EI Class Slides 2014_Hand-Outs_Full

8/9/2019 EI Class Slides 2014_Hand-Outs_Full

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Some Application of Instrumentation Engg. /Chemical Plant

Some Application of Instrumentation Engg. /Robotics

References

1. Measurement Systems:

ErnestDoeblin &DhaneshN Manik

2. Electronic Instrumentation:

HSKalsi

3. Modern Electronic Instrumentation and Measurement techniques:

AlbertDHelfrick& William D Cooper

4. Measurement & Instrumentation Principles:

AlanSMorris

5. Transducers & Instrumentation:

D.V.SMurthy

ELECTRONIC INSTRUMENTATIONEC 010 704 (Syllabus) 3 hours lecture and 1 hour tutorialper week

References

6. Electronic Instrumentation and Measurements

DavidABell

7. InstrumentationDevices and Systems:

CSRangan,GRSarma & VSVMani,

8. Electronic Measurements and Instrumentation:

RKRajput,

9. Measurements and Instrumentation:

UABakshi,AVBakshi,

10. A Course in Electrical and Electronic Measurements and Instrumentation:

AKSawhney,

ELECTRONIC INSTRUMENTATIONEC 010 704 (Syllabus) 3 hours lecture and 1 hour tutorial per week

References


JBGupta,


Introduction toElectronicInstrumentation

Objectives ofEngineeringMeasurement

BasicMeasuringSystem

BlockDiagramandDescription

PerformanceCharacteristicsofInstruments

StaticandDynamic.

ErrorsinMeasurement

ErrorAnalysis.

Units

Dimensions

Standards.

InstrumentCalibration


Module 1(12 hrs)

References

. Measuremen st S tems:

Er en stDoeblin & Dhane Ns Manik

2. El onic tIns rumen n:

H K al si

3. Modern E ecront ic ru entation and Measurement techniqu :

Albert D Helfrick & Willa D Cooper

. Me ras emen Int strumentation Principles:

anS Morris

5. Transducers & I stru ent oti :

D.V. urthy

ELECTRONI NS MENTATIONC 010 704 yll a ) 3s hours lecture and 1 hour tutoria rp w

Referen esc

6. Ele t onic Instrumentation and Measur nem s

Davi A e

. In ust e ationDevices and Sys :

angan,G R Sarma & V V ni,

E. rect ic Measurem ntse n Instrumentation:

R K Rajput,

. Me..9 uas m ts and Instrumenta n

U A Bakshi, A V Bakshi,

10. A Course in Electrical and E t nic ments and Ins u e tion:

A aw n ,y

ELECTRONIC I U T ON 4 Syllabus) 3 ho lctur nd 1 hour tutorial per week

References

11. A Course in Electricaland Electronic Measurements and Instru entation:

J B ptu a,

ELEC ONI INS UMENT ONEC 010 704 llabu 3s) hours lecture and 1 ho torialper week

Introduction to le tr nic Instrumen t on

bjectives o Eng ne urement

Basic Mea rs ingSystem

BlockDi gramand Description

er ormance Characteristics o Instruments

LEC ONIC I STN ENT TION 704 (Syllabu 3s) hours cture and 1 hour tutorialper week

Modu 1le (12 hrs)

Slides for ECE 2014

Electronic Instrumentation (EC010 704)

(Module 0): Scope of Electronic Instrumentation of Mahatma Gandhi

Page 2 of Gathered Jaison C.S. (Asst. Prof. in ECE)

mal Jyothi College of Engineering Koovappally -


3/68

Transducers

ParametersofElectricalTransducers

Types

ActiveandPassive

AnalogueandDigital

ElectromechanicalType

Potentiometric,

Inductive,

Thermocouple,

Capacitive,

Resistive,

PiezoElectric,

StrainGauge,

IonizationGauge,

LVDT,

HallEffectSensor,

ThinFilmSensor,

ProximitySensor,

DisplacementSensor,

LoadCell,

NanoSensors

And

Ultrasonic Transducers.

Opto ElectricalTypephotoEmissive,

PhotoConductiveand

PhotoVoltaicType.

DigitalEncoders

OpticalEncoder

SelectionCriteriaforTransducers.


Module 2 (12 hrs)

Intermediate Elements

InstrumentationAmplifier,

IsolationAmplifier,

Opto Couplers.

DCandACBridges

WheatstoneBridge

GuardedWheatstoneBridge

Owen'sBridge

SheringBridge

Wein Bridge

WagnerGroundConnection.

DataTransmissionElements

BlockDiagramofTelemetrySystem

ElectricalTelemeteringSystem

Voltage,Current

and

Position

Type

RFTelemetry

PulseTelemetry

(AnalogueandDigital).

FDMTDM.


Module 3(12 hrs)

Enddevices

DigitalVoltmeterandAmmeter.

RecordingTechniques

StripChartRecorders

XTandXYRecorders.

BasicPrinciplesofDigitalRecording.

Basic

Principles

of

SignalAnalyzers

DistortionAnalyzer,

WaveAnalyzer,

SpectrumAnalyzer,

DSO.

ControlSystem

ElectronicControl

Analoguedigital

BasicPrinciplesofPLC.

BasicPrinciplesof

DataAcquisitionSystem


Module 4(12 hrs)

Basicmeasurements

Resistance,

Capacitance,

Inductance,

Voltage,

Current,

Power,

Strain,

Pressure,

Flow,

Temperature,

Force,

Torque,

mass,

conductivity,

pH.


Module 5(12 hrs)

Inductive,

Thermocouple,

Capacitive,

Resistive,

Piezo Electric,

Strain auge,

Ionization auge,

Ultrasonic Tran csd .ser

pto E ctrel ical Typephoto missive,

hoto onductive and

hotoVoltaicType.

igital ncoders

Encoder

Sele ti n r e i f r T ucers.

dedWheatstone Bridge

wen's i ge

S ering i ge

Wein Bri ge

elemetry

ulse elemetry

(Analogue and Digital).

En evic es

a o tmeteran mmeter.

c d gi T ni es

Stri Chart Re ders

nd e orders.

Basi rincip es igita Recor ing.

B sic iP nciples f g alAnalyzers

Disto t on na yz r,

Wave nal ,

SpectrumAnalyzer,

SO.

C ol ystem

e rc on c o tr

na o ue gita

a ic rin l ofPLC..

Ba ic rinciples f

ata cqu s

ELE TRO NST MENTATIONEC 010 704 a u ) ours ecture n 1 our tutoria p

Modu le 2(1 hrs)

Basi easurements

R ie stance,

a citance,

In ud anc e,c

V ge,

ent,

P er,

Str ,in

Pres er,

Flow,

Tempe ,,

Force,

Torque,

mass,

conductivity,

pH.

ECTRONIC U ONC 0 04 Syllabus) o s e an our tutoria per week

Modu 5le (12 hrs)

Slides for ECE 2014


(Module 0): Scope of Electronic Instrumentation of Mahatma Gandhi




4/68

1

References


ErnestDoeblin &DhaneshN Manik


HSKalsi




AlanSMorris


D.V.SMurthy


2

References


DavidABell


CSRangan, SGRarma & VSVMani,


RKRajput,


UABakshi,AVBakshi,


AKSawhney,


3

References


JBGupta,

ELECTRONIC INSTRUMENTATIONEC 010 704 (Syllabus) 3 hours lecture and 1 hour tutorial per week

4

Introduction toElectronicInstrumentation

ObjectivesofEngineeringMeasurement

BasicMeasuringSystem

BlockDiagramandDescription

PerformanceCharacteristicsofInstruments

StaticandDynamic.

