Over Load Protection

8/10/2019 Over Load Protection

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TRANFORMER OVERLOAD ALERT

CHAPTER 1

INTRODUCTION

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2.1 INTRODUCTION

The project report describes the design Development and Fabrication of One demo unit

of the project work TRA!FOR"#R O$#R%OAD A%#RT& b' using embedded s'stems(

ow a da') with the advancement technolog') particularl' in the field of

"icrocontrollers) all the activities in our dail' living have become a part of *nformation

technolog' and we find microcontrollers in each and ever' application( Thus) trend is directing

towards "icrocontrollers based project works( +owever) in this project work to program the

O,OFF timings different machines the microcontroller interacts with RT- *-( Then the

decisions are taken with the help of microcontroller and associated software(

The microcontroller block is pla'ing a major role in this project work( The micro

controller chip used in this project work is .*- 1/F0A and this is like heart of the project work(

The .*- 1/F0A microcontroller is a 234pin *-(

The entire project was developed in embedded s'stems( A s'stem is something that maintains

its e5istence and functions as a whole through the interaction of its parts( #(g( 6od') "ankind)

Access -ontrol) etc A s'stem is a part of the world that a person or group of persons during some

time interval and for some purpose choose to regard as a whole) consisting of interrelated

components) each component characteri7ed b' properties that are selected as being relevant to the

purpose(

#mbedded !'stem is a combination of hardware and software used to achieve a single

specific task(

#mbedded s'stems are computer s'stems that monitor) respond to) or control an e5ternal

environment(

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#nvironment connected to s'stems through sensors) actuators and other *,O interfaces(

#mbedded s'stem must meet timing 9 other constraints imposed on it b' environment(

An embedded s'stem is a microcontroller4based) software driven) reliable) real4time

control s'stem) autonomous) or human or network interactive) operating on diverse

ph'sical variables and in diverse environments and sold into a competitive and cost

conscious market(

An embedded s'stem is not a computer s'stem that is used primaril' for processing) not a

software s'stem on .- or :*;) not a traditional business or scientific application( +igh4end

embedded 9 lower end embedded s'stems( +igh4end embedded s'stem 4


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CHAPTER-3

IMPORTANT APPROACHES TO THE PROJECT

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3.1 MICROCONTROLLER

3.1.1 INTRODUCTION TO MICROCONTROLLER

A computer4on4a4chip is a variation of a microprocessor which combines the processor

core ?-.:@) some memor') and *,O ?input,output@ lines) all on one chip( The computer4on4a4chip

is called the microcomputer whose proper meaning is a computer using a ?number of@

microprocessor?s@ as its -.:s) while the concept of the microcomputer is known to be a

microcontroller( A microcontroller can be viewed as a set of digital logic circuits integrated on a

single silicon chip( This chip is used for onl' specific applications(

"ost microcontrollers do not reCuire a substantial amount of time to learn how to

efficientl' program them) although man' of them) which have Cuirks) which 'ou will have to

understand before 'ou) attempt to develop 'our first application(

Along with microcontrollers getting faster) smaller and more power efficient the' are also

getting more and more features( Often) the first version of microcontroller will just have memor'

and digital *,O) but as the device famil' matures) more and more pat numbers with var'ing

features will be available(

*n this project we used .*- 1/f0A microcontroller( For most applications) we will be

able to find a device within the famil' that meets our specifications with a minimum of e5ternal

devices) or an e5ternal but which will make attaching e5ternal devices easier) both in terms of

wiring and programming(

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For man' microcontrollers) programmers can built ver' cheapl') or even built in to the

final application circuit eliminating the need for a separate circuit( Also simplif'ing this

reCuirement is the availabilit' of micro4controllers wit !RA" and ##.RO" for control store)

which will allow program development without having to remove the micro controller for the

application circuit(

3.1.2 MICRO CONTROLLER CORE FEATURES

+igh4performance R*!- -.:(

Onl' =B single word instructions to learn(

All single c'cle instructions e5cept for program branches which are two c'cle(

Operating speed D- 4 83 "+7 clock input D- 4 833 ns instruction c'cle(

:p to 0E 5 12 words of F%A!+ .rogram "emor') :p to =/0 5 0 b'tes of Data

"emor' ?RA"@ :p to 8B/ 5 0 b'tes of ##.RO" data memor'(

.in out compatible to the .*-1/-=6,26,/,

*nterrupt capabilit' ?up to 12 sources@

#ight level deep hardware stack

Direct) indirect and relative addressing modes(

.ower4on Reset ?.OR@(

.ower4up Timer ?.>RT@ and Oscillator !tart4up Timer ?O!T@(

>atchdog Timer ?>DT@ with its own on4chip R- oscillator for reliable operation(

.rogrammable code4protection(

.ower saving !%##. mode(

!electable oscillator options(

%ow4power) high4speed -"O! F%A!+,##.RO" technolog'(


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Full' static design(

*n4-ircuit !erial .rogramming ?*-!.@ (

!ingle B$ *n4-ircuit !erial .rogramming capabilit'(

*n4-ircuit Debugging via two pins(

.rocessor read,write access to program memor'(

>ide operating voltage range 8(3$ to B(B$(

+igh !ink,!ource -urrent 8B mA(

-ommercial and *ndustrial temperature ranges(

%ow4power consumption(

*n this project we used .*- 1/f0A microcontroller( .*- means .eripheral *nterface

