the day.
• In case of the electrical appliance control using automation
ensures more safety.
• Automation becomes necessary as the rate of power outage in
developing countries becomes predominantly high.
• If processes of change-over are manual, human error may occur;
leading to machine damage, electrocution, increased down time
consequently introducing massive losses.
• However, if the starting of the generator is automatic, switching
battery voltage to ignition coil of the generator while the main
power relay switches the load, the down time would be reduced.

4. TYPES OF ELECTRIC POWER SUPPLY
• All the possible types of electric supplies are listed below:
1. Single-phase two wire supply
2. Two-phase three wire supply
3. Three-phase four wire supply
4. Backup generator
5. Uninterruptible power source (battery flywheel backup(
6. Solar power

5. • In our project, we can connect three types of sources
simultaneously and we can also set priorities to those sources.
• If the first priority source is down then it will automatically
switch to the source which is at priority number 2 without any
delay.
• If both the sources which are at priority numbers 1 & 2 are
missing, then it will switch to third source without any delay.
In this way, we can assure an uninterrupted power supply.
• We will face black out only if all the three sources are
missing.
DESCRIPTION OF PROJECT

6. BLOCK DIAGRAM

7. COMPONENTS
These are the following components that are used
• Power Supply
• Three voltage Comparators (LM741 AH1883)
• 3-input-AND gate (4073)
• Two BC 108 transistors
• Two12V ; 30mA relays
• Biasing resistors
• 240/12V; 500mA transformer
• Bridge rectifier (1N4002)
• Two voltage regulators (LM7812 and LM7805)
• Variac
• Multimeter & some other components.

8. TRANSFORMER
• Transformer is a static electrical device that transfers by
inductive coupling between its winding circuit.
• Here in this model we are using step down transformer.

9. BRIDGE RECTIFIER
• A diode bridge is an arrangement of four diodes in a bridge
circuit configuration that provides the same polarity of output
for either polarity of input.
• When used in its most common application, for conversion of
an alternating current(ac) input into a direct current(dc)
output,it is known as bridge rectifier.

10. RELAY
• Relays are electromechanical switches.
• Relays have two circuit namely load circuit and control circuit.
• The control circuit has a small coil whereas the load circuit
has a switch.
• The coil controls the operation of switch.

11. VOLTAGE REGULATOR
• A voltage regulator is designed to automatically maintain a
constant voltage level.
• A voltage regulator may use a simple feed-forward design
or may include negative feedback. It may use an
electromechanical mechanism, or electronic components.
78 Series regulator

12. IC 7806
• It is a voltage regulator meant to give regulated 6V supply when
provided with suitable input.
• The 78xx (sometimes LM78xx) is a family of self-contained
fixed linear voltage regulator integrated circuit. The 78xx family
is commonly used in electronic circuits requiring a regulated
power supply due to their ease-of-use and low cost.
• For ICs within the family, the xx is replaced with two digits,
indicating the output voltage (for example, the 7805 has a 5 volt
output, while the 7812 produces 12 volts).

13. • A miniature snap-action switch, also trademarked and
frequently known as a micro switch.
• It is an electric switch that is actuated by very little physical
force, through the use of a tipping down mechanism, sometimes
called an "over- center" mechanism.
• Switching happens reliably at specific and repeatable positions
of the actuator, which is not necessarily true of other
mechanisms.
MICRO SWITCHES

14. Change-Over/Electrical Relay Isolation Stage
• Physical size and pin arrangement: A relay is chose based on the
existing PCB to ensure that its dimensions and pin arrangement
are suitable for the designed project.
• Coil Voltage: The relay coil voltage rating and resistance were
taken into consideration.
• Coil Resistance: The circuit must be able to supply the current
required by the relay coil. From Ohm’s law,
𝑅𝑒𝑙𝑎𝑦 𝑐𝑜𝑖𝑙 𝑐𝑢𝑟𝑟𝑒𝑛𝑡=
𝑆𝑢𝑝𝑝𝑙𝑦 𝑉𝑜𝑙𝑡𝑎𝑔𝑒
𝐶𝑜𝑖𝑙 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒

15. After the construction of the automatic voltage change-over
system, a variac was used to carry out the measurement and the
results.
CHANGEOVER SWITCH

16. APPLICATIONS
This project is very useful. It removes the need of human effort
to change the phase whenever the power supply went out of
phase.
1. Hospital
2. Multiple building.
3. Lifts
4. Domestic supply
5. School and college continuity power supply
6. Call centres
7. Hotels
8. Cinema
9. Big electric farness
10. Computer based seismography

17. ADVANTAGES
1. Continuity power supply.
2. Cost is very less.
3. Less voltage drop compare to inverter.
4. Energy efficient.
5. Low voltage protection.
6. Over load protection.
7. Less maintenance compare to inverter.
8. Less space.
9. Give good efficiency of motor
10. Give suitable load

18. FUTURE SCOPE
The project have huge future scope because every home is
facing the problem of current gone in the phase and need to
put wire from one phase to the next phase. Sometimes
electric shock also takes place because of this problem.
Everyone wants this phase changing process automatic. So
we can say that the project have huge future scope.

19. [1] Research Literature Survey : 1st
Week
[2] Circuit Design & Simulation : 2nd
Week
[3] Hardware Development & Testing : 1st
Month
[4] Integration & Final Testing : 3rd
Month
[5] Report & Documentation : 4th
Month
Total Estimated Time : 4 - 5 Month
PROJECT TIMELINE

20. THANK
YOU