DESIGN AND CONSTRUCTION OF A SMARTPHASE CHANGEOVER SIMULATOR

BY

ODEYEMI KAZEEM (H/EE/11/0608)

IBRAHIM KOLAWOLE (H/EE/11/0610)

DEPARTMENT OF ELECTRICAL ELECTRONICS ENGINEERING

SCHOOL OF ENGINEERING

THE FEDERAL POLYTECHNIC, ILARO. OGUN STATE. NIGERIA.

OCTOBER, 2013.

DESIGN AND CONSTRUCTION OF A SMARTPHASE CHANGEOVER SIMULATOR

BY

ODEYEMI KAZEEM (H/EE/11/0608)

IBRAHIM KOLAWOLE (H/EE/11/0610)

A PROJECT REPORT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF HIGHER NATIONAL DIPLOMA IN THE

DEPARTMENT OF ELECTRICAL ELECTRONICS ENGINEERING, SCHOOL OF ENGINEERING, THE FEDERAL POLYTECHNIC, ILARO.

OCTOBER, 2013.

CERTIFICATION

This is to certify that this project was carried out by ODEYEMI KAZEEM and IBRAHIM KOLAWOLE under the supervision of MR ADENIJI in the Department of Electrical Electronics Engineering.

…………………………………………Supervisor’s Signature and Date

…………………………………………Head of Department’s Signature and

Date

DEDICATION

This project is dedicated to Almighty God for granting us success in our pursuit; our loving

parents for their encouragement and financial assistance given to us in our entire endeavor.

ACKNOWLEDGEMENT

First and foremost, we give all thanks and glory to Almighty God, for sparing

our lives till this time and counting us worthy of being in this great citadel of learning.

When people think the end time of a person has come, God in his infinite mercy, shows

his mighty power and makes us exist.

We acknowledge our supervisor, MR. ADENIJI for his love, patience, moral

care and endurance toward us from the beginning to the end of this project. Our regards

goes to our families, most especially our parents and our dear brothers and sisters for

their financial support and encouragement. We acknowledge the support of other

lecturers in the department of Electrical/Electronic Engineering and our fellow course

mates in the department.

ABSTRACT

This project reviewed the methods of implementing change over system and proposed a better

and cost effective approach to realizing same. Some of the approaches which have been

employed to implement changeover system include manual change over switch box, automatic

change over system with electromechanical relays and change over system with automatic

transfer switch. Each of the methods has some drawbacks that make it undesirable. Among these

drawbacks are time wastage, possibility of fire outbreak, generation of noise, frequent failure,

product damage, high component count to mention but a few. These contribute to high

maintenance cost of these methods. The approach adopted in this project is the use of solid state

relays (SSR) which eliminate totally the noise, arching, wear and tear associated with

electromechanical relays. Digital integrated circuits and microcontroller were used to reduce

the components’ counts as well as improve the speed of the system. The system also has some

desirable features like liquid crystal display (LCD) which makes the system user friendly.

Keywords: Microcontroller (P1C16F628A), Electromechanical Relays, Solid State Relays.

TABLE OF CONTENT

CONTENT PAGE

Title Page………………………………………………………………………………… i

Certification……………………………………………………………………………… ii

Dedication………………………………………………………………………………... iii

Acknowledgement……………………………………………………………………….. iv

Abstract…………………………………………………………………………………… v

Table of contents…………………………………………………………………………. vi

List of Tables……………………………………………………………………………. vii

List of Figures…………………………………………………………………………… viii

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background

1.2 Significance of the problem

1.3 Aims and Objective of study

1.4 Scope of the study (significance of the project not included)

CHAPTER TWO

2 LITERATURE REVIEW (it is important to add other sub-headings in chapter 2 here)

CHAPTER THREE

3 METHODOLOGY

3.1 Hardware equipment

3.2 Software equipment

3.2.1 Design of the system

CHAPTER FOUR

4 RESULT AND PRESENTATION

4.1 Performance Test

4.2 Presentation of Result

4.3 Discussion of Result

CHAPTER FIVE

5.0 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

5.2 Recommendations

LIST OF FIGURES

Figure 1: Block diagram of automatic changeover system with electromechanical relay

Figure 2: Normally- closed, time open.