-ontroller( The .*- famil' having different series) the series are 184 !eries) 124 !eries) 1/4 !eries)

104 !eries) and 824 !eries( >e used 1/ !eries .*- microcontrollers(

3.1.3 ADVANTAGES OF USING A MICROCONTROLLER OVER MICROPROCESSOR

A desige! "i## $se % Mi&!'&'(!'##e! ('


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3.1., APPLICATIONS

-ell phones(

-omputers(

Robots(

*nterfacing to two pcGs(

MICROCONTROLLER

BLOCK DIAGRAM

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13

PD0-PD7PB0-PB7


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The microcontroller used here is atmega 16 which

has inbuilt adc and counter along with

microcontroller.the pin confguration and details

are given below.

The Tmega16 is a low-power !"#$ %-bitmicrocontroller based on the &' enhanced '($!architecture. B) e*ecuting power+ul instructions ina single cloc, c)cle the Tmega16 achievesthroughputs approaching 1 "(P$ per "/ allowingthe s)stem designer to optimi/e powerconsumption versus processing speed.

The &' core combines a rich instruction set

with general purpose wor,ing registers.

ll the registers are directl) connected to

the rithmetic 2ogic 3nit 4235 allowing two

independent registers to be accessed in one singleinstruction e*ecuted in one cloc, c)cle. Theresulting architecture is more code ecient whileachieving throughputs up to ten times +aster thanconventional !($! microcontrollers.

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The Tmega16 provides the +ollowing

+eatures 168 b)tes o+ (n-$)stem Programmable

9lash Program memor) with 'ead-:hile-:ritecapabilities ;1 b)tes


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D! conversions. (n $tandb) mode thecr)stal=resonator #scillator is running while the resto+ the device is sleeping.

This allows ver) +ast start-up combined with

low-power consumption. (n


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Pin Descriptions

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VCC Digital suppl) voltage.GND ?round.

Port A (PA7..PA0) Port serves as the analog

inputs to the =D !onverter.

Port also serves as an %-bit bi-directional (=# port

i+ the =D !onverter is not used. Port pins can

provide internal pull-up resistors 4selected +or eachbit5. The Port output buAers have s)mmetrical

drive characteristics with both high sin, and source

capabilit). :hen pins P0 to P7 are used as inputs

and are e*ternall) pulled low the) will source

current i+ the internal pull-up resistors are

activated. The Port pins are tri-stated when a

reset condition becomes active even i+ the cloc, isnot running.

Port B (PB7..PB0) Port B is an %-bit bi-directional

(=# port with internal pull-up resistors 4selected +or

each bit5. The Port B output buAers have

s)mmetrical drive characteristics with both high

sin, and source capabilit). s inputs Port B pins

that are e*ternall) pulled low will source current i+the pull-up resistors are activated. The Port B pins

are tri-stated when a reset

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condition becomes active even i+ the cloc, is not

running.Port B also serves the +unctions o+ various

special +eatures o+ the Tmega16 .

Port C (PC7..PC0) Port ! is an %-bit bi-directional(=# port with internal pull-up resistors 4selected +or

each bit5. The Port ! output buAers have


sin, and source capabilit). s inputs Port ! pins

that are e*ternall) pulled low will source current i+

the pull-up resistors are activated. The Port ! pins

are tri-stated when a reset

condition becomes active even i+ the cloc, is not

running. (+ the >T? inter+ace is enabled the pull-

up resistors on pins P!;4TD(5 P!4T"$5 and

P!4T!85 will be activated even i+ a reset occurs.

Port ! also serves the +unctions o+ the >T?inter+ace and other special +eatures o+ theTmega16 as listed on page 61.Port D (PD7..PD0) Port D is an %-bit bi-directional

(=# port with internal pull-up resistors 4selected +or

each bit5. The Port D output buAers have


sin, and source capabilit). s inputs Port D pinsthat are e*ternall) pulled low will source current i+

the pull-up resistors are activated. The Port D pins

are tri-stated when a reset condition becomes

active even i+ the cloc, is not running. Port D also

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serves the +unctions o+ various special +eatures o+

the Tmega16.

