TRANSFORMER HEALTH AND ANTITHEFT MONITORING SYSTEM
PRESENTED BY
SUPERVISOR:
CO-ORDINATOR:
i
DECLARATION
This is to certify that this project report is my original work and has not been presented for a
craft certificate award in any other institution. Information from other sources has been duly
acknowledged.
Name
Sign..............................
Date..............................
This project report has been submitted for examination with my approval as the college
supervisor.
Mr.
Sign...............................
Date............................
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ACKNOWLEDGEMENT
I acknowledge the effort shown by the project supervisor _ _ _ for his tireless effort in guiding us
in this project as well as the management of the
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DEDICATION
I dedicate my gratitude to my family members and fellow class mate for encouraging me through
this course and especially the project. I also acknowledge the cooperation of my supervisor for
allocating me time for the course and especially this project.
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TABLE OF CONTENTS
DECLARATION ............................................................................................................................ ii
ACKNOWLEDGEMENT ............................................................................................................. iii
DEDICATION ............................................................................................................................... iv
LIST OF FIGURES ..................................................................................................................... viii
TABLES ......................................................................................................................................... x
LIST OF ABBREVIATIONS ........................................................................................................ xi
ABSTRACT .................................................................................................................................. xii
CHAPTER ONE ............................................................................................................................. 1
BACKGROUND INFORMATION ........................................................................................... 1
PROBLEM STATEMENT ......................................................................................................... 2
MAIN OBJECTIVE.................................................................................................................... 3
SPECIFIC OBJECTIVES ........................................................................................................... 3
JUSTIFICATION OF STUDY ................................................................................................... 3
HYPOTHESIS ............................................................................................................................ 3
BLOCK DIAGRAM ................................................................................................................... 4
v
SPECIFICATIONS ..................................................................................................................... 7
CHAPTER TWO ............................................................................................................................ 8
LITERATURE REVIEW ............................................................................................................... 8
EXISTING SYSTEMS ............................................................................................................... 8
TRANSFORMER ..................................................................................................................... 12
ULTRASONIC SENSING ....................................................................................................... 13
TEMPERATURE SENSING TECHNOLOGY ....................................................................... 17
MICROCONTROLLERS ......................................................................................................... 18
gsm module ............................................................................................................................... 24
GPS MODULE ......................................................................................................................... 26
CHAPTER THREE ...................................................................................................................... 30
PROJECT DESIGN ...................................................................................................................... 30
POWER SUPPLY ..................................................................................................................... 30
PRESSURE SENSOR .............................................................................................................. 34
ULTRASONIC LEVEL SENSOR ........................................................................................... 36
TEMPERATURE SENSING CIRCUIT................................................................................... 36
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VOLTAGE DETECTOR CIRCUIT ......................................................................................... 37
CONTROL CIRCUIT ............................................................................................................... 43
GSM / GPS MODULE ............................................................................................................. 45
SWITCHING CIRCUIT ........................................................................................................... 45
Audio alarm .............................................................................................................................. 46
Display ...................................................................................................................................... 47
CIRCUIT DIAGRAM .............................................................................................................. 48
CIRCUIT OPERATION ........................................................................................................... 49
CHAPTER FOUR ......................................................................................................................... 50
SYSTEM CONSTRUCTION ................................................................................................... 50
TEST RESULTS ....................................................................................................................... 51
CONCLUSION ......................................................................................................................... 52
RECOMMENDATION ............................................................................................................ 53
COSTING ................................................................................................................................. 54
APPENDICES .............................................................................................................................. 56
REFERENCES ............................................................................................................................. 59
