MAJOR PROJECT REPORT

SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR

AWARD DEGREE OFBACHELOR OF TECHNOLOGY IN ELECTRICAL ENGINEERING

ON

THREE PHASE SELECTOR Along With

OVERVOLTAGE PROTECTION

Submitted

PREFACE

This project has been composed with the aim of covering a parts of

B.tech (------------.) syllabus as by -----------------------------------------------.

A lot of efforts have been made to make this project report interesting

for the reader. The report has been explained with the help of circuit

diagram, figures etc.

ACKNOWLEDGEMENT

The authors are highly grateful to the ----------------------, Director,

--------------------------------------------, for providing this opportunity.

 

The constant guidance and encouragement received from

----------------------------------------------------------------- has been of great help

in carrying out the project work and is acknowledged with reverential

thanks.

 

The help rendered by ----------------------- for experimentation is greatly

acknowledged.

 

The author expresses gratitude to other faculty members of Electrical

Engineering department of ------------T for their intellectual support

throughout the course of this work.

 

Finally, the authors are indebted to all whosoever have contributed in this

report work.

DECLAREATION

We hereby certify that the work, which is being presented in this project

entitled ”AUTOMATIC 3-PHASE SELECTOR ALONG WITH

OVERVOLTAGE PROTECTION” By

----------------------------------------------------------------- for partial fulfillment

of completion for engineer of Bachelor of technology in Electrical

Engineering in an authentic work done by our group.

Signature:

HOD (Electrical Engg.) External

Examiner

Table of Contents

1. Introduction.

2. Project Review

3. Need for 3phase selector

4. Project Work

Microcontroller

Block Diagram.

Component List.

Hardware.

5. Need for automation

6. Conclusion

7. Bibliography and references

INTRODUCTION

Automatic 3-phase selector and over voltage protection are two different

protection schemes used to protect the domestic power supply. These are

usually employed separately. In this project 3- phase selector provides the

automatic shifting of phases when there is any condition encountered of fault

or insufficient or excess supply which otherwise would damage the

equipment. It is only used for those appliances which work on single phase

so that if one phase fails the automatic phase selector choose the other one

available and keeps the supply continuous so we don’t need to do manual

switching or unwiring and wiring of system again which take a lot of time

and sometimes cause you a price.

The second function which is equally important is over voltage protection of

domestic power supply. When fault occurs the voltage available to

equipment goes high and can damage it so when this situation occurs the

over voltage system consisting of microcontroller tracks the sudden rise in

voltage compares it to its logic written by the programmer according to the

need of consumer and trip the circuit so the short circuit situation doesn’t

exist after .

PROJECT REVIEW

AUTOMATED 3-PHASE SELECTOR

Power instability in developing countries creates the need for automation of

phase selection or alternative sources of power to back-up the utility supply.

Most industrial and

commercial applications re dependent on power supply and if the process of

change over is manual ,not only considerable time is wasted but also the

device or machine may get damaged from human error during the change

over connections ,incurring massive losses. 

Here Automated 3 phase selector that can be installed in residential and

office premises. When any of the mains phase lines fails, it automatically

selects the available phase line (out of three phase lines or backup lines)

Auto Phase Selector (APS) system is used to ensure continuous supply to

load in case mains supply is not healthy. This unit is very useful at the sites

at which mains supply is irregular. It may be sometimes very high or

sometimes very low voltage. The frequent failures/fluctuations of power

affect life of power plant and battery. The objective of the APS is to ensure

that there is continued commercial power supplied to the site at all times so

as to ensure that the Base Transceiver Station (BTS) runs

on commercial power until all available phases are either out of electrical

tolerance or completely off.

This is a micro controller based unit and is used with three phase electrical

supply. Whenever the supply of one or two phases of a three phase electrical

line goes off, the APS system automatically distributes the electrical supply

from the active phase to the failed phases. This ensures continuous power

supply through all the three phases even if one phase is active

The basic operation and purpose is simple. Three rotary switches allow any

input phase to be routed to any output phase (or turned off). Because the

power failures are not always on all three phases, so this is a useful

capability.

If there is a failure on one phase, and one wants to use the stuff that is wired

to that phase, so we turn a different phase to power it so the original phase

comes back on.