REET 'eset (nput. low level on this pin +or

longer than the minimum pulse length willgenerate a reset even i+ the cloc, is not running.

The minimum pulse length is 0.1 vcc. $horter

pulses are not guaranteed to generate a reset.

!TAL" (nput to the inverting #scillator amplifer

and input to the internal cloc, operating circuit.

!TAL# #utput +rom the inverting #scillatoramplifer.

AVCC &!! is the suppl) voltage pin +or Port and

the =D !onverter. (t should be e*ternall)

connected to &!! even i+ the D! is not used. (+

the D! is used it should be connected

to &!! through a low-pass flter.

ARE$ '


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E F 2$B bsolute ccurac)

E 1 - 60 Gs !onversion Time

E 3p to 1; ,$P$ at "a*imum 'esolutionE % "ultiple*ed $ingle


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FIG 3.3 POER SUPPLY UNIT

POER SUPPLY UNIT COSISTS OF FOLLOING UNITS

1@ !tep down transformer

8@ Rectifier unit

=@ *nput filter

2@ Regulator unit

v@ Output filter

3.3.1 STEP DON TRANSFORMER

The !tep down Transformer is used to step down the main suppl' voltage from 8=3$ A-

to lower value( This 8=3 A- voltage cannot be used directl') thus it is stepped down( The

Transformer consists of primar' and secondar' coils( To reduce or step down the voltage) the

transformer is designed to contain less number of turns in its secondar' core( The output from the

secondar' coil is also A- waveform( Thus the conversion from A- to D- is essential( This

conversion is achieved b' using the Rectifier -ircuit,:nit(

S(e+ d'" (!%s/'!*e!scan step down incoming voltage) which enables 'ou to have

the correct voltage input for 'our electrical needs( For e5ample) if our eCuipment has been

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specified for input voltage of 18 volts) and the main power suppl' is 8=3 volts) we will need a

step down transformer) which decreases the incoming electrical voltage to be compatible with

'our 18 volt eCuipment(

3.3.2 RECTIFIER UNIT

The Rectifier circuit is used to convert the A- voltage into its corresponding D- voltage(

There are +alf4>ave) Full4>ave and bridge Rectifiers available for this specific function( The

most important and simple device used in Rectifier circuit is the diode( The simple function of the

diode is to conduct when forward biased and not to conduct in reverse bias(

0!idge !e&(i/ie!A bridge rectifier makes use of four diodes in a bridge arrangement to achieve

full4wave rectification( This is a widel' used configuration) both with individual diodes wired as

shown and with single component bridges where the diode bridge is wired internall'(

A di'de !idge or !idge !e&(i/ie! is an arrangement of four diodes in a bridge

configuration that provides the samepolarit'of output voltagefor either polarit' of input voltage(

>hen used in its most common application) for conversion of alternating current?A-@ input into

direct current?D-@ output) it is known as a bridge rectifier( A bridge rectifier provides full4wave

rectification from a two4wire A- input) resulting in lower cost and weight as compared to a

center4tappedtransformerdesign(

83
http://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Bridge_circuithttp://en.wikipedia.org/wiki/Polarity_(physics)http://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Center_taphttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Bridge_circuithttp://en.wikipedia.org/wiki/Polarity_(physics)http://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Center_taphttp://en.wikipedia.org/wiki/Transformer


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The Forward 6ias is achieved b' connecting the diodeGs positive with positive of the

batter' and negative with batter'Gs negative( The efficient circuit used is the Full wave 6ridge

rectifier circuit( The output voltage of the rectifier is in rippled form) the ripples from the obtained

D- voltage are removed using other circuits available( The circuit used for removing the ripples

is called Filter circuit(

3.3.3 INPUT FILTER

-apacitors are used as filter( The ripples from the D- voltage are removed and pure D-

voltage is obtained( And also these capacitors are used to reduce the harmonics of the input

voltage( The primar' action performed b' capacitor is charging and discharging( *t charges in

positive half c'cle of the A- voltage and it will discharge in negative half c'cle( !o it allows onl'

A- voltage and does not allow the D- voltage( The 1333If capacitor serves as a JreservoirJ

which maintains a reasonable input voltage to the 03B throughout the entire c'cle of the ac line

voltage( The four rectifier diodes keep recharging the reservoir capacitor on alternate half4c'cles

of the line voltage) and the capacitor is Cuite capable of sustaining an' reasonable load in between

charging pulses( This filter is fi5ed before the regulator( Thus the output is free from ripples( *nput

side the low pass filter has been used(

L'" +%ss /i#(e!