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LIST OF FIGURES
Figure 1 block diagram ................................................................................................................... 4
Figure 2 transformer ..................................................................................................................... 12
Figure 3 transformer construction ................................................................................................. 13
Figure 4 LM35 .............................................................................................................................. 18
Figure 5 microcontroller architecture ........................................................................................... 21
Figure 6 PIC16F73 ........................................................................................................................ 22
Figure 7 GSM module .................................................................................................................. 26
Figure 8 SIM808 ........................................................................................................................... 29
Figure 9 transformer ..................................................................................................................... 30
Figure 10 bridge rectifier .............................................................................................................. 32
Figure 11 smoothing capacitor...................................................................................................... 33
Figure 12 voltage regulator ........................................................................................................... 34
Figure 13 pressure sensor.............................................................................................................. 35
Figure 14 ultrasonic module ......................................................................................................... 36
Figure 15 temperature sensing circuit ........................................................................................... 36
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Figure 16 detector circuit .............................................................................................................. 37
Figure 17 overvoltage circuit ........................................................................................................ 39
Figure 18 under voltage circuit ..................................................................................................... 41
Figure 19 PIC18F452 .................................................................................................................... 43
Figure 20 microcontroller circuit .................................................................................................. 44
Figure 21 SIM 808 ........................................................................................................................ 45
Figure 22 audio alarm ................................................................................................................... 46
Figure 23 Buzzer ........................................................................................................................... 47
Figure 24 LCD .............................................................................................................................. 47
Figure 25 circuit diagram .............................................................................................................. 48
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TABLES
Table 1 specifications ..................................................................................................................... 7
Table 2 test results ........................................................................................................................ 51
Table 3 costing .............................................................................................................................. 55
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LIST OF ABBREVIATIONS
LCD……………. liquid crystal display
DAC……………. digital to analog converter
ADC……………. Analog to digital converter
GSM……………. Global system for mobile communication
RF……………. radio frequency
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ABSTRACT
Transformer plays a vital role of electricity distribution. Electrification has been identified as a
key factor in the country’s vision 2030. Rampant vandalism and frequent breakdowns of
transformers has however impeded the targeted rate of electrification. This has led to heavy
losses to the Kenya Power company and a lot of inconveniencies to the electricity consumers.
Many transformers are installed in places far from the company’s office making it difficult to
monitor. This project is therefore developed. This allows for the monitoring of a transformer’s
temperature, oil level, voltage and current as well as security. When overvoltage, low oil level,
high temperature or pressure indicating the transformer is being taken off its position are
detected, it sends the information in form of an SMS to the company staffs through their mobile
phones and turns on audio alarm.
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CHAPTER ONE
1.1 BACKGROUND INFORMATION
A transformer is an electrical device that transfers energy between two or more circuits through
electromagnetic induction.
Transformers range in size from RF transformers a small cm3 fraction in volume to units
interconnecting the power grid weighing hundreds of tons. A wide range of transformer designs
are used in electronic and electric power applications. Since the invention in 1885 of the first
constant potential transformer, transformers have become essential for the AC transmission,
distribution, and utilization of electrical energy.
Kenya Power Company has been losing a lot of money through transformer vandalism and
frequent breakdowns. This has led to increased operational costs of the company leading to high
electricity bills to the users. Countering these challenges is the basis of this project.
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1.2 PROBLEM STATEMENT
Transformer forms the core of electricity distribution all over the country. With the country’s
vision 2030 set, electrification of homes in the entire country is paramount. This has been the
commitment of the government to connect as many homes as possible to the national grid. This
has however been undermined by rampant vandalism and frequent breakdowns of transformers
as crocked people seeks to make money out of it.
The transformer vandalism protection and remote monitoring system allows for the monitoring
of a transformer’s critical parameters such as temperature, oil level, voltage and current as well
as security. In case the unit detects overvoltage, low oil level, high temperature or pressure
indicating the transformer is being taken off its position, it sends the information in form of an
SMS to the company staffs through their mobile phones. it also turns on audio alarm. This will
enable remote monitoring and timely response.
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1.3 MAIN OBJECTIVE

