Faculty of Engineering




Department of Electrical and Electronic Engineering







Uninterrupted Power Supply







EE401 – Project Proposal







Student: Khaled Wehbe (20144909)




Instructor: Assist. Prof. Dr. Ali Serener













Nicosia – 2017




Electricity is one of the greatest thing that
has discovered in this world. Most of the world completely depends in their
working on computers and machines. Moreover, engineering and technical
activities are depend on electricity. Building materials and welding depend on
electricity. As we know engineering work needs electricity always. Without
electricity, many horrible scenarios will happen. After all these facts we need
for a failsafe backup plan.

This project is about an Uninterrupted
Power Supply. A very useful device that provides an alternative source in case
one of the supplies fail.


The main aim of this
project is to design a UPS with maximum efficiency used for avoiding power interruption.
The circuit automatically supplies uninterrupted power (500 VA, 230 Vac with
50Hz) to a load ex. Fan, phone charger, and Wi-Fi router through one of the
available three sources which are solar panels, mains, and battery+inverter.

According to the plan,
this system has been divided into 5 parts:

General circuit outline and analysis.

Power supply and rectification.

Control circuits for power synchronization and other
required operations.

Changeover between the sources through a relay.

Display power readings (voltage, ampere, frequency)
generated from each source.

After analyzing the plan
I will work on fourth part, which is the changing between one source and
another through a relay without power interruption.


main purpose of this project is the smart switching between the solar power,
mains, and constant d.c source regardless of the condition that who is feeding
the load. People wants to save the electricity by using solar power during
daytime but also doesn’t want in case of solar power failure person has to
switch to the constant power manually. For making this system smart, a
switching circuit should be designed to switch automatically between the

there are some characteristics that should be considered before selecting the
relay that will be used in our circuit which:

The voltage and current needed to the coil to be

The maximum output voltage that we will get.

Number of N/O and N/C needed.

Number of armature.

analyzing all these conditions and know the type and characteristic of our
relay, we need to think about our switching circuit.

If we use
an Arduino UNO along with a 4 Channel Relay Module. The Arduino will be programmed
to read a specific voltage, if the voltage that arrived to the Arduino is less than
the required it will be able to send a signal to the relay to switch to the
backup Power Source.

we can use data acquisition card that take digital input from the program
designed and give digital output to actuate the switching circuit.






















Nicosia – 2017


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