Figure 3: Block diagram of the system.

CHAPTER ONE

1.1 INTRODUCTION

The invention of electricity and its advancement in the field of electrical engineering has made

electrical energy so vast in its application. A modern house today cannot be said to be one if it as

no use of electricity. This is because most of the items required for making life fit and

comfortable in a home function with electricity. Electrical appliances like water heater, radio,

television, fans, water pump etc. all have absolute need of electricity.

The outline of this project is selection of supply from mains, inverter and generator automatically

by using MICROCONTROLLER concept. As it is not feasible to provide all three different,

source of supply, one source with alternative switches are provided to get the same function. In

this project we have three switches which considered as three different source of supply.

When we press any of the switches it show the absence of that particular source which is

connected to a microcontroller as input signals. Here we are using PIC16F628A family

microcontroller the output of the microcontroller is given to the ULN2003 which acts as a relay

driver. This can drive up to seven relay, the output relay which are used here are 12V relay. The

output can be observed using lamp which is getting uninterrupted power supply from other

means if main supply is cut off. The power consist of a step down transformer 230/12V, which

steps down the voltage to 12V A.C, this is converted to D.C using a bridge rectifier. The ripples

are removed using a capacitive filter and it is regulated to +5V using a voltage regulator 7805

which is required for the operation of the microcontroller and other components.

This system is to proffer solution to the coming of already existing manual change over by

performing power swap from public power, inverter and to generator automatically and vice-

versa. It has the ability to eliminate the stress of manually switching on the generator when there

is public power failure.

1.2 PROBLEM STATEMENT

A manual changeover consists of a manual changeover switch box, switch gear box and cut-out

fuse or the connector fuse as described by Pocks and Mazur (1993). This changeover switch box

separates the source between generator and public supply. When there is power supply outage

form public supply, someone has to go and change the line to generator. Thus, when power

supply is restored, someone as to put of the generator and then change the source line from

generator to public supply.

In view of the above manual changeover switch system that involves man power by using ones

energy in starting the generator and switching over form public supply to generator and vice

versa when the supply is restored. The importance attached to cases of operation in hospitals and

airport. In order to save lives from generator as fast as possible makes it important for the design

and construction of a smart phase changeover simulator that will give the ideal to solve the

problem of manpower and the danger likely to be encountered in the operation of a manual

changeover.

1.3 AIM AND OBJECTIVES OF THE PROJECT

The demand for power is raising day by day and regular electricity cut as grounds to a lot of

troubles in a range of areas such as houses, hospitals and industries. In view of this, a substitute

arrangement for electricity supply is must.

In the controller for smart phase changeover simulator project, three keys are there displace the

particular breakdown of any of the three sources. When out of the three of any keys is pushed, it

conforms with the presence of exact springs keys are linked to microcontroller as incoming

signals. PIC16 families’ microcontroller is brought into use. The productivity of microcontroller

is set to the transmit driver IC which controls suitable transmission to uphold continuous power

supply to the bad. The output has to be monitored by mean of a lamp taking electricity from

main originally. On malfunctioning of the main power supply (which is deactivated by pushing

the suitable button) the load obtains power supply from the subsequent existing source, like an

inverter usually a backup power source.

If the inverter stops working it turns over to the subsequent existing power source and so on. The

electricity status, as to which power source delivers the load is also exhibited on an LCD. As it’s

not possible to give all three different power springs of supply, one spring with swap switches

are given to obtain the similar utility. Those objectives above are to be carried out achieved as

stated above

1.4 SCOPE OF PROJECT

The main scope of this project is to consume the power supply for mains, generator and inverter

must effectively and to give an uninterrupted power supply to the load.