To design, construct and test transformer health and antitheft monitoring system.
1.4 SPECIFIC OBJECTIVES

To incorporate an alarm system to alert in the case of system failure.

To use ultrasonic sensing techniques to monitor the transformer oil level.

To use GSM / GPS module to facilitate remote transformer parameters and security
monitoring by the company staff from wherever he is.
1.5 JUSTIFICATION OF STUDY
The Kenya power company has incurred heavy losses due to transformer vandalism and
breakdown. The attempted methods of countering this has yielded little and in some case no
fruits at all. There is therefore need for a better approach. This study is therefore conducted to
design a local solution that will be more efficient and reliable.
1.6 HYPOTHESIS
Upon successful completion of the study:

There will be reduced power disruption instances due to increased transformer safety and
security.

The national economy will improve due to undisrupted production in industries.
3

The losses incurred by the Kenya power company will be reduced due to reduced
incidents of transformer breakdowns and vandalisms.
1.7 BLOCK DIAGRAM
Power supply
GSM module /
Pressure sensor
GPS module
Ultrasonic
LCD
level sensor
Switching
Temperature
sensing circuit
Control
circuit
circuit
Voltage
detector circuit
Figure 1 block diagram
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Alarm
POWER SUPPLY
This ensures that the system is supplied with a stable 5 volts DC from ac mains.
PRESSURE SENSOR
This generates a 5 volts signal when pressure is released off the sensor through lifting off of
transformer.
ULTRASONIC LEVEL SENSOR
This monitors the level of the transformer oil to alert when there is need for refilling or even
alerting when there is possibility of transformer oil theft.
TEMPERATURE SENSING CIRCUIT
This converts the transformer temperature to an analog voltage signal whose magnitude is
directly proportional to the actual temperature.
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VOLTAGE DETECTOR CIRCUIT
This converts the high voltage AC to a low voltage DC whose magnitude varies proportionately
with the ac utility voltage.
CONTROL CIRCUIT
This on detecting signals from the input circuits initiates the GSM unit to send a text message.
GSM / GPS MODULE
This is the link between the site and the staff. This sends a text message to the staff when the
preset conditions have been fulfilled. The SMS also incorporates the geographical position of the
transformer.
LCD
This displays the system status in alpha-numeric form.
SWITCHING CIRCUIT
This on receiving a voltage signal from the control circuit powers the alarm.
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ALARM
This when powered generates audible sound to alert the people around.
1.8 SPECIFICATIONS
Circuit operating voltage
5V DC
Input voltage
240V AC
Circuit operating current
400mA
Trigger temperature
700C
Response time
30 second
Table 1 specifications
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CHAPTER TWO
LITERATURE REVIEW
2.1 EXISTING SYSTEMS
THERMAL OVERLOAD RELAYS
Thermal overload relays prevent an electric load from drawing too much current and
overheating. Thermal overload conditions are the most likely faults to be encountered in
industrial motor applications. They result in a rise in the motor running current, which produces
an increase in the motor's thermal dissipation and temperature. Overload protection prevents an
electric motor from drawing too much current, overheating, and literally burning out.
Thermal overload relays can be bimetallic relays, eutectic alloy relays, temperature control or
probe relays, and solid-state relays. A bimetallic device is made up of two strips of different
metals. The dissimilar metals are permanently joined. Heating the bimetallic strip causes it to
bend because the dissimilar metals expand and contract at different rates. The bimetallic strip
applies tension to a spring on a contact. If heat begins to rise, the strip bends and the spring pulls
the contacts apart, breaking the circuit. A melting alloy (or eutectic) overload relay consists of a
heater coil, a eutectic alloy, and a mechanical mechanism to activate a tripping device when an
overload occurs. The relay measures the temperature of the motor by monitoring the amount of
current being drawn. This is done indirectly through a heater coil. Temperature control relays
are used to protect the motor by directly sensing the temperature of the windings using
thermistor or RTD probes. The motor must have one or more positive temperature coefficient
(PTC) thermistor probes embedded in its windings. When the nominal operating temperature of
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the probe is reached, its resistance increases rapidly. This increase is detected by a threshold
circuit, which controls a set of relay contacts. Solid-state relays have no moving or mechanical
parts. The relay calculates the average temperature within the motor by monitoring its starting
and running currents.
USE OF CCTV
Closed-circuit television (CCTV) is the use of video cameras to transmit a signal to a specific
place, on a limited set of monitors.
It differs from broadcast television in that the signal is not openly transmitted, though it may
employ point to point wireless links. CCTV is often used for surveillance in areas that may need
monitoring such as banks, casinos, airports, military installations, and convenience stores. It is
also an important tool of distance education.
OPEN DEVICE MONITORING AND TRACKING PROTOCAL
The "Open Device Monitoring and Tracking Protocol", otherwise known as OpenDMTP, is a
protocol and framework that allows bi-directional data communications between servers and
devices (clients) over the Internet and similar networks. OpenDMTP is particularly geared
towards Location-based information (LBS) such as GPS, as well as temperature and other data
collected in remote-monitoring devices. OpenDMTP is small, and is especially suited for microdevices such as PDA's, mobile phones, and custom OEM devices.
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MOTOR TEMPERATURE MONITORING UNIT SD241-B
The motor temperature monitoring unit SD241-B (Contrac) is used to ensure proper operation of
Contrac actuators in potentially explosive areas. When a motor temperature specified according
to explosion protection class is reached due to a failure in the motor, the unit interrupts the power
supply to the Contrac power electronic unit. The motor and power electronic units are
disconnected from the mains supply. The integrated brake locks the actuator in its current
position.
XT IEC Overload Relays
The XT IEC series includes non-reversing and reversing contactors and starters as well as
overload relays and accessories. Enclosed control options include metallic and non-metallic
enclosures with circuit breakers, and North American or European fuses. Save space and
engineering design time with XT IEC series overload relays. It has the following features:

Electronic coil controller allows contactors to reduce power consumption and generate
less heat, resulting in lower cooling requirements, the ability to mount more
contactors/starters per cabinet, and an extended life on pilot devices that carry control
signals.
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
AC and DC devices with the same dimensions achieved with an electronically controlled
coil system allow for space savings and reduced engineering design time.

Integrated suppressors in DC controlled contactors offers reductions in total logistics and
inventory costs by limiting the number of products ordered and stocked.

Wiring is not required, therefore increasing installation and maintenance efficiency.

Expanded range of DC coil control voltages, allows reliable operation through
fluctuations in control voltages.