OVERVOLTAGE PROTECTION

Overvoltage in any system is shooting voltage between one phase conductor

and earth or between phase conductors having a peak value exceeding the

corresponding peak of the highest voltage for equipment. If the voltage

exceeds more than the rated value then it can harm the connected appliances.

In this project if the voltage increases beyond the rated value the it will trip

the circuit. The logic written in the programming of microcontroller

( assembly language) does all this work of decision making and comparing

of voltage weather it is in protected range or is in over voltage stage.

With this arrangement the circuit connected and the appliances can be

protected and because it is automatic so it saves a lot of time and is very fast

and accurate.

In common applications a thyrister instead of fuse is connected in the circuit

used for protection. The thyristor will trigger in a few microseconds. This is

over 1000 times faster than an ordinary quick blow fuse. If the output

voltage exceeds the limit set by the zener, then it will conduct. The voltage

across the 4.7k resistor will rise, the thyristor switches on and the power

rails are short circuited. The duration of the short circuit will be only a few

milliseconds before the fuse blows. In these few milliseconds the voltage

will be greatly reduced. Below is a simulated transient plot, using the TINA

program. In the circuit above, and the graph the trip limit is set to 5.6 volts.

NEED FOR 3 PHASE SELECTOR WITH OVERVOLTAGE PROTECTION

Instant automatic phase change when any phase fails.

* Can get eletric supply in all the three phase lines ( Provided any one phase available)

* Need not monitor for switch back.

* Automatically changesfrom low line to proper voltage line.

* Avoids phtsical operation and suffering.

* Can slect to suit your requirement.

* Quality components are used to provide 100% efficiency

* Automatically changes the available phase lines to the non-available phase lines

* Restore to the actual lines when the failure lines are restored

* Cut off at low voltage and changes to the next lines; changes in milliseconds

* Phase changer cum changeover model with automated voltage protection

PROJECT WORKING

To do the switching we need to use SSR's, Solid State Relays, they can react

in one half of a cycle. However being jumping from phase to phase have

some phase overlap issues that would require a added half cycle delay

between shut off one phase to the connection of another phase. Plus

switching phases on the go will cause some possible spiking issues due to

the AC current cycles jumping ahead or back 120 degrees time wise.

However to get a reasonable voltage reading off each phase it would still

take a few cycles for the system to accurately detect a low voltage condition

and make the needed choice of which phase line is the best next

alternative. We sometimes have to use back to back SCR's as the switching

elements, with phase and voltage detection to decide on the switching

action.

As one phase goes low, it turns that phase off and turns the other phase on. If

done right this might work if the lines don’t go down too often in a day.

When experimenting we likely have to be phase detection to get the

switching action correct.

For the switching , perhaps a micro controller or PROM and associated

comparators to make the decisions.

If the switching SCR's don’t work because of too much phase overlaps, have

to use an alternate means such as a transistor with bridge rectifier. It is

required to analyze the effect of switching one phase to the other first

anyway though, the effect on the load. The load may have to take a brief

interruption in power. If that's not a problem, SCR's would work ok.

MICROCONTROLLERS

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small

computer on a single integrated circuit containing a processor core, memory,

and programmable input/output peripherals.

Microcontrollers are used in automatically controlled products and devices,

such as automobile engine control systems, implantable medical devices,

remote controls, office machines, appliances, power tools, toys and other

For automatic 3-phase selector

MICROCONTROLLER USED 8052

The 8052 was an enhanced version of the original 8051 that featured 256

bytes of internal RAM instead of 128 bytes, 8 KB of ROM instead of 4 KB,

and a third 16-bit timer.. The 8052 is largely considered to be obsolete

because these features and more are included in nearly all modern 8051

based microcontrollers.

The 8052 architecture provides many functions

8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-

bit microcontroller

8-bit data bus – It can access 8 bits of data in one operation

16-bit address bus – It can access 216 memory locations –

64 KB (65536 locations) each of RAM and ROM

On-chip RAM – 256 bytes (data memory)

On-chip ROM – 8 kByte (program memory)

Four byte bi-directional input/output port

UART (serial port)

Two 16-bit Counter/timers

Two-level interrupt priority

Power saving mode (on some derivatives)

The primary difference between a microprocessor and a micro controller is

that unlike the microprocessor, the micro controller can be considered to be

a true “Computer on a chip”.