1.5 SIGNIFICANCE OF THE PROJECT

As the economic world is rapidly growing, factory operators have sought some means of

incoming productivity and efficiency through greater use to new technology and automation.

The new industrial revolution has gone through researches about the management of factories

both in terms of day to day operations.

Automation is system whereby a manufacturer decides to extend the capacity of machines to

perform certain operation formally done by human intervention. In order words, it is the

conversion of a work performed to one replacement in order to minimize labour with electrical

or electronic process. Also, it can be used to describe non-manufacturing system in which

programed or automatic device can operate independently or nearly independently of human

control in such device as switching equipment, automatic pilots and automated guidance and

control system.

CHAPTER TWO

LITERATURE REVIEW

The smart phase change over switch is a network system that serves a means of changing from

one power supply to another. This changing is done quickly so as to reduce the period of no

power supply. To ensure the continuity of power supply, many commercial industrial facilities

depend on both utility serve and onsite generation (generator set). And because of the growing

complexity of electrical systems it becomes imperative to give attention to power supply

reliability and stability. Over the years many approaches have been implored then in configuring

a change over system. Some of them are discussed below.

MANUAL CHANGE OVER SWITCH BOX

Manual change over switch box separates the source between a generator and a public supply

whenever there’s power failure, changeover is done manually by human and the same happens

when the public power restored and this usually accompanies with low noise and electrical

sparks.

LIMITATION OF MANUAL CHANGEOVER SWITCH BOX

Below are some of the limitations of manual switch box;

1. Time wasting whenever there’s power failure.

2. It is strenuous to operate.

3. It causes device, process and product damage.

4. It can cause fire outbreak.

5. It makes a lot of noise.

6. Maintenance is more frequent as the changeover action causes wear and tears.

AUTOMATIC CHANGEOVER SYSTEM WITH ELECTRO-MECHANICAL RELAYS

(EMRs).

A relay is an electromagnetic device as it’s activated by varying it’s input in order to get desired

output. Relay are of two types, they normally close and normally open.

Recently, electromechanical relays (EMRs) have been used with other component to implement

automatic changeover. Such component can be logic gates, transistors, opto-coupler and micro-

controller etc. Most of these components make use of 5v since they are Transistor-Transistor

Logic (TTL) based. Such control system must be properly isolated from the relay as shown in the

figure 1 to avoid the flow back of a.c signal into the control electronics.

FIG 1: Block diagram of automatic changeover system with electromechanical relay.

TIME DELAY RELAY

Relay can be modified to delay opening or delay closing as a set of contact. A very short (a

fraction of a second) delay would use a copper disk between the amateur and the moving blade

assembly. Current flowing in the disk maintains magnetic field for a short time, lengthening

release time. For a slightly longer (up to a minute) delay, a dash pot is used. A dash pot is a free

prism filled with fluid that is allowed to escape slowly. The time period can be varied by

increasing or decreasing the flow rate. For longer time period, a mechanical clock work is

installed.

Basically, we have two types of time relay delay contact.

1. NOTC: This means normally-open, time closed. It is normally when the coil is

empowered.

2. NCTO: This means normally-closed, time open. The contact is closed by the application

of the relay coil, but the only after the coil has been continuously powered for the specific

amount of time. The diagram below shows the timing if a delay relay contact operates.

CONTACT STATUS

TIME

OPEN

CLOSED

ON

OFF

5 SECS

5 SECS

NCTO

FIG 2: Normally- closed, time open.

The automatic changeover system is better than the manual changeovers witch box because it is

automatic and faster, but has their limitations which are listed below.