ErrorsinMeasurement

ErrorAnalysis.

Units

Dimensions

Standards.

InstrumentCalibration


Module 1(12 hrs)

5 6

Introduction to Measurement and Instrumentation

oMeasurement

o

o result of

o quantitative comparison betw

opredeterminedstandard

o unknownmagnitude

oprocedure apparatus

ofor comparison

o mustbeprovable

o

o calibration

1

Albert D Helfrick & William D Cooper

e4. asurement & In rus mentation Principles:

Alan S Morris

. Transducers & In uts ment tion:

D.V. S Murthy

2

References

6. Electronic Inst mer nt ion a Mend asurements

Davi A Bell

7. Instrument ti n evices Sy stems:

S Rangan, SGR arma & V S ni,

8. Electronic asM mure e tsan Instrumentation:

R Rajp ,u

9. remen anst d Instrumentation:

U A sa hi,A V Ba ,i

10. A Course in Elecrict a e oc nic Measu er t a In umentation:

A K awhney,

ELECTRONI NS MENTATIONEC 010 704 Sy us) 3 hours lecture and 1 hour tutorial rp ee

3

Referen esc

11. A C r u se in Electrical and Electronic Meas er nts and In ust ment tion:

B pt ,a

ELECTRONIC I U T ON 4 Syllabus) 3 ho lctur nd 1 hour tutorial per week

4

Introduction to lectronic nstru nm tat on

Objectiveso ng neer ng easure ent

BasicMeasuring System

Block Diagramand Description

Per ormanceCharacteristics o Instruments

ELEC ONI NS RUMEN IOEC 010 704 abu 3s) hours lecture nd 1 o tutorialper week

Modu 1le (12 hrs)

In dr c o Mea rementan Instr entatio

oMeasureme

o result of

quantitaive comp isa on

o pre etermined standard

unknown agnitude

opr ure apparatus

Slides for S7 ECE 2014


(Module 1): Introduction to Electronic of Mahatma Gandhi




5/68


6/68

13

Control System

o measuring

ocontrollinginstrument

o

omeasurprovide

oimpulses

oremoteautoma tion

o

ocontrolsystem14

Modes of Measurement

oPrimary

oSecondary.

oTertiary.

15

Primary Measurement

o

ocomparing directlywith

orefstandard

oNoconversion measurand

o termsoflength

oE.g.:

o time ounting

o strokesof clock

o determining length

o with ruler16

Secondary Measurement

oIndirect

o 'onetranslation'

o

osecondarymeasurements

E.g.:

oPressure

o manometers.

oTemperature

o mercury thermometers

17

Tertiary MeasurementoIndirect

o'twoconversions

o tertiary

o

o temperature

o thermocouple

18

Generalised Measurement System andits Functional Elements

13

impulses

remote autom ton

conrol system14

ert ry.

15

Pri ary Me eu me

mpa n ectlywith

re an ar

No conve sion easurand

ter s th

E.g.:

t me unt

strokes oc

e rmining length

t rule 16

on ary Meas e nt

In i ct

one trans n

sec measurements

.E . :

P re

m eers.

Temperature

mercury the mor meer

Tert a Meas eme tIndirect

two conversions

tertiary

temperature

e r sed M sureme n Sys m andunctional Ele nm ts







7/68


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10/68

Significant Figures (cont)Example

o 1 20 300 1,2,3sig

o 123.45 5sig

o 1001 4sig

o 100.02 5sig

o 0.00001 5sig

o 1.100 2sig

o 0.00100 3sig

Types of Static Error

1) Gross human

2) Systematic

3) Random

GrossError

o humanmistakes

reading instruments

o cannoteliminate canminimize

Types of Static Error (Cont)

SystematicError

shortcomings of instrument

defective wornparts

3types

Instrumental

Environmental

Observational


Instrumentalerror

o

o mechanicalstructure

o bearingfriction irregularspringtensionstretchingofspring

o avoidedby

select suitableinstrument

particular appli

correctionfactor

calibrate instrument

Types of Static Error (Cont) Environmentalerror

o externalcondition

o inclsurroundingareacondition

osuchas temperature,humidity,

obarometerpressure

o to avoid error

airconditioner

sealing component instrument

magneticshields


Observationalerror

o by observer

omostcommon

oparallaxerror estimation error

o

. s g

0.00001 5 sig

1.100 2 sig

0.00100 3 sig

annoteliminate can minimize

Typ s ofSt Err (Cont)

Systematic ro

or gs o in t ment

fd teci worn parts

3 typ s

I u ntal

Enviro mental

Observational

ypes o c E o )

Instrumenta error

mec nca structure

bea g r ion rreguarspring tensionstre f s ing

avoide

se c u ta le nstrument

particular appli

ection actor

calibrate in trume

Types of S ti rr r (Cont Environmental rror

xternal on ition

inc surroun ing rea con ion

suc empera ure, umi i ,

es o tatic Er or ( on

Observ ionalerro

observer

st common







11/68


Randomerror

o unknowncauses

oallsystematicerror accounted

o accumulationofsmalleffect

oahigh

degree

of

accuracy

o avoidedby

o increasingnumberofreading

ostatisticalmeans

obestapproximation oftruevalue

Dynamic Characteristics

o Instr rarelyrespondinstantaneously

o changes in measuredvariables

o

omass,

o thermalcapacitance,

ofluidcapacitance

oelectricalcapacitance


o mostcommonvariations

o

oStepchange

oLinearchange

oSinusoidalchange


oStepchange

oprimaryelementsubj

o inst finite change

o measuredvariable


oLinearchange

oprimaryelementfollow

o measuredvariable

ochang linearly time


oSinusoidalchange

oprimaryelementfollow

o measuredvariable

o mag change

o accordancewith

osinusoidalfunction

o const amplitude

avoided by

increasingnum er ea i g

statistica means

best approximation true alue

d capacitance

e e trica pc citance

m cCh ct stics

st co mon variatio s

e ange

Lnear change

Si u alc an

c Char er

ep change

ary ele nt sub

i t c ange

mea variable

ynamic h act ristics

Linear change

primary elementfollo

m hara ter tic

Sinuso lchange

primar eleme ollow

measured variable







12/68

o dynamiccharacteristicsof instrument

oSpeedofresponse

o rapidity

o

instrument

respond

o changesin measuredquantity


oDynamicerror

o diff betw

otrue measuredvalue

o

no

static

error


o Lag

odelay response

o instrumentto

ochangesin measuredvariable


o Fidelity

o degreetowhich instr

o indicates change in

o measuredvariable

owithoutdynamicerror

o (faithfulreproduction).


Limiting Error

o accuracyof instr

o guaranteed within certainpercentage of

o fullscalereading

o manuf specify instr

o accurateat 2%

o withfullscaledeflection

o readinglessthanfullscale

o limitingerror

increases

Limiting Error (Cont)

Example1.6

o 600Vvoltmeter accuracy2%fullscale

o Calc limitingerrorwhen instru

ousedtomeasur 250V

o mag oflimitingerror

o 0.02x600=12V

o limitingerrorfor250V

o (12/250)x

100

=

4.8%

changes n measured qua

ag

delay response

in umentto

cha es in measure v riabl

m cCh ct stics

i e ity

degree to which instr

in icates ange in

m asure varia e

ithout dynamic error

a u repro uction .

c Char er

Li in Error

accuracy of instr

guaranteed within er inpercen ge o

full scale reading

manuf specify instr

miting rror Con

Exam .6

600 o et ter cc racy 2% ul scale

Calc imitin r r when instru

use measur 250V







13/68

Limiting Error (Cont)

o

o limitingerror voltmeterat70V 2.143%

o limitingerror ammeter 80mA 2.813%.

o Determine limitingerrorofthepower

o limitingerrorforthepower

o 2.143%+2.813%

o = 4.956%

Standard

o standard

oknownaccuratemeasure

o

o usedto

determine

o values otherphysicalquantities

o comparisonmethod

Standard

o Allstandards preserved

oBureauInternationaldesPoidsetMesures

o(BIPM)

o InternationalBureauofWeightandMeasures

o

Standard

o Fourcategoriesofstandard

o InternationalStandard

o PrimaryStandard

oSecondaryStandard

oWorkingStandard

o InternationalStd

oDefi nternationalAgreement

oRep

oclosestpossibleaccuracyattainable

ocurrentscience technology.