In addition to the various features like the ALU, PC, SP and registers found

on a microprocessor, the micro controller also incorporates features like the

ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc.

While the microprocessor is more a general-purpose device, used for read,

write and calculations on data, the micro controller, in addition to the above

functions also controls the environment.

PIN DIAGRAM 8052.

FUNCTIONS OF PINS

ALE/PROG: Address Latch Enable output pulse for latching the low byte

of the address during accesses to external memory. ALE is emitted at a

constant rate of 1/6 of the oscillator frequency, for external timing or

clocking purposes, even when there are no accesses to external memory.

PSEN: Program Store Enable is the read strobe to external Program

Memory. When the device is executing out of external Program Memory,

PSEN is activated twice each machine cycle (except that two PSEN

activations are skipped during accesses to external Data Memory). PSEN is

not activated when the device is executing out of internal Program Memory.

EA/VPP: When EA is held high the CPU executes out of internal Program

Memory (unless the Program Counter exceeds 0FFFH in the 80C51).

Holding EA low forces the CPU to execute out of external memory

regardless of the Program Counter value. In the 80C31, EA must be

externally wired low. In the EPROM devices, this pin also receives the

programming supply voltage (VPP) during EPROM programming.

XTAL1: Input to the inverting oscillator amplifier.

XTAL2: Output from the inverting oscillator amplifier.

Port 0: Port 0 is an 8-bit open drain bidirectional port. As an open drain

output port, it can sink eight LS TTL loads. Port 0 pins that have 1s written

to them float, and in that state will function as high impedance inputs. Port 0

is also the multiplexed low-order address and data bus during accesses to

external memory

Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pullups. Port 1

pins that have 1s written to them are pulled high by the internal pullups, and

in that state can be used as inputs. As inputs, port 1 pins that are externally

being pulled low will source current because of the internal pullups.

Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pullups. Port 2

emits the high-order address byte during accesses to external memory that

use 16-bit addresses. In this application, it uses the strong internal pullups

when emitting 1s.

Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pullups. It also

serves the functions of various special features of the 80C51 Family as

follows:

Port Pin Alternate Function

P3.0 RxD (serial input port)

P3.1 TxD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

VSS : SUPPLY VOLTAGE

VCC :GROUND CICUIT POTENTIAL

8052 is applicable in various places for eg.

Finger Print based security system

High precision temperature indicator

BLOCK DIAGRAM FOR AREA APPLICATION

OTHER COMPONENTS

1. Ic base 40 pin

2. 12Mhz crystal 1nos

3. 27pf capacitor

4. 10µf,1000µf,470µf

5. In 4007diodes

6. 7805 – 1nos

7. Relays 12v 200ohm -3nos.

8. Rectifier

9. Micro switches

10.Tr 548

11.Tr 558

12.Leds or Small bubls

13.Opto-coupler pc817

14.470 ohm,400ohm Resistances

15.Display

Connecting wires, soldering iron, soldering wire etc as per requirement

COMPONENT AND HARDWARE DESCRIPTION

RESISTORS

A linear resistor is a linear, passive two-terminal electrical component that

implements electrical resistance as a circuit element. The current through a

resistor is in direct proportion to the voltage across the resistor's terminals.

Thus, the ratio of the voltage applied across a resistor's terminals to the

intensity of current through the circuit is called resistance

Resistors used here for protection purpose

CAPACITORS

A capacitor can store charge, and its capacity to store charge is called

capacitance. Capacitors consist of two conducting plates, separated by an

insulating material (known as dielectric). The two plates are joined with two

leads. The dielectric could be air, mica, paper, ceramic, polyester,

polystyrene, etc. This dielectric gives name to the capacitor. Like paper

capacitor, mica capacitor etc.

THE DIODE

Diodes are polarized, which means that they must be inserted into the PCB

the correct way round. This is because an electric current will only flow

through them in one direction (like air will only flow one way trough a tyre

valve). Diodes have two connections, an anode and a cathode. The cathode

is always identified by a dot, ring or some other mark.