1. Noise associated with switching of relays.

2. Wears and tears.

3. Arching which can cause fire outbreak.

4. High component count making the system more prone to failures.

CHANGEOVER WITH AUTOMATIC TRANSFER SWITCH

This type ofchangeover system has an automatic transfer switch which monitors the alternating

current (AC) voltage coming from the utility company line for power failure conditions. Upon

detection for predetermined period of time, the standby generator is activated (started), afar

which the load is transferred from utility to the standby generator. Then, on return of the utility

field, the load is switched back afar some time and the generator is stopped. The limitation of

this approach is more or less the same thing with automatic changeover system with

electromechanical relays.

DESCRIPTION OF THE NEW SYSTEM

In the view of the limitation of the above previous works, this project proposes and implements a

changeover system that drastically reduces the short comings. The noise, wears and tears

associated with EMRs are eliminated totally by the introduction of solid state relay. Digital

components were also used to make the work more reliable unlike the previously existing ones

that make use of circuit breaker. Also a PIC16F628A microcontroller was also incorporated to

help improve the speed of automation. The system is controlled by a software program

embedded in a microcontroller. This work is handy and portable compare to the bulky works

done previously. It also has some important features like liquid crystal display (LCD). Which

make the users friendly, and alarm system for indicating generator failure, automatic phase

selector for selecting most appropriate phase, another voltage and under voltage level

monitoring? Economically this project is of high cost due to the use of ICs in place is district

components.

DESCRIPTION OF SOLID STATE RELAYS

With emergence of semi-conductors technology, the production of solid state relays were made

possible which in many application are performed their predecessors. A typically solid state

relays consist of a light emitting diode (LED) optically coupled to photovoltaic device such as a

field effect transistor (FET). Light from the LED create a voltage across the photovoltaic arrays

and activate the output FET. FET is the preferred switching element in the solid state relays

because it presents a comparatively less heat. As a result of this, FET requires small heat

dissipating fins and can reduce the overall size of the solid state relays. The internal circuitry of

the typically solid state relay is shown in figure 3 while figure 4 is a solid state relay.

ADVANTAGE OF A SOLID STATE RELAY OVER AN ELECTROMECHANICAL

RELAY

Solid state relay has the following properties which gave it an edge over the EMRs

1. It has no moving coil parts.

2. It has a long operating life.

3. Bounce free operation.

4. It has immunity to electromagnetic interference.

5. It has high switching period.

6. It can be controlled by a low signal (3V).

7. Multifunction integration.

8. No arching or sparking.

9. No acoustical noise.

10. High reliability.

11. Resistance to shock and vibration.

12. Wide input voltage range.

13. High input-output isolation.

Because of the law of signal control features, solid state relays can be drilled directly by the

microcontroller without the use of interphase drivers which can save space, time and money,

reduce components count as well as improve product life, performance and reliability.

CHAPTER THREE

DESIGN METHODOLOGY AND ANALYSIS

THE HARDWARE EQUIPMENTS

1. Power Supply Block.

2. Microcontroller (P1C16F628A)

3. Transistor BC547

4. Relay

5. LCD 16 X 2

6. Diode 1N407

7. Resistors

8. Capacitors

POWER SUPPLY BLOCK: - This supply power to the system to display all the function of the

switch and the entire system.

MICROCONTROLLER (P1C16F628A): - This does the control through the software program

embedded in it. The over voltage and under voltage was achieved using the operational amplifier

LM3914 interfaced to microcontroller.

TRANSISTOR BC547: -This server as a switch and as well as an interface coupling the relay to

the MCU.

RELAY: -Is an electromagnetic device that is activated by varying its inputs in order get the

desire output of the system.

LCD (Liquid Crystal Display): -This displays all the activities of the system, making it user

friendly.

DIODE: -This is to block the back E.M.F from the relay and it also protect the transistor as well.

RESISTOR: -They are used in stabilizing any biasing current in the system.

CAPACITOR: - They are used in removing ripples i.e. Sense of waves on the surface of a

liquid of the system.