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One simple electrical circuitthat will serve as a low4pass filter consists of a resistor in

series with a load) and a capacitorin parallel with the load( The capacitor e5hibits reactance) and

blocks low4freCuenc' signals) causing them to go through the load instead( At higher freCuencies

the reactance drops) and the capacitor effectivel' functions as a short circuit( The combination of

resistance and capacitance gives 'ou the time constantof the filter K LRC?represented b' the


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can be successfull' reduced here( "eanwhile it also contains current4limiting circuitr' and

thermal overload protection) so that the *- wonMt be damaged in case of e5cessive load current it

will reduce its output voltage instead( The regulators are mainl' classified for low voltage and for

high voltage( Further the' can also be classified as

1@ .ositive regulator

*nput pin


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The 018 fi5ed voltage regulator is a monolithic integrated circuit in a

TO883 t'pe package designed for use in a wide variet' of applications

including local) onboard regulation( This regulator emplo's internal current

limiting) thermal shutdown) and safe area compensation(

>ith adeCuate heat4sinking it can deliver output currents in e5cess of 1(3

ampere( Although designed primaril' as a fi5ed voltage regulator) this device

can be used with e5ternal components to obtain adjustable voltages and

currents(

3.3.5 OUTPUT FILTER

The Filter circuit is often fi5ed after the Regulator circuit( -apacitor is most often used as

filter( The principle of the capacitor is to charge and discharge( *t charges during the positive half

c'cle of the A- voltage and discharges during the negative half c'cle( The 13If and (31If

capacitors serve to help keep the power suppl' output voltage constant when load conditions

change( The electrol'tic capacitor smoothGs out an' long4term or low freCuenc' variations(

+owever) at high freCuencies this capacitor is not ver' efficient( Therefore) the (31If is included

to b'pass high4freCuenc' changes) such as digital *- switching effects) to ground(

LCD Dis+#%6

%iCuid cr'stal displa' ?%-D@ has material which combines the properties of both liCuid

and cr'stals( The' have a temperature range within which the molecules are almost as mobile as

the' would be in a liCuid) but are grouped together in an order form similar to a cr'stal(

LCD DISPLAY

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"ore microcontroller devices are using Msmart %-DM displa's to output visual information( The

following discussion covers the connection of a +itachi %-D displa' to a .*- microcontroller(

%-D displa's designed around +itachiMs %-D +D2203 module) are ine5pensive) eas' to use)

and it is even possible to produce a readout using the 0 5 03 pi5els of the displa'( +itachi %-D

displa's have a standard A!-** set of characters plus Napanese) rite ?R,>@ This line determines the direction of data between the %-D and microcontroller(

>hen it is low) data is written to the %-D( >hen it is high) data is read from the %-D(

Register select ?R!@ >ith the help of this line) the %-D interprets the t'pe of data on data lines( >hen it is

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low) an instruction is being written to the %-D( >hen it is high) a character is being

written to the %-D(

L'gi& s(%($s ' &'(!'# #ies

# 3 Access to %-D disabled

1 Access to %-D enabled

R,> 3 >riting data to %-D

1 Reading data from %-D

R! 3 *nstruction

1 -haracter

>riting data to the %-D is done in several steps

!et R,> bit to low

!et R! bit to logic 3 or 1 ?instruction or character@

!et data to data lines ?if it is writing@

!et # line to high

!et # line to low

Read data from data lines ?if it is reading@(

Reading data from the %-D is done in the same wa') but control line R,> has to be high( >hen

we send a high to the %-D) it will reset and wait for instructions( T'pical instructions sent to %-D

displa' after a reset are turning on a displa') turning on a cursor and writing characters from left

to right( >hen the %-D is initiali7ed) it is read' to continue receiving data or instructions( *f it

receives a character) it will write it on the displa' and move the cursor one space to the right( The

-ursor marks the ne5t location where a character will be written( >hen we want to write a string

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of characters) first we need to set up the starting address) and then send one character at a time(

-haracters that can be shown on the displa' are stored in data displa' ?DD@ RA"( The si7e of

DDRA" is 03 b'tes(

The %-D displa' also possesses /2 b'tes of

-haracter4e can solve this in two wa's(

One wa' is to check the 6:!P bit found on data line D( This is not the best method

because %-DMs can get stuck) and program will then sta' forever in a loop checking the 6:!P

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bit( The other wa' is to introduce a dela' in the program( The dela' has to be long enough for the

%-D to finish the operation in process( *nstructions for writing to and reading from an %-D

memor' are shown in the previous table(

At the beginning we mentioned that we needed 11 *,O lines to communicate with an %-D(

+owever) we can communicate with an %-D through a 04bit data bus( The wiring for connection

via a 04bit data bus is shown in the diagram below( *n this e5ample we use an %-D displa' with