International Standardo PrimaryStd

oMaintained NationalStdLab

o

oFunction

o calibrationandverification

osecondarystd

oEachlab ownsecondarystd

o periodicallychecked certified

o NationalStdLab

Primary Standard

imiting rror forthe power

2. 4 + 2.

= 4.956%

val es other physical quantities

co paris method

n rd

All stand rds reserv

Bure u Int ational d s oids et Mesures

( PM

Inte na Bureau of Weight easu s

S a

r categories of stan rd

I ternationalStan rd

aryStand

con ndard

or Sta ard

International Std

Defi nternatio l Agre ment

Rep

closest ossible accurac attainable

Interna on St ndarr ary Std

Maintai ed Natio l Std Lab

Fu on

r ry Sta da







14/68

o SecondaryStd

o basicrefstd usedby

omeasurement calibrationlab

o inindustries

o maintainedby

oparticularindustry

o .

o Eachindustry

o ownsecondarystandard

Secondary Standard

oWorkingStd

o

ocheck calibratelabinstrument

o accuracyperformance.

Working Standard

oproc

odet correctvalues

o measurand

o comparison

ostandardones

Calibration

ostd device

ocomparison made

ostandardinstrument

o instrument isunknown

o tobecalibrated

otestinstrument

Calibration

o two methodologies

o obtaining comparison betw

otest instrument standard

instrument

oDirectcomparisons

oIndirectcomparisons

Calibrationo generatorapplies

o knowninput themeterundertest

o ratio of

ometer indicat

o knowngeneratorvalues

ogives meter'serror

o meter test instrument

o

ogenerator standard instrument

Direct Comparison

particular industry

Eac ndustry

wn secondarystanda d

accuracyperformance.

proc

e rec va s

suran

comparis

nd nes

alib tio

std de ce

omparison ade

anda instrumen

i ent is n n wn

to be l ed

testins u nt

alibra n

two methodologies

obtaining co ariso bet

es nstrument stan ar

instrument

C ib io enera orappies

nown ni put the met under test

ratio of

e indicat

re ompar n







15/68

Direct Comparison Direct ComparisonoWith of direct comparison

ogenerator also can be calibrated

o

othemeter standard instrument

o the generator

o testinstrument

Direct Comparison Indirect Comparison

o comparedwith

oresponse standardinstrument

osametype

o

oiftestinst meter

ostandard isalso

meter

oiftestinst generator

ostandard alsogenerator

Indirect ComparisonUnits (Fundamental & Supplementary)ounits

oindependentlychosen

onotdependent otherunits

es nstrument

irect Co pa on rect Co ri

compa d wit

sponse s andar nstrum

same type

es n me er

t ndard is also meterif es ge era or

standard alsog r or

ndire C p risonnit undamenta & plementary)

units

independentl chose

not epe ent eot runits







16/68

oderivedfrom

ofundamental supplementaryunits.

Units(Derived)

Units (Derived)

Units (Derived) SI Prefixes

o powersoften

osimplifiesspecification

o anyquantity

o

ofurthersimplified

o useof

prefixes

SI Prefixes SI Prefixes

s ( rived) fi

power of ten

mplifies speci ation

quant y

rther ied

use ofpr es

S r fixes I P e es







17/68

Instrument Application Guide

oSelection,care use instrument

o Beforeusing

othoroughlyfamiliarize

o itsoperation

o**readthemanualcarefully

o Select instrumentprovide

odegreeofaccuracy required

o(accuracy+resolution+cost)

Instrument Application Guideo Selection,care use instrument

o Beforeusing

o do inspectionfor

o physicalproblem

o Beforeconnecting

o to circuit

omakesure functionswitch

o rangeselectorswitch

o setup

oproperfunction range

** read the manual carefully

Select instrumentprovide

degree of ccuracy require

(accuracy+ resoluti n + cost)

to circuit

ake ure function switch

range ct switch

setup

proper functi n ang







18/68

References


ErnestDoeblin &DhaneshNManik


HSKalsi




AlanSMorris


D.V.SMurthy


References


DavidABell


CSRangan, SGSharma & VSVMani,


RKRajput,


UABakshi,AVBakshi,


AKSawhney,


References


JBGupta,


Transducers

ParametersofElectricalTransducers

Types

ActiveandPassive

AnalogueandDigital

ElectromechanicalType

Potentiometric,

Inductive,

Thermocouple,

Capacitive,

Resistive,

PiezoElectric,

StrainGauge,

IonizationGauge,

LVDT,

HallEffectSensor,

ThinFilmSensor,

ProximitySensor,

DisplacementSensor,

LoadCell,

NanoSensorsAnd

UltrasonicTransducers.

Opto ElectricalTypephotoEmissive,

PhotoConductiveand

PhotoVoltaicType.

DigitalEncoders

OpticalEncoder

SelectionCriteriaforTransducers.


Module 2 (12 hrs)

Transducers

o Transducer

o transformsenergy

ofromoneform another

o

o

omechanicalforceinto

o electricalsignal


Albert D Helfrick & William D ooper

e4. asurement & In rust mentationPrincip es:

Alan S orris

5. Transducers & Instr mentation:

D.V. S Murt y

References

6. Electronic Instrume a nd Measurements

DavidA Bell

7. In trus ment tion evice as nd Systems:

S Rangan, SGSharma & V S ani,

8. Electronic easu e ts and Instrumentation:

R Rajp ,u

9. sureme ts and Instrumentation:

U aksB hi,A V Ba ,i

10. A Course in cE t ri c a ectronic Measurements an I rus mentation:

KSawhney,

EL CTR NI INS UMENTATIONEC 010 704 S labus) 3 hours lecture and 1 hour tutorial erp week

Refer esenc

1 1. A C urse in E ectrica an E ectronic Measur ents an Instrumentati n:

J B G u t a,

LECTRONIC IN RU TI N0 710 4 Syllabus) 3 hours cte ure d 1 urh tutorialper week

Transducers

Parameters o E ectrica Transduc ser

Types

Active and Passive

Analogue nd Digital

E ectromechanical Type

Potentiometric,

LVDT,

Hall eEf ctSensor,

T in mi Sensor,

Prox iti y Sensor,

Disp cemen t Sensor,

Load Cel ,

Nano SensorsAn

ELE TRONI C RUM TE ATEC 010 704 Syl bul 3s) hours lecture hour t ut o l pe week

Modu 2le (12 hrs)

ra ducers

Tr sducer

tran orms energy

from one form another



Module 2: Transducers

of Mahatma Gandhi


mal Jyothi College of Engineering, Koovappally -


19/68

Electrical Transducers

o tomeasurenonelectricalquantities

o detector used

o converts

ophysical to displacement

o displacementactuates

o electrictransducer

o actingassecondarytransducer

o output

oelectricalinnature

Advantages of Electrical Transducers

o Electricalamplification attenuation

o

o massinertiaeffects minimised

o effectsoffriction minimised

o Controlledwith smallpowerlevel

o output

o used transmittedprocessed

o Miniaturization easily.