THE SOFTWARE EQUIPMENT

1. Programming language: - Mikroc.

2. Compile: - Microc from pic programs by micro-electronica.

THE DESIGN OF THE SYSTEM

The design consist of a stepdown transformer 230/12V which stepdown the voltage to 12V AC,

thus, this is converted to DC using bridge rectifier. The ripples are removed using a capacitive

filter and it is then regulated to 5V using a voltage regulator 7805 which is required for the

operation of the microcontroller and other components. The block diagram of each stages is

shown below.

BLOCK DIAGRAM OF THE SYSTEM

LCD DISPLAY

MICRO CONTROLLER

MICRO C. PROGRAMMER

RELAY PRNER

SELECTION KEY

TRANSFORMER

RECTIFIERREGULATOR

UNINTERUPTED LOAD

MAINS SUPPLY

FIG 3: Block diagram of the system.

SIMULATION OF THE SYSTEM

The simulation of the electronic circuit of the project was done using software called MICROC.

The connection was properly made by linking the appropriate component in the first module as

well as the second and third module to produce the general circuit for the design. After the

connection, the circuit was simulated and the result displayed in an oscilloscope as well as in

form of bode plat as shown on the test results. Simulation set is shown in the circuit diagram

below.

DIAGRAM 4

Fig 8: Simulation of completed system using Proetus

CHAPTER FOUR

TESTING AND RESULT OF THE SMARTPHASE CHANGEOVER

This test is carried out to determine whether the constructed smartphase changeover is working

in accordance with the design specification provided.

THE ANALYSIS

For a standard install for a grid-tie / backup inverter: we select a critical load and connect them to

a sub-panel which is fed from the main panel via the inverter, this allow it to back feed the grid

through the mains while also being able to power those critical loads when the grids goes down.

For back-up purpose only (no grid-tie) any good off grid inverter-charger will work. The

direction is the same.

MAINS PANEL----------►INVERTER---------►CRITICAL LOAD

During normal operation, the productivity of the microcontroller is set to the transmit driver IC,

which control suitable transmit to uphold continuous power supply to the load. The output has to

be monitored by means of lamp taking electricity supply from mains originally. On

malfunctioning of the mains power supply (which is deactivated by pushing the suitable button)

the lead obtains power supply from the subsequent existing source, like an inverter which is

meant / used as backup power source.

If the inverter too stops working, it turns over to the subsequent existing power source and so on.

The electricity status, as to which power source delivers the load is exhibited on the Liquid

Crystal Display (LCD). As it is not possible to give all three different power strings of supply,

one spring with swap switches are given to obtain the similar utility.

SUMMARY OF THE OPERATION OF THE ENTIRE SYSTEM

The microcontroller monitors the mains power supply through the phase selector,

over/under voltage and mains failure units, and switches the appropriate phase to the load

through the solid state relay arrangement.

In the case of total power failure, the system sustained by backup battery, switches on a

generator, whose output is connected to the load through the solid state relay

arrangement.

The system connects the load back to utility power and automatically turns off the

generator as soon as utility power is restored.

The Liquid Crystal Display (LCD) displays all the activities of the system, making it user

friendly.

CHAPTER FIVE

DISCUSSION

From the discussion so far, it can be seen that the use of solid state relay in the implementation of

microcontroller based automatic changeover has a number of advantages over the other devices

used in the changeover system implementation. It eliminates all the noises, arching, wear and

tear associated with EMRs and manual changeover switch box. The microcontroller with its

ability to execute millions of instruction within seconds has also helped to improve the speed of

the automation besides miniaturizing the entire system.

AREA OF APPLICATION

This system can be applied in areas where continuous power supply is needed such as home,

banks, industries, hospitals and so on.

CONCLUSSION

This project has been able to show that solid state relay is a better replacement for

electromechanical relay in microcontroller based automatic changeover system. This project will

definitely be of great help to researchers and students in the matter concerning a better and

reliable switching device for automatic changeover system.

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