851/ characters) labeled %"1/;818 b' Napanese maker !+AR.(

INTERFACING PIC MICROCONTROLLER TO LCD

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+

L M 7 8 0 5

1

3

2V I N

G

N

D

V O U T

3 9

2 7

1 61 5

1 31 1

8

7 8 1 2

t r a n s f o r m e r+ 5 v

3 4

1 5

1 1

87

O U T P U T

1 0 3

s t e p d o w n

2 3 0 v

2 8

9

6

4

1 N 4 0 0 7

3 0

43

1 0 k

1

1 N 4 0 0 7

3 2

2 9

2 2

1 2

3

1 N 4 0 0 7

P O T

3 6

3 1

2 4

1 2

5

3

3 5

2 6

2 3

1 0

2 5

1 3

9

2

1 9

6

52

L !1 0 0 0 u f

2 1

1

2 0

7

1

2 2 p f

1 8

1 4

2

5v

2 2 p f

3 8

3 3

1 7

1 4

4 " # $

1 N 4 0 0 7

4 0

3 7

1 0

+ 1 2 v

P%

%6f877&

o displa' Font B 5 0 dots

o 6uilt4in -ontroller+D2203 or -omp

o *nput Data2 6its or 046its *nterface

o .ower !uppl' 2$ !ingle .ower

o Dut' -'cle 1,1/ Dut'

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RELAY DRIVER

The :%8331A) :%8338A) :%833= and :%8332Aare high $oltage) high current

Darlington arra's each containing seven open collector Darlington pairs with common emitters(

#ach channel rated at B33mAand can withstand peak currents of /33mA(!uppressiondiodesare

included for inductive load driving and the inputs are pinned opposite the outputs to simplif'

board la'out(

These versatile devices are useful for driving a wide range of loads including solenoids)

rela's D- motors %#D displa's filament lamps) thermal print heads and high power buffers( The

:%8331A,8338A,833=A and 8332A are supplied in 1/pin plastic D*. packages with a copper

lead frame to reduce thermal resistance(

The' are available also in small outline package ?!O41/@ as :%8331D,8338D,833=D,8332D(

3.,.1 FEATURES OF DRIVER

!#$#DAR%*


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!*".%*FP%APO:T

3.,.2 PIN CONNECTION

FIG 3.5PIN CONNECTIONS OF A RELAY

=1


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CHAPTER-,

DESCRI0ING A0OUT PROJECT IMPLEMENTATION

=8


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,.1 0LOC7 DIAGRAME OF TRANSFORMER MONITORING AND SELF

PROTECTION SYSTEM

U ' ' ( ) T

T ' & ) * + O ' " ( ' T ( " P ( ' & T U ' (

* ( ) * O '

T ' & ) * + O ' " ( '

U ) % T

* % , ) & L

O ) ! % T % O ) % ) ,

U ) % T

P%

"%'OO)T'OLL('

L !

! % * P L & -

P O T ( ) T % & L

T ' & ) * + O ' " ( '

! ' % . ( ' U ) % T

/ % T # ' ( L & - *

0 ( - P & ! U ) % T

==


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,.2 DESCRIPTION OF THE 0LOC7 DIAGRAM

The entire project is powered with the power suppl' unit) the project it needs two

different dc power suppl' one is 18v it is maintained through %"018 positive 18v regulator

and one more dc Bv suppl' is maintained through %"03B positive Bv regulator(

.otential Transformer is designed for monitoring single4phase and three4phase power line

voltages in power metering applications( 34/v ac) B33ma(The primar' terminals can be connected

either in line4to4line or in line4to4neutral configuration( -urrent transformers provide insulation

against the high voltage of the power circuit) and also suppl' the rela's with Cuantities

proportional to those of the power circuit) but sufficientl' reduced in magnitude so that the rela's

can be made relativel' small and ine5pensive(

6ased on power transformer and current transformer the loads are working( Total four

rela' driver circuit is connected to controller( The driver is controlling four loads( #ach load is

connected to rela'( For e5ample the loads are ac load) fan) light) door motor) etc( Total four loads

are controlling b' using ke'pad(

=2


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,.3 CIRCUIT DIAGRAM

T R A N S F O R M E R

U 4

1

3

2V I N

G

N

D

V O U T

+

T R A N S F O R M E R

U 3

L M 7 8 0 5

1

3

2V I N

G

N

D

V O U T

+

R E S I S T O R

+

* T ( P ! O / )

1 ) 4 0 0 7

+ 1 2 v

+ 5 v 1 5 1 6

1 8

1 9

2 0

2

L

"

3

2

4

1 ) 4 0 0 7

) 7

+ 5 v

L " 7 8 1 2

1 21 14

1

1 ) 4 0 0 7

L O & !5

L !

1

* T ( P ! O / )

1 4

3

1 5

4

5

+ 1 2 v

O U T P U T

1 0 0 f

1 3

1 4

8

3 6

3 5

2

3

+ 1 2 .