OPTOCOUPLERS

Opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is

"an electronic device designed to transfer electrical signals by utilizing light

waves to provide coupling with electrical isolation between its input and

output. The main purpose of an opto-isolator is "to prevent high voltages or

rapidly changing voltages on one side of the circuit from damaging

components or distorting transmissions on the other side.

CRYSTAL

The crystal oscillator is an electronic circuit that uses the mechanical

resonance of a vibrating crystal of piezoelectrical material to create an

electrical signal with a very precise frequency. this frequency is commonly

used to keep track of time to provide a stable clock signal for digital

integrated circuit and to stabilize frequencies for radio transmitters and

receivers.the most common type of piezoelectric resonator used is a quartz

crystal, so oscillator circuit designed around them became known as ‘crystal

oscillators.’

Power Supply

For TTL circuits, the power supply pin is labeled Vcc and its nominal value.

For CMOS ICs, the power supply pin is labeled as VDD & its nominal value

range from T3 to 18V.

RECTIFIER

Rectifier is used to convert ac power into dc power and make it ripple

free and thus suitable for use in appliances

RELAYSError: Reference source not foundA relay is an electrically

operated switch. The relay contacts can be made to operate in the pre-

arranged fashion. For instance, normally open contacts close and normally

closed contacts open. In electromagnetic relays, the contacts however

complex they might be, they have only two position i.e. OPEN and

CLOSED, whereas in case of electromagnetic switches, the contacts can

have multiple positions.

STRIP

OUT N/C

OUT N/O

SPRING

MAGNET

230V P

NEED FOR THE USE OF RELAY

The reason behind using relay for switching loads is to provide complete

electrical isolation. The means that there is no electrical connection between

the driving circuits and the driven circuits. The driving circuit may be low

voltage operated low power circuits that control several kilowatts of power.

In our circuit where a high fan could be switched on or off depending upon

the output from the telephone.

Since the relay circuit operated on a low voltage, the controlling circuit is

quite safe. In an electromagnetic relay the armature is pulled by a magnetic

force only. There is no electrical connection between the coil of a relay and

the switching contacts of the relay. If there are more than one contact they

all are electrically isolated from each other by mounting them on insulating

plates and washers. Hence they can be wired to control different circuits

independently.

Some of the popular contacts forms are described below:

1. Electromagnetic relay

2. Power Relay.

3. Time Delay Relay.

4. Latching Relay.

5. Crystal Can Relay.

6. Co-axial Relay.

TYPES OF RELAYS

1. Electromagnetic relay:

An electromagnetic relay in its simplest form consists of a coil, a DC current

passing through which produces a magnetic field. This magnetic field

attracts an armature, which in turn operates the contacts. Normally open

contacts close and normally closed contacts open. Electromagnetic relays are

made in a large variety of contacts forms.

2. Power relays:

Power relays are multi-pole heavy duty lapper type relays that are capable of

switching resistive loads of upto 25amp.. These relays are widely used for a

variety of industrial application like control of fractional horse power

motors, solenoids, heating elements and so on. These relays usually have

button like silver alloy contacts and the contact welding due to heavy in rush

current is avoided by wiping action of the contacts to quench the arc during

high voltage DC switching thus avoiding the contact welding.

3. Time Delay Relay:

A time delay relay is the one in which there is a desired amount of time

delay between the application of the actuating signal and operation of the

load switching devices.

4. Latching Relay:

In a Latching Relay, the relay contacts remain in the last energized position

even after removal of signal in the relay control circuit. The contacts are

held in the last relay-energized position after removal of energization either

electrically or magnetically. The contacts can be released to the normal

position electrically or mechanically.

5. Crystal Can Relay:

They are so called, as they resemble quartz crystal in external shapes. These

are high performance hermetically sealed miniature or sub-miniature relay

widely used in aerospace and military application. These relays usually have

gold plated contacts and thus have extremely low contact resistance. Due to

low moment of inertia of the armature and also due to statically and

dynamically balanced nature of armature, these relays switch quite reliably

even under extreme condition of shock and vibration.