Twin terminals with separate sockets in contactors up to 400A offer installation and
application flexibility when using different size wires. The improved integrity of the
connections reduces cabling faults.
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2.2 TRANSFORMER
The Voltage Transformer can be thought of as an electrical component rather than an electronic
component. A transformer basically is very simple static (or stationary) electro-magnetic passive
electrical device that works on the principle of Faraday’s law of induction by converting
electrical energy from one value to another.
Two coil windings are electrically isolated from each other but are magnetically linked through
the common core allowing electrical power to be transferred from one coil to the other. When an
electric current passed through the primary winding, a magnetic field is developed which induces
a voltage into the secondary winding as shown.
Single Phase Voltage Transformer
Figure 2 transformer
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In other words, for a transformer there is no direct electrical connection between the two coil
windings, thereby giving it the name also of an Isolation Transformer. Generally, the primary
winding of a transformer is connected to the input voltage supply and converts or transforms the
electrical power into a magnetic field. While the job of the secondary winding is to convert this
alternating magnetic field into electrical power producing the required output voltage as shown.
Transformer Construction (single-phase)
Figure 3 transformer construction
2.3 ULTRASONIC SENSING
Ultrasonic transducers are transducers that convert ultrasound waves to electrical signals or vice
versa. Those that both transmit and receive may also be called ultrasound transceivers; many
ultrasound sensors besides being sensors are indeed transceivers because they can both sense and
transmit. These devices work on a principle similar to that of transducers used in radar and sonar
systems, which evaluate attributes of a target by interpreting the echoes from radio or sound
waves, respectively. Active ultrasonic sensors generate high frequency sound waves and evaluate
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the echo which is received back by the sensor, measuring the time interval between sending the
signal and receiving the echo to determine the distance to an object. Passive ultrasonic sensors
are basically microphones that detect ultrasonic noise that is present under certain conditions,
convert it to an electrical signal, and report it to a computer.
ULTRASONIC LEVEL SENSOR
Ultrasonic level sensors one approach commonly used of the various types of measurement-level
offered in the market today. However, there is some other very common method in the
measurement of level, such as RF Capacitance, Radar, Conductance (conductivity), and
Hydrostatic Head (tank gauging). Which method you choose, you need to understand the
underlying theory and how each one works.
Level measurement using radio frequencies (RF) is a set of different configurations of the
electrical characteristics of a capacitor. All types of this type use the frequency range from 30
KHz to 1MHz. An ultrasonic sensor consists of a transmitter and receiver, which operate using
sound waves to determine the fluid level. As for the type of ultrasonic sensor (transmitter /
receiver) using a range of 20-200 KHz, and the sonic type is a frequency of 10 KHz.
The working principle of an ultrasonic level sensors to transmit sound waves from an ultrasonic
transmitter to the surface of the liquid level to be measured. A piezoelectric crystal inside the
transducer converts electrical pulses into sound energy moves in waves at a frequency that was
14
established and at a constant speed in a particular medium. Echoes that reach the liquid surface
will be reflected and returned and received by the transducer of an ultrasonic receiver.
The time taken by sound waves to return is directly proportional to the distance between the
sensor and the piezoelectric material in the tank. Based on the measured time by the sensor is
then used as the information to calculate the level of liquid in the tank.
Velocity of sound waves can sometimes be affected due to the proper temperature variation
compensation should be provided in the sensor design. In general, the media on the surface of the
fluid is air. However, one can use a blanket of nitrogen or steam as well.
Ultrasonic Level Sensor Installation
In the non-contact design, theultrasonic level sensoris located above the tank in such a way that
sends sound waves in the form of bursts in the direction of the liquid in the tank down to below
the measurement level. Immediately, after the sound wave hits the surface of the liquid is
directed, the echo will be reflected and returned to the sensor.
UCL-510 ULTRASONIC WATER LEVEL SENSOR
The UCL-510 offers an innovative, non-contact ultrasonic level sensor with no moving parts
built for challenging fluid measurement. This accurate and reliable sensor is built for general
15
purpose, small tank applications 49.2" (1250 mm) or less and offers switch, controller and
transmitter capabilities in one multi-function transmitter. The UCL-510 is suited for corrosive
and dirty applications and is virtually maintenance free and reduces tank system hardware. The
UCL-510 combines 4 relays, 4-20mA output and pump/valve control in one small sensor. The
UCL-510 offers a total solution for fluid handling and automation.
Applications:

Water and Waste Water

Control Automation

Chemical Feed

Food and Beverage

Acids, Inks, Paints

Slurries
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2.4 TEMPERATURE SENSING TECHNOLOGY
LM 35
The LM35 is an integrated circuit sensor that can be used to measure temperature with an
electrical output proportional to the temperature (in oC).
The LM35 generates a higher output voltage than thermocouples and may not require that the
output voltage be amplified.
It has an output voltage that is proportional to the Celsius temperature.
The scale factor is 0.01V/oC.
Another important characteristic of the LM35 is that it draws only 60 micro amps from its supply
and possesses a low self-heating capability. The sensor self-heating causes less than 0.1 oC
temperature rise in still air.
The LM35 comes in many different packages, including the following.