1 0

43 2

3 1

3 8

3 7

8

9

1 0 5

10 k1 2

9

33 4

3 3

6

) O1 1

1 ) 4 0 0 7

1 05

1 ) 4 0 0 7

1 ) 4 0 0 7

2 8

2 7

7

U

L

)

2

0

0

3

1 ) 4 0 0 7

1 0 3

9 1 0

3 0

2 9

1

0

o

2m

s

1 0 0 0 f

PO T

5 61 2

81 ) 4 0 0 7

3 4

6

7

'

(

*%

*

T

O

'

1 1 1 2

2

2 4

2 3

1

2 2 p f

P

%

1

6

+

8

7

7

&

2 6

2 5

1 2

1 3

1 3

1 3 1 4

4 " # $

2 2

2 1

1 6

1 7

1 0

1 1

9

1 0 0 0 f

1 6

1 3

6

7 8

2 2 p f

4 0

3 9

1 4

1 5P# )

U ( '

+ 5 v

1 ) 4 0 0 7

1 ) 4 0 0 7

1 ) 4 0 0 7

1 ) 4 0 0 7

1 0 0 0 f

10 3

5 1 v

+ 5v+ 5 v

2 1 3

+ 5 v+ 5v

4

=B


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FIG ,.3 CIRCUIT DIAGRAM OF TRANSFORMER PROTECTION SYSTEM

,., POER SUPPLY DIAGRAM

FIG ,.3 POER SUPPLY DIAGRAM

=/


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,.5 CIRCUIT DESCRIPTION

,.5.1 POER SUPPLY

.ower suppl' unit consists of !tep down transformer) Rectifier) *nput filter)

Regulator unit) Output filter(

The !tep down Transformer is used to step down the main suppl' voltage from

8=3$ A- to lower value( This 8=3 A- voltage cannot be used directl') thus it is stepped down(

The Transformer consists of primar' and secondar' coils( To reduce or step down the voltage) the

transformer is designed to contain less number of turns in its secondar' core( The output from the

secondar' coil is also A- waveform( Thus the conversion from A- to D- is essential( This

conversion is achieved b' using the Rectifier -ircuit,:nit(

The Rectifier circuit is used to convert the A- voltage into its corresponding D-

voltage( There are +alf4>ave) Full4>ave and bridge Rectifiers available for this specific

function( The most important and simple device used in Rectifier circuit is the diode( The simple

function of the diode is to conduct when forward biased and not to conduct in reverse bias(

The Forward 6ias is achieved b' connecting the diodeGs positive with positive of the

batter' and negative with batter'Gs negative( The efficient circuit used is the Full wave 6ridge

rectifier circuit( The output voltage of the rectifier is in rippled form) the ripples from the obtained

D- voltage are removed using other circuits available( The circuit used for removing the ripples

is called Filter circuit(

-apacitors are used as filter( The ripples from the D- voltage are removed and pure

D- voltage is obtained( And also these capacitors are used to reduce the harmonics of the input

voltage( The primar' action performed b' capacitor is charging and discharging( *t charges in

=


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catiopositive half c'cle of the A- voltage and it will discharge in negative half c'cle(

+ere we used 1333IF capacitor( !o it allows onl' A- voltage and does not allow the D- voltage(

This filter is fi5ed before the regulator( Thus the output is free from ripples(

Regulator regulates the output voltage to be alwa's constant( The output voltage is

maintained irrespective of the fluctuations in the input A- voltage( As and then the A- voltage

changes) the D- voltage also changes( Thus to avoid this Regulators are used( Also when the

internal resistance of the power suppl' is greater than =3 ohms) the output gets affected( Thus this

can be successfull' reduced here( The regulators are mainl' classified for low voltage and for

high voltage( +ere we used 03B positive regulator( *t reduces the /$ dc voltage to B$ dc

$oltage(

The Filter circuit is often fi5ed after the Regulator circuit( -apacitor is most often

used as filter( The principle of the capacitor is to charge and discharge( *t charges during the

positive half c'cle of the A- voltage and discharges during the negative half c'cle( !o it allows

onl' A- voltage and does not allow the D- voltage( This filter is fi5ed after the Regulator circuit

to filter an' of the possibl' found ripples in the output received finall'( +ere we used 3(1IF

capacitor( The output at this stage is B$ and is given to the "icrocontroller

*n the power suppl' circuit two regulators are used( 03B regulator is used to

produce positive B$ dc and 018 regulator produces positive 18$ dc voltage( Rela's and :%

833= drivers operates at 18$ dc and microcontroller and sensors are operated at B$ dc voltage(