6. Co-axial Relay:

A Co-axial Relay has two basic parts, an actuator which is nothing but some

kind of a coil and a cavity, housing the relay contacts. The co-axial relay are

extensively used for radio frequency switching operations of equipment

THE JUNCTION TRANSISTOR

Junction transistors consists of two junctions made from N-type and P-type

semiconductor materials and are called bipolar transistors (two polarities).

They have three connections emitter, base, and collector.

Need of automation

Doing work manually costs us time and labour . Also the fault detection and

removal is not fast and this might result in damage of appliance, so to avoid

these conditions we prefer automation of system which is fast and much

more accurate than manual procedure.

1. An automated device can replace good amount of human working force,

moreover humans are more prone to errors and in intensive conditions the

probability of error increases. Whereas an automated device can work with

diligence, versatility and with almost zero error.

2. This is why this project looks into construction and implementation of a

system involving hardware to control a variety of electrical and electronics

instruments.

What is home/office automation?

Home/office automation is the control of any or all electrical devices in our

home or office, whether we are there or away. Home/office automation is

one of the most exciting developments in technology for the home that has

come along in decades. There are hundreds of products available today that

allow us control over the devices automatically, either by remote control; or

even by voice command!

What can be automated?

Virtually anything in the home/office that is powered by electricity can be

automated and/or controlled. We can control our electrical devices with our

cordless phone from our easy chair. We can turn our porch lights on

automatically at dark or when someone approaches and can see who is at the

front door from any nearby television, and talk to them or unlock the door

from any nearby telephone. Have the security system turn off lights, close

drapes and setback the temperature when we leave and turn on the alarm

system. The possibilities are only limited by our imagination!

How is the system controlled in this project?

The program as per requirement is written and embedded onto a

microcontroller, it can be written in C language or assembly language. We

put our desired voltage limits in this program during the writing of this

program. So when this microcontroller is embedded onto the circuit with the

protection hardware system it detects the fault higherd voltage and trips the

circuit by initializing the relay and thus circuit breaker

In automated 3-phase selector the microcontroller detects the phase voltage

that weather it is appropriate for the appliance contected if yes it continues

the supply through the same phase but if the supply is fluctualting or fault

occurs in that phase it automatically shifts the phase without causing any

loss to working of appliance or without any time lapse.

So it is really helpful in protection of system and appliance uses single phase

as the shift is easy and the supply can be substituted through other phase.

POWER SUPPLY

Power supply to any component is provided as shown in the diagram below

IN 4007

1 3

+12V

A.C 2

supply 4700 uf

1000 uf

7812

CONCLUSION

Automatic 3 phase selector has a versatile application in a domestic power

supply and over voltage protection is also an important aspect of power

system. We have to deploy both the schemes separately to cope with the

problems regarding phase unbalancing and over voltage.

This project is combination of two i.e. 3 phase selector and over voltage

protection in automated way. So the need of two different circuitries is

eliminated and at the same time it can handle both types of problem.

When one phase of supply is tripped and single phase load may cut out form

supply then it gives continuous supply by using relay and phase for load is

changed after single phase tripped and load is continuous operates. It also

cuts-off low voltage line in milliseconds and changes it to the next line. It is

mainly installed at residences and small offices, where single phase

equipment is used. These are two types of models i.e. auto switch-off and

phase changer with distribution board, and it is installed according to the

requirement of consumer

So in all it can be a very useful protection scheme if further improved and

brought into the market ,will make domestic power supply more rigorous

and more reliable and less of faults.

BIBILIOGRAPHY

1. HAND BOOK OF ELECTRONICS A.K. MAINI.

2.HAND BOOK OF ELECTRICAL GUPTA & KUMAR.

3.LET US C YASHWANT KANITKAR.

4.SHYAM SERIES TATA MC GRILL.

5.DIGITAL SYSTEMS PRINCIPLES AND APPLICATION RONALD LTOCCI.

(Sixth addition)

6.ELECTRONICS FOR YOU (MARCH 1998).

7.DIGITAL DESIGN MORIS MANO.

(Second addition)

8.RELAYS AND ITS APPLICATION SHARMA, MC.

(Bpb-publishers)

10.POWER SUPPLY FOR ALL OCCASION SHARMA, MC.

(Bpb-publishers)