Transducer (General Structure)

o transducer twoparts:

o Sensing orDetectorElement

o respondsto

o changeinphysicalphenomenon &

o TransductionElement

o transforms outputofsensingelement

o to electricaloutput

o actsasasecondarytransducer

Transducer (Classification)

o

basisoftransductionformused

ii. asprimaryandsecondarytransducers,

iii. aspassive andactivetransducers,

iv. asanalogue and

digitaltransducers,

and

v. astransducers andinverse transducers

Classification based uponPrinciple of Transduction

o transducers classified basisof

o principleoftransduction

o resistive,

o inductive,

o capacitive

o how convert inputquantity

o intoresistance,inductance capacitancerespectively

o also classifiedas

o piezoelectric,

o Thermoelectric,

o magnetorestrictive,

o electrokineticand

o optical.

Classification asPrimary and Secondary Transducers

isplacementactuates

electric transducer

acting as se ondaryt ansd cer

output

el ctric in naure

Controlle wit smal power eve

output

use tra smn itte rocesse

Miniaturiza on eas y.

Transdu er (Gen al S r cture)

transd cer twopart :

Sen ins g ctorE emen

sr np s

ge in physical pheno on &

Trans uct lement

tra sfn orms outputofsensing el enm t

to lectrical output

acts asa secondarytransd eu r

ansducer (Classi tion

asis oft nsducti o m used

ii. s imary dsecondary nsd cers,

iii. spas andactive trans c rs,

iv. s nalogue ddigitaltransduc rs,

v. as trans er an invers s ucers

C ssification bas e nPrinci le ofTr sducti n

transducers assified basis of

princip e o trans uction

res st ve

n uct ve

capacitive

ow convert npu quant ty

Classi i ation asri ary a nd econdary Tr nsduce




of Mahatma Gandhi




20/68

Classification asPrimary and Secondary Transducers

o Bourdontube

o senses pressure converts

opressure into displacement

o displacementmoves core ofL.V.D.T

o converts displacementintovoltage

o Bourdontube

oPrimaryTransducer

o L.V.D.T

oSecondaryTransducer

Classification asPassive and Active Transducers

o PassiveTransducers

o derive powerfortransductionfrom

o auxiliarypowersource

o "externallypoweredtransducers".

o

Activetransducerso donotrequire auxiliarypowersourceproduce output

o selfgeneratingtype

Classification asAnalogue and Digital Transducers

o AnalogueTransducers.

o convert input into

o analogue output

o continuousfunctionoftime

o DigitalTransducers.

o convert input into

o electricaloutput

o formofpulses

Classification asTransducers and Inverse Transducers

o Transducer.

o converts nonelectricalquantity

ointo electricalquantity

o InverseTransducer.

o converts electricalquantity

o nonelectricalquantity

o E.g.;Piezobuzzer

onver s displacementinto voltage

Bourdon tube

PrimaryTrans ucer

L.V.D.T

SecondaryTransducer

ctive trans ucerso o not re e auxiliary power source produce utput

self generat ng type

Classifi i no asAnalo ue and Digit l Tran ucers

Analogue Tran cers.

conve t ut nto

ana e outpu

continuousfunct f me

Digital ransducers.

onv rt input i o

lec r output

for of ulses

Classification aransducers and Inverse Tr dn ucer

Tr sducer.

conver nonel c al uantit

o e ectr c quantity

nver e Tr d c r

c nverts electricalqua tity

nonelect uantity

.g.; Piezobuzze




of Mahatma Gandhi




21/68

Basic Requirements of a Transducer

Ruggedness

oAbility withstandoverloads

osafetystops overloadprotection

Linearity

oAbility reproduce inputoutputchara

osymmetrically linearly

Overalllinearityisthemainfactorconsidered.


Repeatability:

oAbility reproduce outputsignal

o when samemeasurand applied

orepeatedlysameenvironmentalconditions

Convenientinstrumentation:

o high analogueoutputsignal

o highsignaltonoiseratio

Digitaloutputpreferredinmanycases.


Highstabilityandreliability:

oMin error measurement

ounaffected temperature,vibration

o environmentalvariations

GoodDynamicresponse:

oOutputfaithful input

o takenas functionoftime

Theeffectisanalysedasthefrequencyresponse.

s equirements of a ans

Rugge ness

bi tl withstand overloa

sa ety s ops o r oa protect

inea y i

bili repr c input u pu chara

s metrc ly linearly

Over nearity s t ain actor onsi ere .

Basic Requir ments a ransdu r

Repeatability:

A i ity repro uce ou u signa

when same measu n app i

repeatedlysame environmental onditions

Convenient nstrumentation:

B i c e re nts of a ra sducer

Hig i ity n re iability:

Min err r easuremen

una ecte em era re, i ration

vironmental variations

Good namic response:




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ExcellentMechanicalCharacteristics:

o affectperformance

ostatic quasistatic dynamicstates

majoreffects

Mechanicalhysteresiso imperfectresponse

osensingelements

oIntegratedoverdimensions

ostrainedtransducer

Effectdependsontherawmaterialused,ageing,etc.


Viscousfloworcreep

o duetoviscousflow material

oofsensingelement

oMagnitude increases

o

increasingload temperature Materials lowmeltingpoint largercreepvalues


Elasticaftereffect

o continueddeformation

o load applied keptconstant

decreaseswithtime

oLikecreep similarrelaxationtowards

o original position

owhen load removed.

Virtuallynoresidualdeformationisobserved.


Builtinintegrateddevice

o noise,

oasymmetry

ootherdefectsminimized

Resistive Transducers

o

o measurement

ochange resistance preferred

o AC DC voltages

osuitable resistancemeasurements

Resistive Transducers

o Resistance metalconductor

Mec anica ysteresis

imper ect response

sensing lements

Integratedover dimen ons

straine trans ucer

E e ct epen s o n e a w teria used, agein , e c .

increasing oa emp ra ure tMaeria ow e tingpoint arger creep va ues

Basic Req irements f a r nsducer

Elastic aft r effect

ontin du de m tion

o ie eptco an

es wit time

Like cre p similar elaxation to a d

iginal position

ew n loa remove

Vi ua yno resi ua e ormation is ser .

s equirements of a ans

Built integrated device

noise,

asymme ry

er e ec s inimize

Resis ive Tra sdu ers

measuremen

change esistance pre re red

AC DC lvotages

suitable esistance easurements

stiv ransd cer

Res nce eta on uc rt




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Potentiometric Transducers

o POT

o

o resistiveelement with

osliding contact(wiper)

o motion ofslidingcontact

otranslatory rotational

Linear POT

Rotational POT Helipots

o combination of

oi.e.,translationalaswellasrotational.

oTheirresistiveelement formof

ohelix

o helipots.

o helical elements

omultiturn

o

canbeusedfor o translationalorrotarymotion

Helical POT Diagrammatic Representations of POTs

motion of sliding ontact

translatory rotational

otationa POT Helipots

ombination of

e. ., translationalas ell asrot ti nal.

he sr istive element f r of

o lh ix

o he oip ts.

o lh caii l e ents

multiturn

canbe used o translation r tarymotion

elical P T ia a c Re resenta on of POT




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Construction of POTs

o resistivebody

o wirewound

o thin

oplatinum nickelalloy

o wound insulatedformer

o resistanceelements alsomade ocermet

o(preciousmetalparticlesfusedintoceramicbase)o mouldedcarbon

o(mixtureofcarbon andathermosetting plasticbinder)

ocarbonfilm,

o(thinfilmofcarbon depositedon anonconductivebase)

othinmetal

o(thin,vapourdepositedlayerofmetalonglassorceramicbase)