The output of the 03B regulator is connected to .*- 1/f0A microcontroller) sensors and the

output of the 018 regulator is connected to driver *-s and rela's(

,.5.2 CONTROLLER CIRCUIT

The RT- .-F0B0= is interfaced with .*-1/F0A through s'nchronous serial port

communication ?i(e() *8-4 *nter *ntegrated -ommunication@) it takes two wire for communin one

=0


39/49

is !-%4 !erial -lock and another one is !DA4 !erial Data( The RT- .-F 0B0= it connected to

B$ dc suppl' which is from 03B regulator through ==3Q resistors( "eanwhile the backup

batter' is connected to maintain the clock(

The .*- 1/f0A microcontroller is a 234pin *-( The first pin of the controller is

"-%R pin and the B$ dc suppl' is given to this pin through 13EQ resistor( This suppl' is also

given to 11thpin directl'( The 18thpin of the controller is grounded( A tank circuit consists of a 2

"+ cr'stal oscillator and two 88pf capacitors are connected to 1= thand 12thpins of the .*-(

The circuit consist one driver *- :% 833= is acts as voltage driver( *t is a 1/4 pin *-(

This is of . transistor t'pe( And this *- is a combination of transistors( At a time we can

connect seven loads to each *-( *n this project we used 8 rela's and the' connected to driver(

These rela's act as switches( The 0thpin of driver *-s is grounded and the H thpin is connected to

18$ dc voltage which is from 018 regulator(

First to two pins of driver *- are connected to R63) R61 pins of the controller

respectivel'( !imilarl' 1Bth) 1/thpins are connected to Rela's R1 and R8) respectivel'( The rela's

used in this project are of !ingle pole !ingle throw t'pe(

The Rela' Driver -ircuit is the main circuit that enables the actual control over the

applications( As per the project designed) the Rela' Driver circuit signals the appliances to be

used if the user is valid or authenticated( +ere we are using transistor as the rela' driver circuit(

Rela' is connected with the transistor) which generall' contains five pins totall'( The first two

pins are connected with the transistor and contain the magnetic coil wound between them( The

rest of the pins are common point) ormall' Open ?O@ point and ormall' -lose ?-@ point(

*nitiall' common point is in contact with ormall' -lose point( The magnetic coil also

contains an arrangement ver' similar to that of a hook( >hen suppl' is given at the suppl' point)

the magnetic coil of the rela' gets energi7ed or activated( Due to this a magnetic field is created

=H


40/49

that lifts the hook upwards( Thus the arrangement that was initiall' closed gets opened now( The

status of the rela' point gets changed ?i(e( common point gets connected with normall' open

point@(

The status of the rela' is depends upon the conduction of the transistor( The transistor

configuration used here is that of common emitter mode( The conduction of the transistor

depends on the base voltage of the transistor( The suppl' to the transistor is given from the

regulator of the power suppl' board( ormall' transistor acts as a switch( The switch then gets

activated b' the "icrocontroller(

The output of the rela' driver circuit is given to an' of the port pins( The "icrocontroller

is programmed to respond corresponding to the rela' signal obtained( Thus the transistor acts as a

switch to control the rela' and indirectl' controls the appliances( The ke's were connected in

R6) R6/) R6B) and R62 pins of the microcontroller( The %-D displa' unit it contains 1/ pins

the 1th 9 8th 4 two pins suppl' pins 1B th9 1/thpin backlight pins) = rdpin brightness adjustment

pin) 2thpin R!4reset pin) Bthpin R> pin ?read,write pin@ / thpin #4enable pin these things are

interfaced with microcontroller R-1) R-8) R-= respectivel' and thto 12thpin are connected in

.ROTD of the microcontroller(

P'(e(i%# T!%s/'!*e!

.otential Transformer is designed for monitoring single4phase and three4phase power line

voltages in power metering applications( 34/v ac) B33ma(The primar' terminals can be connected

either in line4to4line or in line4to4neutral configuration( A .otential Transformer is a special t'pe

of transformer that allows meters to take readings from electrical service connections with higher

voltage ?potential@ than the meter is normall' capable of handling without at potential transformer

C$!!e( (!%s/'!*e! =A,1A) ac@

23


41/49

-urrent transformers provide insulation against the high voltage of the power circuit) and also

suppl' the rela's with Cuantities proportional to those of the power circuit) but sufficientl'

reduced in magnitude so that the rela's can be made relativel' small and ine5pensive( The current

transformers have several reCuirements as follows mechanical construction) t'pe of insulation

?dr' or liCuid@) ratio in terms of primar' and secondar' currents or voltages) continuous thermal

rating) short4time thermal and mechanical ratings) insulation class) impulse level) service

conditions) accurac') and connections(

-urrent transformers measure power flow and provide electrical inputs to

power transformers and instruments( -urrent transformers produce either an alternating current or

alternating voltage that is proportional to the measured current( There are two basic t'pes of

current transformers wound and toroidal( >ound current transformers consist of an integral

primar' winding that is inserted in series with the conductor that carries the measured current(