TO-92 plastic transistor-like package,

T0-46 metal can transistor-like package

8-lead surface mount SO-8 small outline package

TO-202 package. (Shown in the picture above)
17
Figure 4 LM35
2.5 MICROCONTROLLERS
A microcontroller (μC or uC) is a solitary chip microcomputer fabricated from VLSI fabrication.
A micro controller is also known as embedded controller. Today various types of
microcontrollers are available in market with different word lengths such as 4bit, 8bit, 64bit and
128bit microcontrollers. Microcontroller is a compressed microcomputer manufactured to
control the functions of embedded systems.
Microcontroller Basics:
Any electric appliance that stores, measures, displays information or calculates comprise of a
microcontroller chip inside it. The basic structure of a microcontroller comprise of:-
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1. CPU – Microcontrollers brain is named as CPU. CPU is the device which is employed to
fetch data, decode it and at the end complete the assigned task successfully. With the help
of CPU all the components of microcontroller is connected into a single system.
Instruction fetched by the programmable memory is decoded by the CPU.
2. Memory – In a microcontroller memory chip works same as microprocessor. Memory
chip stores all programs & data. Microcontrollers are built with certain amount of ROM
or RAM (EPROM, EEPROM, etc) or flash memory for the storage of program source
codes.
3. Input/output ports – I/O ports are basically employed to interface or drive different
appliances such as- printers, LCD’s, LED’s, etc.
4. Serial Ports – These ports give serial interfaces amid microcontroller & various other
peripherals such as parallel port.
5. Timers – A microcontroller may be in-built with one or more timer or counters. The
timers & counters control all counting & timing operations within a microcontroller.
Timers are employed to count external pulses. The main operations performed by timers’
are- pulse generations, clock functions, frequency measuring, modulations, making
oscillations, etc.
6. ADC (Analog to digital converter) – ADC is employed to convert analog signals to
digital ones. The input signals need to be analog for ADC. The digital signal production
can be employed for different digital applications (such as- measurement gadgets).
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7. DAC (digital to analog converter) – this converter executes opposite functions that ADC
perform. This device is generally employed to supervise analog appliances like- DC
motors, etc.
8. Interpret Control- This controller is employed for giving delayed control for a working
program. The interpret can be internal or external.
9. Special Functioning Block – Some special microcontrollers manufactured for special
appliances like- space systems, robots, etc, comprise of this special function block. This
special block has additional ports so as to carry out some special operations.
20
Figure 5 microcontroller architecture
21
PIC Microcontroller
PIC is a peripheral interface controller, developed by general instrument’s microelectronics, in
the year of 1993. It is controlled by the software. They could be programmed to complete many
task and control a generation line and many more. PIC microcontrollers are finding their way
into new applications like smart phones, audio accessories, video gaming peripherals and
advanced medical devices.
There are many PIC controllers.
PIC 16F73 MICROCONTROLLER
Figure 6 PIC16F73
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Peripheral Features:
• Timer0: 8-bit timer/counter with 8-bit prescaler
• Timer1: 16-bit timer/counter with prescaler,
can be incremented during SLEEP via external
crystal/clock
• Timer2: 8-bit timer/counter with 8-bit period
register, prescaler and postscaler
• Two Capture, Compare, PWM modules
- Capture is 16-bit, max. resolution is 12.5 ns
- Compare is 16-bit, max. resolution is 200 ns
- PWM max. resolution is 10-bit
• 8-bit, up to 8-channel Analog-to-Digital converter
• Synchronous Serial Port (SSP) w
• Universal Synchronous Asynchronous Receiver
Transmitter (USART/SCI)
23
• Parallel Slave Port (PSP), 8-bits wide with
external RD, WR and CS controls (40/44-pin only)
• Brown-out detection circuitry for
Brown-out Reset (BOR)
2.6 GSM MODULE
A GSM modem is a specialized type of modem which accepts a SIM card, and operates over a
subscription to a mobile operator, just like a mobile phone. From the mobile operator
perspective, a GSM modem looks just like a mobile phone.
When a GSM modem is connected to a computer, this allows the computer to use the GSM
modem to communicate over the mobile network. While these GSM modems are most
frequently used to provide mobile internet connectivity, many of them can also be used for
sending and receiving SMS and MMS messages.
Huawei QuadBand, GSM/GPR Modem
Features:
• Working bands GSM/GPRS: 850 MHz/900 MHz/1800 MHz/1900 MHz
• Maximum transmission power
GSM850 Class 4 (2 W)
GSM900 Class 4 (2 W)
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GSM1800 Class 1 (1 W)
GSM1900 Class 1 (1 W)
• Receiver sensitivity < 107 dBm
• Working temperature: Normal working temperature: 20°C to +70°C
Extreme working temperatures: 30°C to 20°C and +70°C to +75°C
• Power voltage 3.3 V to 4.2 V (3.8 V is recommended.)
GSM/GPRS MODULE - SM5100B
The SM5100B is a miniature, quad-band GSM 850/EGSM 900/DCS 1800/PCS 1900 module,
which can be integrated into a great number of wireless projects. You can use this module to
accomplish almost anything a normal cell phone can - SMS text messages, GSM/GPRS, TCP/IP,
and more!
This module features two UARTS, an SPI interface, and two 10-bit ADCs. It also supports Liion battery charging, a 4x6 keypad, and an LCD interface. Inputs/outputs are available for a
speaker and microphone. An antenna does come attached to the module.
Power supplied to the module should be regulated between 3.3-4.2VDC (3.6V nominal).
25
SIM 800 MODULE
SIM800 is a complete Quad-band GSM/GPRS solution in a SMT type. SIM800 support Quadband 850/900/1800/1900MHz, it can transmit Voice, SMS and data information with low power
consumption.
Figure 7 GSM module
2.7 GPS MODULE
GPS stands for Global Positioning System by which anyone can always obtain the position
information anywhere in the world.
The GPS provides two types of services, based on the level of clearance and security of the
users:
Precise Positioning Service (PPS): This level of service is only available to the military of the
United States and its allies, certain U.S. agencies, and few selected civil users. The users must
26
have special PPS receivers with unique cryptographic algorithms and special keys. The accuracy
of the PPS service is:

Horizontal accuracy: 22 m

Vertical accuracy: 27.7 m

Time (UTC) accuracy: 200 ns
Standard Positioning Service (SPS): This level of service is designed to provide civil users
with less accurate navigation than the PPS receivers. The level of accuracy allowed for SPS is as
follows:

Horizontal accuracy: 100 m

Vertical accuracy: 156 m

Time (UTC) accuracy: 340 ns
A GPS module is a GPS navigation GPS receiver module piece of hardware that you add to other
piece of hardware (e.g. car head unit, Raspberry PI, Arduino even your computer) to give it the
possibility to receive information from GPS satellites.
SIM808 GSM/GPRS/GPS Module
SIM808 module is a GSM and GPS two-in-one function module. It is based on the latest
GSM/GPS module SIM808 from SIMCOM, supports GSM/GPRS Quad-Band network and
combines GPS technology for satellite navigation.
27
It features ultra-low power consumption in sleep mode and integrated with charging circuit for
Li-Ion batteries, that make it get a super long standby time and convenient for projects that use
rechargeable Li-Ion battery. It has high GPS receive sensitivity with 22 tracking and 66
acquisition receiver channels. Besides, it also supports A-GPS that available for indoor
localization.
The module is controlled by AT command via UART and supports 3.3V and 5V logical level.
Features

Quad-band 850/900/1800/1900MHz

GPRS multi-slot class12 connectivity: max. 85.6kbps(down-load/up-load)

GPRS mobile station class B

Controlled by AT Command (3GPP TS 27.007, 27.005 and SIMCOM enhanced AT
Commands)