Electrical Analysis of a POT


o

oIfdistrib of resistance

owrttranslationalmovement linear

o resistanceperunitlength

tp xR


o outputvoltage

ounderidealconditions


ounderidealcircumstances

o output voltagevaries

olinearlywithdisplacement


resistance elements also made ermet

(precious metal particlesfused into erami ase) mouldedcarbon

(mixture of arbon and the or etting p l stic binder)

arbonfilm,

(thinfilm ofcarbon epositedon a oncon uctive base)

thin metal

(thin, apour e ositedlay re ofmetal n glass eramicbase)

Electri al Analy is of a OT

Ifdisrib of resistance

ra s ationa movemen near

stanc un t engt

t

ectrical Analysis o PO

u u voltage

u er con t ni s

Electrica Analys s o POT

underide l ircumstances

ou pu voltage var sie

linearlywit isp ceme

e calA alysis o a T




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Electrical Analysis of a POT Electrical Analysis of a POT

ounderidealconditions

o sensitivity constant

o outputfaithfullyreproduced

ohas linearrelationshipwithinput


oForrotationalmotion;

oTrueforSingleTurnPOTsonly;

Potential Divider

opotentialdivider

o dividingpotential ratio

odetermined positionofsliding contact.

Potential DivideroIf resistance across

ooutputterminals infinite

o linearrelationship

o outputvoltage(eo)

o inputvoltage (ei)

o actualconditions Rm is notinfinite,

ocausesanonlinearrelationshipbetween

o output inputvoltages

Loading Effecto resistance of

oparallelcombination

oloadresistance

oportionof resistanceof

opotentiometer

nu deridealcondt o s

sensitivit const t

outpu faithfully eproduced

as i arrelatio ship ith put

Electri al Analy is of a OT

Forrotatoi na tion;

rue rSingle urn s only

Potential Divi e

potential divider

o dividng potent lia ai

etermined sition fsliding c tac .t.

Po ntial D id rIf resistance acr so

ooutputterminals infinite

o linearrelationship

output oltage (e

input oltage (e

oad g Effec r stance f

arallel ombination

o oad esist nce

opo tion of esis nce of

potentiometer




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Loading Effect

oTotalresistance

oseenbysource

Loading Effect

oTherefore,

oCurrent,

Loading Effect

oOutputvoltageunder

oLoadCondition,

Loading Effect

oRatioof

oOutputvoltageto

oinputvoltage,

ounderLoadCondition,

Loading Effect

oAs ratio Rm/Rp decreases,

othenonlinearitygoesonincreasing.

o to keeplinearity

o value Rm/Rp shouldbe

oaslarge aspossible

o

o measure outputvoltage

owith meter,

o Rp

oshouldbeassmallaspossible

Error

oading ffect

O utv lt e der

Loa ition,

Loading Effec

at o

o tOu ut voltage to

putvoltage,

du erLoad C ition,

L ading ec

oAs ratio Rm/Rp decreases

othe nonlinearitygoes on incre sing.

to keep linearity

alue Rm Rp should be

s large aspossible

rror




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Percentage Error Error Analysis

Maximum % Error Advantages of using Resistive POTs

oInexpensive

oSimple tooperate .

oUsefulformeasurementof

olargeamplitudes displacement

o efficiency veryhigh

o(Nofurtheramplificationneeded)

oExcellentFrequencyResponse

o(ExceptWirewoundtype)

oExcellent Resolution(ExceptWirewoundtype)

Disadvantages of using Resistive POTs

oLinearpotentiometer

o largeforce move wiper

oSlidingcontacts

ocontaminated

owearout

o misaligned

ogeneratenoise

o(thelifeofthetransducerislimited).

Strain Gauge

oIf metalconductorstretched ompressed

o resistancechanges

o(bothlengthanddiameterofconductorchange)

o changein valueof

oresistivity

owhen strained

o(piezoresistiveeffect)

o resistancestraingauges alsoknown

oPiezoresistivegauges

aM ximum Err v ages of using Res ts ive

In pensive

Si le o operate

lformeasureme tof

rg plitu s displacemen

eff i ncy very high

o rheram ication needed)

xc equency esp nse

(Except ire n e)

xcellent Resolutio (Exc pe t er o ndtype)

Disadvantage of usin Re istive Ts

Linear potentiometer

arge force ove wip re

Sliding contacts

o ontaminated

owear out

o misaligned

generate noise

Stra Gauge

If eta onductorstretc edh o ressed

resist ca e changes

bot engt a iam er o conductor change

ange in value o

esist y

when strained




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Strain Gauge

oStraingauges measur

ostrain associatedstress

oin stressanalysis

o otherdetectors transducers

oloadcells,

otorquemeters,

odiaphragmtypepressuregauges,

otemperaturesensors,

oaccelerometers

oflowmeters

oemploystraingaugessecondarytransducers

Principle of Strain Gauge

Principle of Strain Gauge Principle of Strain Gauge

o gauge

osubj to positivestrain

o lengthincr

o

o area crosssection decreases

o resistance

oprop to length

oinv prop to area crosssection,

o resistance gauge

oincreases positivestrain

Peizo-resistive Effect

o change resistance

ostrainedconductor

omore than

o increaseinresistance

odue todimensionalchanges.

o extrachange valueofresistance

o attrib to change value

oresistivityof conductorstrained

Strain Gauge

o Resistance UnStrained(Strain)Gauge

torque meters,

iaphragm type pressure gauges,

otemperature sensors,

ccelerometers

oflowmeters

employ strain auges cse ondarytransduce s

Princ ple of St in uge r nciple of Strain uge

gauge

o bs j to positive strain

length incr

o

re cross e t on ecreases

o es ti ce

to engt

o nv pr to er a crosssection,,

esistance gauge

o ncreases positive s ain

Peiz -o resistiv E ect

change er sistance

strained conduct r

more than

increase in resistance

Stra Gauge

Res nce Un Straine train)Gauge




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Working of Strain Gauge

ostrain expressed

omicrostrain.

o1microstrain 1m/m.

o changein value resistivity material

owhenstrainedisneglected,

othegaugefactor

Working of Strain Gauge

Types of Strain Gauge

Unbondedmetal

Bondedmetalwire

Bondedmetalfoil

Vacuumdepositedthinmetalfilm

Sputterdepositedthinmetal

Bondedsemiconductor

Diffusedmetal

Major Applications of Strain GaugeoStraingauges usedfor

otwomajor applications

(i) Expstressanalysis

o machines

o structures

o

Construction

o force

o torque

o pressureflow

o accelerationtransducers

Unbounded Strain Gauge Unbounded Strain Gauge

t egauge actor

Ty ep s of Stra n G ge

Unbond dme

Bondedmeta ire

on e me oi

Vacuu epos tedthin metal il

putte dep ted thin metal

onde semiconductor

D fuse metal

a pplications of r intr na gauges use o

t major pplic iat ns

x stress ana sly s

m ines

rs uc s

Con rt uc

orque

pressureflow

cceleration trans cers

Unbou ded Str n auge und Strain au e




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Unbounded Strain Gauge

o unboundedstraingauge

o wirestretchedbetweentwopoints

o insulating medium

o wires madeof

ocoppernickel

ochromenickel

onickeliron alloys

o element connectedvia rodtoadiaphragm

o usedsensingpressure

o wires tensioned avoidbuckling

o

Bounded Strain Gauge

Bounded Strain Gauge Bounded Strain Gauge

Bounded Strain Gauge Bounded Strain Gauge

o bondedstraingauges used

ostressanalysis

o constructionoftransducers

o consistsofgridof

ofineresistancewire

ogrid cemented carrier

o thinsheet

opaper Bakelite Teflon

o wire covered top

o thinsheet material preventfrom mechanicaldamage

ospreading wirepermits

o uniformdistribution stress

chrome nickel

nic e iron a oys

e ement onnecte via ro toa iap ragm

use sensing pre ure

ires tensione avoi uc ing

Bou ded Str n G ge ounded Strain e

Boun ed Stra G uge nde train aug

onded strain gauges us

stress a sis

on rs uctio o trans ers

consists o rig o

ine resist can e wire

gri cemente arrier




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oForexcellent reproducibleresults

straingauge

o high gaugefactorGf resistance

oashigh aspossible


Bounded Metal (Foil) Strain Gauge Metal (Foil) Strain Gauge (Spiral)