Toroidal or donut4shaped current transformers do not contain a primar' winding( *nstead) the wire

that carries the current is threaded through a window in the toroidal transformer

-urrent transformer and .otential transformers are connected to bridge rectifiers( These

are used to measure the current and voltage of the load( The %-D displa's the current and voltage

of the load and the angle of the motor( And also the circuit consists of one operational amplifier

?%"=82@( One potentiometer is connected to the op4Amp( The operational amplifier is connected

to the A3 SAB pins of the .*- micro controller(

CT Pe!/'!*%&e %d Re8$i!e*e(s

%imitations when applied to rela'ing( The -T takes magneti7ing current from the primar'

circuit and since this current does not flow into the rela' branch) there is an error between the

primar' and rela' currents( This is a major source of ratio error( >inding resistance is part of the

-T burden and needs to be taken into account whean establishing the -T knee point voltage ?$k@

21


42/49

reCuirement for a particular application( This should be known The simplified -T eCuivalent

circuit given in Figure 1 is first e5amined to establish a deviceMs and the smaller it is the better(

The knee point of the -T gives an indication of the burden the -T can accommodate( Recall that

we are tr'ing to get accurate signals up to current values in e5cess of 83 times rated and this is

especiall' likel' with bus bar -TMs where fault levels are high( The knee point is the point on the

magneti7ation curve where a large increase in magneti7ing current produces a minimal increase

in the output voltage needed to drive current through the secondar' burden( This value is given

directl' in the -T specification 13%833 where the 833 figure means the -T can produce 833

volts on the output with the current being within the stated accurac'( *t must be remembered that

the ratio of a -T greatl' influences the ma5imum kneepoint that can be obtained b' a -T( The

kneepoint is basicall' the ma5imum secondar' output voltage the -T can develop( The ph'sical

si7e of the -T and how much core iron is used determines the volt per turn on the secondar'

winding( This t'picall' varies from 1(B to 8(B$ per turn) so given the number of turns which is

the -T ratio one can estimate the ma5imum obtainable kneepoint( DonMt tr' and e5pect a 233$

kneepoint out of a 233,B ratio -T

*f the -T becomes saturated because of high flu5 in the core) it will not produce an' secondar'

output current( *n fact) the secondar' will appear as load to the other parallel connected -TUs(

This is illustrated b' the short across the magneti7ing branch in Figure 8 and the load is simpl'

the -T winding resistance(

SIGNAL CONDITIONING CIRCUIT

AMPLIFIER 9LM 32,:

FEATURES

4 %ow !uppl'4-urrent Drain *ndependent of !uppl' $oltage ( ( ( 3(0 mA

4 -ommon4"ode *nput $oltage Range *ncludes


43/49

4 %ow *nput 6ias and Offset .arameters

4 *nput Offset $oltage ( ( ( = m$( ( ( 8 m$ T'p

4 *nput Offset -urrent ( ( ( 8 nA T'pe

4 *nput 6ias -urrent ( ( ( 83 nA( ( ( 1B nA T'p

4 Differential *nput $oltage Range #Cual to "a5imum4Rated !uppl' $oltage ( ( ( =8 $?8/ $ for

%"8H38@

4Open4%oop Differential $oltage Amplification ( ( ( 133 $,m$

4*nternal FreCuenc' -ompensation

These devices consist of four independent high4gain freCuenc'4compensated operational

amplifiers that are designed specificall' to operate from a single suppl' over a wide range of

voltages( Operation from split supplies also is possible if the difference between the two supplies

is = $ to =8 $) and $-- is at least1(B $ more positive than the input common4mode voltage( The

low suppl'4current drain is independent of the magnitude of the suppl' voltage(

Applications include transducer amplifiers) dc amplification blocks) and all the conventional

operational4amplifier circuits that now can be more easil' implemented in single4suppl'4voltage

s'stems(

2=


44/49

CHAPTER-5

HARDARE RE;UIREMENTS

22


45/49

5. COMPONENTS USED

1( !tep Down Transformer ? 8=3,18$@ S 1 o(

8( Diodes ?1233@ S 2 o

=( -apacitors 1333IF S 1 o) 88pF4 8 os

2( Regulators 018 S 1 o) 03B S 1 o

B( %ight #mitting Diodes %#DVs S 8os

/( Driver *-s :% 833= S 1o

( microcontroller at mega 1/

0( Rela's !ingle .ole !ingle Throw T'pe 8os

H( -r'stal Oscillator 2"+7 S 1os

13( Resistors ==3 Q S 1os)13 EQ4 B o

1 EQ S 8os

11( !ensors .otential Transformer1o)-urrent Transformer

2B


46/49

CHAPTER-

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