Supports charging control for Li-Ion battery

Supports Real Time Clock

Supply voltage range 3.4V ~ 4.4V

Integrated GPS/CNSS and supports A-GPS

Supports 3.0V to 5.0V logic level

Low power consumption, 1mA in sleep mode

Supports GPS NMEA protocol
28

Standard SIM Card
Figure 8 SIM808
29
CHAPTER THREE
PROJECT DESIGN
3.1 POWER SUPPLY
The power supply consists of a step down transformer, rectifier circuit and smoothening
capacitors as well as voltage regulator IC.
TRANSFORMER
Figure 9 transformer
The aim of the transformer in this project is to step down voltage from 240 volts ac to 12 volts
ac. Therefore, step down laminated core transformer is the one used because it is designed to
work at a low frequency. Since the electronic circuit consumes a maximum of 500mA, the
current rating of the transformer should slightly higher than the required output in order to
increase the life of the transformer. Therefore, the transformer selected for this work is 240 volts
30
to 12 volts, 600mA laminated core transformer. To get the input current, the transformer
equation can be used.
Vp=240V
Vs= 12V
Is= 0.6 A
Therefore,
(240 / 12) = (0.6 / Ip) = 20
Ip = 0.6 / 20
Ip = 0.03A
RECTIFICATION
Full wave four diode bridge rectifier is used here. This is because it yields the best results at the
most economical level.
31
Figure 10 bridge rectifier
This is because it yields the best results at the most economical level. Since we are rectifying ac
power, rectifier diode is used here. Each diode is supposed to handle the transformer maximum
output current and voltage. Therefore, the diode current is 500mA and a peak inverse voltage of
12 volts.
The diode selected for this is therefore 1N4007. This can handle a current of 1000mA and peak
inverse voltage of 1000 volts.
32
SMOOTHING
Figure 11 smoothing capacitor
C= (5 * Io) / (Vs * f)
C = smoothing capacitance in farads (F)
Io = output current from the supply in amps (A)
Vs = supply voltage in volts (V), this is the peak value of the unsmoothed DC
f = frequency of the AC supply in hertz (Hz).
Io= 600mA= 0.6A
Vs= 12 V
F= 50
Therefore,
C = (5 * 0.6) / (12 * 50)
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C = 0.005 F
VOLTAGE REGULATOR
The 78XX positive voltage regulator IC is used. This is because our voltage is a positive one and
that it can handle up to 1 A output therefore appropriate for our load which is 500mA. Since our
required output is 5 volts, we use 7805 voltage regulator ICs.
Figure 12 voltage regulator
3.2 PRESSURE SENSOR
Push button switch are considered because of its characteristic of remaining open until pressed. It
is used in a resistor network as shown below.
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Figure 13 pressure sensor
Resistor R1 is meant to protect the reset switch from over current that would destroy it. The
switch current should not exceed 200mA. We therefore minimize the current to a lower value
than the rated which in my case is 5 milliamperes. R1 is required to reduce the current through
the switch to 5 mA. R1 can therefore be calculated as follows.
R1= 1,000 
When the switch is open, Vo is zero volts and 5 volts when the switch is.
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3.3 ULTRASONIC LEVEL SENSOR
HC-SR04 Ultrasonic Sensor is used here due to its availability. The HC-SR04 ultrasonic sensor
uses sonar to determine distance to an object. It offers excellent range accuracy and stable
readings in an easy-to-use package.
Figure 14 ultrasonic module
3.4 TEMPERATURE SENSING CIRCUIT
A negative temperature coefficient thermistor will be used. This is because of its stability over a
wide range of temperature. The thermistor is used alongside a resistor to form a potential divider
whose output voltage rises with increase in temperature. This is illustrated below.
Figure 15 temperature sensing circuit
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The thermistor needs to be protected from over current flow which can destroy it. Therefore R1
is used to protect it.
Assuming that the thermistor resistance has dropped to zero ohms when light is maximum, the
current through it is recommended not to exceed 1.2mA. Therefore,
R1=4,166  = 4.1 K
3.5 VOLTAGE DETECTOR CIRCUIT
DETECTOR CIRCUIT
There is need to step down the high voltage ac to a low peak voltage of 5 volts then feed to the
comparator.
Figure 16 detector circuit
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The diode forms a half wave rectifier. The peak voltage at the input of R1 can be calculated as
follows.
Vrms = 240 V
Vp= 339.46V
Since the comparator input impedance is very high, the current through the resistor network can
be reduced to 2mA. Therefore,
R1+R2= 339.46/ 0.002
= 169,731
R2= (5 / 339.46) * 169731
R2= 2500
R1 = 169,731- 2,500
= 167,231 
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The diode should handle a current of 2mA and a peak inverse voltage of 339.46. 1N4007 is
therefore selected because it can handle up to 1A current and a peak inverse voltage of 1,000
volts.
The ratio of input to output can be expressed as follows.
2500/ (2500+167,231) = 0.015
OVERVOLTAGE CIRCUIT
This is comprised of comparator based on the LM324 IC and reference circuit. Overvoltage
occurs at 280 volts. At this voltage, the detector output voltage can be calculated as follows.
0.015 X 280 = 4.2 volts
The reference circuit is therefore set at 4.2 volts.
Figure 17 overvoltage circuit
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The current through the divider can be reduced to 0.6mA to reduce the overall power
consumption of the circuit. To minimize the current through the divider, the total resistance of
the divider is as follows.
R3 + R4 = 5 / 0.0006
= 8,333 
The resistors can therefore be calculated as follows.
4.2= R4  5 volts
8.3
R4= 4.2  8.3
5
R4 = 7K
Therefore, R3 = 8.3K- 7K = 1.3 K
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UNDERVOLTAGE CIRCUIT
This is comprised of comparator based on the LM324 IC and reference circuit. Under voltage
occurs at 200 volts. At this voltage, the detector output voltage can be calculated as follows.
0.015 X 200 = 3 volts
The reference circuit is therefore set at 3 volts.
Figure 18 under voltage circuit
The current through the divider can be reduced to 0.6mA to reduce the overall power
consumption of the circuit. To minimize the current through the divider, the total resistance of