Metal (Foil) Strain Gauge(X, Y & Z Axes Elements of an Accelerometer

Hookes Law

as ig aspossi e

Bounded etal (Fo ) Stra n Gauge e oil) Strain Gau (Sp r

Meta Foil)S rain Gauge(X, Y & Z Axes E ents of nAccelerome

H es L




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Semiconductor Strain Gauge Advantages of Semiconductor Strain Gauge

oHighgaugefactor 130

o(Measureeven0.01microstrain).

oExcellenthysteresischaracteristics.

o(10x106 operations)and

o(frequencyresponse upto 1012 Hz);

oVerysmallinlength

o(0.7to7mm).

o(Veryusefulformeasurementof localstrains).

Rosette(Application Specific Strain Gauge)




(> 10 x 106 operations )and

( requ nce y response up o 1012 Hz ;

erV ysma in engt

(0.7 o 7 m).

Very useful for measur ment f localstrains).

tte(Appli ati n S c fic S rt n Gauge)

Roset(Application Specific St in G e)

osett (Applicatio Sp ific St ain Gauge

sette( pplicat n Specific S rain uge)




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Capacitive Transducers

oProximityTransducers.

oDisplacementTransducer.

oNonloading,

oNoncontact,and

oNoninvasive

Capacitive Transducers

o

o parallelplatecapacitor

d

AC r

owhere,

o0=absolute permittivityoffreespace

or=dielectricconstantofthemedium betweentheplates

(relativepermittivity)

oA=area oftheplates

od=distance ofseparationbetweentheplates

Properties of Some Dielectric Materials Capacitive Thickness Transducer

oplates arranged

osheet

o passed between plates

owithouttouchingthem

Capacitive Thickness Transducer

owhere:

oa totalseparationbetween plates

otthickness of thesheet

oCapacitanceoftheSystem:

Capacitive Thickness Transducero increase in

o thickness sheett

ocauses an increase of

othecapacitance byC,andhence

oSolvingforC/C0

owhere:

oN=SensitivityFactor

Nonloading,

Noncon ac , n

on nvas ve

,

olutepermittivityoffreespace

r= dielectri constant f the medium between the plates

(relativepermitti ity

A = rea fth l tes

d= istanc ofseparation betw n theplate

Properties o Some lect i Materials a c tive Thickness r nsd

ates rrange

sheet

passed b t een plat

wit out tou ng t em

Capacitive hickne s T nsduce

w ere:

Capacitance of the stem

p i i e Th nessTran ucer crease in

o thickness sheet t

o auses a increa e of

the cap ia tance byCand hence




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Capacitive Displacement Transducer Capacitive Displacement Transducer

oIf airgap decreased x,

othecapacitance increasesbyC

owhere,

Capacitive Displacement Transducer(Using Movable Dielectric Core)

Capacitive Proximity Transducer

Capacitive Proximity Transducer

oTheOutputSignal,

where:

Capacitive Strain Transducer

here,

CapacitiveDisplace ent T nsducer(Usin abl Dielectrc Core)

pacitive Proximity T ansd e

Capacitive roxi y Tr nsducer

The OutputSigna

C p itiv train Tr na sdu er




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Peizo-Electric Transducers Peizo-Electric Transducersosymmetricalcrystallinematerials

o Quartz Rochellesalt Bariumtitanate

oproduce emf

owhen placedunderstress

o peizo electrictransducers

o

acrystalplacedbetweensolidbaseoforcesummingmember

oconversely varyingpotential

o properaxisof crystal

o change dimensions

oof crystal

odeformingit

Peizo-Electric Transducers

o two maingroups piezoelectric crystals

oNaturalcrystals

o (quartzandtourmaline).

oSyntheticcrystals

o(Rochellesalt,lithiumsulphate,

odipotassium tartrate etc).

Desirable Propertiesof Piezoelectric Materials

Stability.

Highoutput.

Insensitivitytotemperatureandhumidity.

Theabilitytobeformedintomostdesirableshape

Natural vs. SyntheticPiezoelectric Materials

Advantages

Naturalcrystals:

(i)Highermechanicalandthermalstability.

(ii)Abilitytowithstandhigherstresses.

(iii)Lowleakage.

(iv)Goodfrequencyresponse.

Syntheticmaterials

ohaveahighervoltagesensitivity.

Working Principleof Piezoelectric Materials

oThemagnitude andpolarityof

otheinducedchargeon thecrystalsurface is

oproportionalto

othemagnitude anddirectionof

otheappliedforce.

a crystal placed between solid base rcesumming ember

no verse y varying potentia

pro rp xis o r tal

ang dimensio s

f crystal

e rming it

Peizo- lectric ans cers

wo ma roups iezoelectric crystals

Natur l r s

ua za tourmaline .

Syn et cti sta s

oc e s t,lithium sulphate,

dipota sium tartrate etc).

s rable Prop tiesof Piezoelectric Ma et rials

ta ility.

Hig put.

Ins siti t to e perature and h ty.

Th bility e ormed nto mos desira l shape

atu al s. S eticPiezoele trc Materials

dvantages

Natural crystals :

(i) Higher mechanicalandt rmal st bility

(ii) Ability to withstand higher stresse .

r in rinc ofPi oelectric Ma erials

The magniut de andpolar t of

the indu ed cha e n the crystalsurface is

prop ro tional o

the magnitude anddirection of




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Working Principleof Piezoelectric Materials

oThecharge attheelectrode

ogivesrisetovoltage(E),givenby,

oWhere;

Advantages & Disadvantagesof Piezoelectric Transducers

Proximity Sensors

oproximitysensorconsistsof

oanelementthatchanges eitheritsstate

oorananaloguesignal

owhen itisclose toanobject.

o(oftennotactuallytouching)

oMagnetic,

o capacitance

oinductance

oeddycurrent

o

Proximity Sensors

ophotoemitterdetectorpairrepresentsanotherapproach,

owhereinterruptionorreflectionofabeamoflight

oisusedtodetectanobjectinanoncontactmanner.

oE.g.,(LED&phototransistor/photodiodecombination

oCommonapplicationsforproximity

:

oCountingmovingobjects

oLimitingt traverseof mechanism

Eddy Current Proximity Sensor Eddy Current Proximity Sensor

o coilsuppliedwith a c

o alternatingmagneticfieldproduced

oIf metal in closeproximity

oto magneticfield

oeddycurrents inducedinit

o eddycurrents produce amagneticfield

o distorts themagnetic responsiblefortheirproduction

o impedanceofthecoilchangesandso

otheamplitudeofthealternatingcurrent.

ere;

Proximity enso

proximitysenso no sistsof

an le ent hanges eit rh itsstate

r nao uesigna

ew s c ose o an ject

o n actually touching

Mag etn ic,

capacitance

i uct nce

e y rre

Proximity Sens r

p to emitterdetector pair pe resen ot er pproach,

eh re interruption or refle oti n of a be m gh

s use o e tect o j c n co n r.

.g., D & p t a sistor photodiode om aton

Com pplications roximity :

Coun ving o j te s

Limiting rav e ec anism

Eddy Cur ent Pro mi Sensor E urre Proxim y sor

coil pplied with c

alternating m neticfield produced

If metal close prox m y

oto magnet fi d

o ddycur nre ts induced in it

e y ents produce a magnetic field

istorts the a netic res onsible or their roduction




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Advantages ofEddy Current Proximity Sensor

Smallinsize.

Relativelyinexpensive.

Highflexibility.

Highsensitivitytosmalldisplacements.

Capacitance Proximity Sensor

Capacitance Proximity Sensor

o consistsofsimpleplate

o

owith object(earthed)

o as otherplate

oAs objectapproachessensor

oseparationbetw plate

o andobjectchanges

o significant

oas object closeto sensor.

Hall Effect

Hall Effect Transducerso"Whenanyspecimen

ocarrying acurrentI

oisplacedinthe

otransversemagneticfieldB,

othenanelectricfieldEisinducedinthespecimen

ointhedirectionperpendicularto bothIandB.

ThephenomenonisknownasHalleffect".

Hall Voltage

oCurrent in Ntypespecimen

o carried byelectrons

o electrons,as result Halleffect,

oaccumulate side1

o getsnegativelycharged

orelativeto side2

oConsequently potentialdifferencedevelops

obetween 1 2

o called 'Hallvoltage'(VH).

Hig sensitivity to smal displace ts.

apaci ance ro m t y ensor

consists ofs le plat

wi ect earthed

s other plate

s o ject roaches sensor

sepa ation etw plate

and objectch ges

sgn c t

as ject los to sensor.

all E t

Hall Effect T ans cers"When anyspecimen

carry ng currentI

isplaced in the

ransverse magnetic e B

al oltag

urre n ypespec en

carried yeectrons

electr no s, as r ult Hall effect,

ccumu e side 1

ets ne ativel char ed




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Hall Voltage

oHallvoltageinanNtypesemiconductor

o ispositivesurface2

oOntheotherhand,

o Ptype

o

opositive surface1

Hall Voltage

o magnitude Hallvoltage(VH)

oWhere;

Uses of Hall Effect Halleffectmaybeusedfor:

1. Determining

o NtypeorPtype

2. Determining carrierconcentration

3. Calculating mobility

o (havingmeasuredtheconductivity).

4. Magneticfieldmeter.

oTheHallvoltageVHforagivencurrent

oisproportionaltoB.

o VH

omeasures themagneticfieldB.

Uses of Hall Effect

Halleffectmultiplier.

oTheinstrumentgivesanoutput proportionalto

otheproductoftwosignals

o ifcurrentIismadeproportionaltooneinputand

oifBisproportionaltosecondinput

o HallvoltageVHisproportionalto

otheproductofthetwoinputs

Hall EffectDisplacement Transducer


o measure lineardispl or

o locate structuralelement

oincaseswhereitispossibleto

ochangethemagneticfieldstrength

o byvariationin thegeometryof

oamagneticstructure.

Ptype

positi e surf e 1

here;

Us s of Ha l Eff ce t Ha ect u e or

1. Dete ir ni

N yp or ype

D2. ete minin arrier concen tion

3. Calc ating o ility

aving sure t e con uctivity).

4. Mag etic iel me er

TheHall oltage VHforagive urrent

i proport onalto B.

me su e mag tne ci ie B.

ses of Hall E ce t

a e ect mu tip ier

einstrument giv s n ou pu propor ni a

t roduc o two signals

f r Iis madeproportional o ne npi utand

iBisproport a o secon nput

a vo t is roportio a o

thepro uct et two i ut

Hall Effe Displace e Tra sducer

all fectsp a ment Transducer

easure inear displ r

ocate trs uct al eleme

in cases where it possible to

c a e the magnetic iel strengt

by variation in thegeometry o




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oTheHalleffectelement locatedingap

oadjtopermanentmagnet

ofieldstrength ingap

oduetopermanentmember

o changedbychanging

oposition offerromagneticplate

oThevoltageoutput Halleffectelement

oprop tofieldstrength

oin gap functionoftheposition displacement

oof ferromagneticplate

owithrespecttostructure.

Hall Effect Fluid Level Transducer

Hall Effect Fluid Level Transducer

o magnet attachedtofloat

oas level changes

o floatdistance

ofrom Hallsensorchanges

o result Hallvoltageoutput

o ameasureof

o distanceoffloatfrom

osensor hence level

oofthefuelin tank

Variable Inductance Transducers

o

o change magneticcharacteristic

oof electricalcircuit

oin responseto measure

o

odisplacement,

ovelocity,

oacceleration

Types of Variable Inductance Transducers

1. Selfgeneratingtype.

o voltage isgenerated becauseof

o therelativemotion between

o aconductorandamagneticfield.

o classifiedasfollows:

Electromagnetic

Electrodynamictype.

Eddycurrent

Passivetype

o motion ofanobjectresults in

ochangesintheinductance ofthecoils

oofthetransducer.

classified

Variablereluctance.

Mutualinductance.

Differentialtransfer

Types of Variable Inductance Transducers

o changed y hanging

oposition of ferromagnetic plate

oThe oltage output Hall effectelemen

prop to field strength

in gap function fthe position splacement

offerromagneticplate

with espec o structure.

Hall E fect luid Le el Transducer

magne at ed to fl ao t

as leve chan e

t distance

from Hall sensorcha es

re ult Hall voltage ou p

a measure o

distance offlo t rom

sor ence level

o el in ta k

a e Inductance T sdu

c ange ma etic chara sti

o electr lcircuit

in res onseto measure

d sp ent,

velocity,

acceleration

Types of Varia le Induc nc Transdu rs

1. Self generat ng type.

voltage isgener ted becau e of

the relative motion etween

a conductorand a magnet ield.

ass ype

moti n o an objectr sults n

chan es n th i ductance ofthe coils

o he transducer.

classified

pes able I uctanc Tr sducers




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Electro-Magnetic Type (Active) Electro-Magnetic Type (Active)

Electro-Dynamic Type (Active) Electro-Dynamic Type (Active)

Eddy Current Type (Active) Eddy Current Tachometer (Active)

Electro- ynamic ype( ctive) ro-Dynamic Typ Acti e

Eddy C rentT e ctive) d rent achome er ctive)




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LVDT Type (Passive) LVDT Type (Passive)

Pressure Measurement using LVDT Advantages of LVDT

Disadvantages of LVDT Ultrasonic Transducers

o ultrasonicdetectors

opiezoelectriccrystals

oQuartz commonly used

o(freq range 200kHz 300kHz)

Pressure easurem nt us g LVDT dvantages of L T

Disad ntage s f L DT son ransd cer

ultrason detectors

piezoel ctric rysta

Q artz commonly used

eq range 200 kHz 300 kHz)




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Applications of Ultrasonic Transducers

oTypicalapplication

o Flowmeasurement

oLevelmeasurement

oThickness measurement

oNondestructive testing materials.