the divider is as follows.
R3 + R4 = 5 / 0.0006
= 8,333 
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The resistors can therefore be calculated as follows.
3= R6  5 volts
8.3
R6= 3 8.3
5
R6 = 5 K
Therefore, R2 = 8.3K- 5K = 3.3K
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3.6 CONTROL CIRCUIT
A PIC 18F452 is considered due to its availability, effectiveness and simplicity.
Figure 19 PIC18F452
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The circuit is as shown below.
Figure 20 microcontroller circuit
Resistor R is used to set pin 4 high for. Since the input impedance is very high, the current
through the resistor R can be limited to 1mA. Its value can therefore be calculated as follows.
R=V/I
R= 5 volts/0.001A
R=5KΩ
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Any crystal oscillator between 4MHz and 20MHz can be used. 16MHz crystal is selected due to
its availability locally.
3.7 GSM / GPS MODULE
SIM808 GSM-GPS module is used due to its two-in-one feature. This will reduce the bulkiness.
Figure 21 SIM 808
3.8 SWITCHING CIRCUIT
Since the buzzer is rated 12 volts, and a current of 20mA, the switching device should be rated at
least higher than 12 volts and 20mA. Therefore, BC 337 n-p-n transistor is used here. This is
rated 40 volts Vceo and a collector current of 500mA. It is described below.
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Figure 22 audio alarm
The base current of BC337 should not exceed 1.2 mA. The output of the flip flop is a maximum
of 5 volts. To offer this protection, R7 is used. Therefore,
R= 4 K
3.9 AUDIO ALARM
Self oscillating piezzo buzzer is selected since it small in size and therefore minimizes space
therefore reduce bulkiness.
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Figure 23 Buzzer
3.10 DISPLAY
A 1602 LCD is used here due to its reliability and availability.
Figure 24 LCD
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3.11 CIRCUIT DIAGRAM
Figure 25 circuit diagram
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3.12 CIRCUIT OPERATION
The upper transformer is used to step down 240V ac to 12 ac. The bridge rectifier converts the
12 V ac to 12 volts DC. The DC ripples are then filtered by the 5000 uF smoothing capacitor.
The 7805 regulator ensures a stable 5 volts supplied to the circuit.
The diode, 167K and 2.5K resistor forms the voltage detector circuit. This avails a DC voltage
proportional to the mains voltage. This is fed to the upper and lower voltage comparator IC.
When the voltage is normal, both comparator outputs are low. When the voltage is high, the
upper comparator outputs 5V to the microcontroller while when the voltage is low, the lower
comparator avails 5 volts DC to the microcontroller.
The button circuit sends 5 volts to the microcontroller when released and zero volts when
pressed.
The ultrasonic sensor monitors the transformer oil level and prompts the microcontroller to send
a text message to the staff by the use of the GSM-GPS module if the level is low. When the
current is too high, when attempt to lift the transformer is detected, or when the temperature is
too high, the microcontroller also prompts the GSM-GPS module to send a text message to the
staff to alert them. When there is an outage on the phase, the microcontroller output pin 21 goes
high and triggers the buzzer through the transistor wired as a switch. The LCD displays the status
in alpha-numeric form.
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CHAPTER FOUR
4.0 SYSTEM CONSTRUCTION
The project components were assembled on a strip board. The project was then tested. The
following considerations were made while buying the project casing:
1) The size of the circuit board
2) The height of components
3) The surface area of project peripherals
The code writing and programming was the challenge due to lack of some kits and software.
This led to sought services from external embedded systems developer.
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4.1 TEST RESULTS
TEST POINT
EXPECTED VALUE (VOLTS)
ACUAL VALUE (VOLTS)
1 (bridge output)
13V DC
14.1V DC
2 (5V regulator)
5V DC
5.2 V DC
3 (microcontroller
5V
4.5V
5V
4.8V
output)
4 (comparator)
Table 2 test results
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4.2 CONCLUSION
The project was tested. Voltage monitoring was tested by introduction of a variable resistor to
simulate mains voltage variation since it is not possible to vary utility power voltage. The project
however was considered successful.
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4.3 RECOMMENDATION
The project can be improved to incorporate GPRS monitoring which will help online monitoring
of parameters and accumulating the data over a period of time which can letter be used to assess
performance.
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4.4 COSTING
QUANTITY
PRICE PER UNIT
TOTAL PRICE
Power cable
1
100
100
Transformer
1
500
500
On/off switch
1
80
80
Capacitors
3
50
150
Diodes
4
30
120
Voltage regulator IC 1
60
60
Resistors
12
20
240
PIC 18F452
1
1800
1800
Crystal
1
200
200
IC sockets
2
100
200
LM 324
1
100
100
Relay
2
200
400
ITEM
Typing and binding
Transistor
2800
2
30
54
60
Ultrasonic module
1
600
600
LCD
1
950
950
Thermistor
1
350
350
Motion sensor
1
600
600
Strip board
1
100
100
Solder wire
5 METRES
40
200
Connector wires
4 meters
40
160
Casing
1
450
450
GSM module
1
4000
4000
TOTAL
14,200
Table 3 costing
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APPENDICES
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57
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REFERENCES
1. R. K. Rajput (201104): Electrical Technology, Paper Back.
2. Sonveer Singh. (2012). A Textbook of Control Systems Engineering. Paper back.
3. James Feher (2010). Introduction to Digital Logic with Laboratory Exercises. Global
Text Project.london.17.
4. Bimal K.Bose (2000). Power Electronics and Variable Frequency Drives - Technology
and Applications . canada.93-96.
5. Anil K. Maini (2007): Digital Electronics Principles,Devices and Applications John
Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, England.
6. Peng Zhang (2010): Advanced Industrial Control Technology.
7. L.K. MAHESWARI. (2009) Embedded Systems, Communications etc for Engineering
Students
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