Ultrasonic Flow Meter

Ultrasonic Flow Meter

oWhenultrasonicpulses transmitted

oacross thefluid

othevelocityof ultrasonicwaves

oisincreasedor

odecreasedby

othefluidvelocity

odependingupon

odirection ofthefluidflow

Ultrasonic Flow MeteroLetfluidvelocitybevm/s.

o(assumethatthefluidisflowinginthepipefrom

olefthandsidetorighthandside)

oVelocityof ultrasonicsignalfrom transmitterAto

o receiverA increasedto avalue(c+vcos),

owhere :

ocisthevelocityofsoundthroughthefluidinthepipe, and

o istheanglebetweenthepathofsoundandwallofthepipe.

oLetlbethe

distance(oblique),

between transmitterandreceiver

o timetakenbypulsesignaltogo

ofromtransmitterA toreceiverA willbe

oThen,repetitionfrequencyofthereceivedpulseatA,

Ultrasonic Flow Metero

o velocityof ultrasonicsignaltransmittedby

o transmitterBandreceived bythereceiverB

o reducedbyfluidvelocity

oitspulserepetitionfrequency,fB :

oThedifferenceinfrequencyisgivenby:

Ultrasonic Level Measurement

Thickness measurement

Nondestructive testing materias.

Ultr sonic w er

When ultr so lses ransmitted

across the

the ve of ultras icwaves

is sed or

reasedby

thefluid velocity

epen ngupo

irectio of t e uid flow

trasonic Flow ter luid velocity e m/ .

sa t at t e uid is owing in t e ppi rom

e t a n s i e to r ig t a n s i e

Ve c f ultrasonicsignalfr transmitterA to

r c ver increasedto value ( + v c os ,

re e :

is the veloc f oundthrough thefluid n the , n

s t e n e et t epat o soun an a o t ep pe

o et bethe di ance (oblique etw en transmitter and e iver

o t a bypulsesigna togo

ofrom transmitter t c iv rA illbe

Then repetitionfrequency f et rec ve dpulse tA

Ultras nic Flo ter

ve oc tyo u trasonics gna transmitte y

transm tterBandrece div y the rece ver

educedbyfluid ov city

ts pu se repet t on requency,fB :

e in frequ s g ven y:

l r s icL el Mea ure ent




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Ultrasonic Non Destructive Testing

oUltrasound propagated

ointopieceunderinspection

o absenceofflaw

o transduceroutput constant

o anyirregularity

osuchas existenceofacrackorforeignobject

o somereflection of

otransmittedultrasonicwave

Advantages & Disadvantages of Ultrasonic

oAdvantages:

oInsensitive to

oviscositypressure temperaturevariations

oBidirectionalmeasuringcapacity

oGoodaccuracy

oFastresponse

oNondestructivemeasurement

oWidefrequencyrange.

oSystemisversatile

o canbeusedforanypipesize

oDisadvantage:

oCostishigh.

Photo-Electric Transducers

oPhotoelectricdevices categorisedas

ophotoemissive,photoconductive photovoltaic.

ophotoemissive

oradiationfallingon cathode causeselectrons tobeemitted

ofrom thecathodesurface.

ophotoconductive devices

o resistanceof material changedwhenitisilluminated

oPhotovoltaiccellsgenerate outputvoltage

oproportionalto theradiationintensity

oTheincidentradiationmaybe

oinfrared,ultraviolet,gamma rays,Xrays, orvisiblelight.

Photo Multiplier Tube

Photo Multiplier Tube

oConsistsof evacuatedglassenvelope

ocontainingaphotocathode,ananode and

oseveraladditionalelectrodes,termedDynodes

oWhenelectrons movingatahighvelocitystrikeanappropriatematerial

o materialemitsagreaternumberofelectrons

othan itwasstruckwith

Photo Conductive Cell (LDR)

nyirregularity

such s existence of crack orfor gn obje t

some reflecti of

transmitted ultr sonicwav

Fastresponse

nN structive measurement

Wi e reque cy range.

System s ersatile

an e use rany pipe si

advantage:

Costis ig .

P oto lectric ans cers

Photo electri dev es ate risedas

p oto iss p to on uc vt e p otovo taic

hoto ie ss ve

diatoni fa on athode cau ss lectrons tobe emtt

from t ode surface

photo nc d v devices

re istance aterial hangedw e t lumi tn d

Photo vol it c ellsgenerate outputvola e

rop p torionalto the radiation nte sty

e nci e t a iation may e

nfrared ult let ,gamm rays,X ayr s, rvisible ight.

oto Multiplier be

Photo ultipl er be

onsists of evacuatedglass envelope

conta n ng p o to c at o e ano e an

severa a t o na e ct ro e s t er me no es

P o ond ctive Ce ( R)




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/

Photo Conductive Cell (LDR)

oElectricalresistance ofthematerialvaries

owith theamountofincidentlight,

ophotoconductive material

o Cadmiumsulphide Cadmiumselenide

o Cadmiumsulphoselenide

odeposited in zig zag pattern

o(toobtainadesiredresistancevalueandpowerrating)

oseparatingtwometalcoatedareasactingaselectrodes

oonaninsulatingbasesuchasceramic

oTheassemblyisenclosedin ametalcase

owithaglasswindow

ooverthephotoconductive material.

Photo Diode

oA reversebiasedsemiconductordiodepasses

oonlyaverysmallleakagecurrentifthejunctionisexposedtolight.

oUnderilluminationthecurrentrises

oindirectproportion to thelightintensity.

Photo Transistor Solar Cell

Digital Encoders Digital Encoders

o employsgratingprinciple

otwoglassdisks onefixed,theotherrotating

owithidenticalopaque/clearpatterns

ophotographicallydeposited

oaremountedsidebysidewithabout

o250mclearancebetweenthem

oParallellightisprojected throughthetwodisks

otowardphotosensorsonthefarside.

oWhenopaquesegmentsarealigned,

oaminimum(logical0)signalisproduced,

owhile alignmentofclearsegments

ogivesamaximum(logical1)signal.

epos te n z g zag pattern

(to btain a desired resistance value and power rating)

separat ngtwometa oate reas ct ngas ectro es

insu ating ase c eramic

The ssembly s nclosedin a metal ea

wit ag ass win ow

v t ep oto con uct ve ma aer .

ase se con uctor o e asses

only a ery lsm l leakage curren the unction is exposed to ight.

n eri uminationt e rcur en r ses

n directproport on to the g t n te tns y

P oto Tra sisto Solar Cell

Di ita Enc der igit ncode s

empoys t ng pr nc p e

wog ass is s xed,t e o t e r ar t ng

with idenicat l qop ue/clearpatt nser

p ot rao p ica epo es

te si e y s i ewit a out

250 clearance between them

Para e g t spro ecte t roug t e wo s s




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References


ErnestDoeblin &DhaneshNManik


HSKalsi




AlanSMorris


D.V.SMurthy


References


DavidABell


CSRangan, SGSharma & VSVMani,


RKRajput,


UABakshi,AVBakshi,


AKSawhney,


References


JBGupta,


IntermediateElements

InstrumentationAmplifier,

IsolationAmplifier,

Opto Couplers.

DCandACBridges:

WagnerGroundConnection.

DataTransmissionElements

(AnalogAndDigital).

FDMTDM:


Module 3(12 hrs)

Instrumentation Amplifiers(Significance)

oInmostInstrumentationcases:

oTransduceroutputsare;

Verylowlevelsignal

Notsignificantto

drivethenextstageofthesystem.

oTransducersare mountedremotefrom controllocations

Longcablingneeded,

Signalissusceptibleto;

Noise&AtmosphericInterference,

o

Before

next

stage

its necessary

toAmplifysignallevel,

Reject noise &interference.


Albert D Helfrick & William D ooper

e4. asurement & In rust mentationPrincip es:

Alan S orris

5. Transducers & Instr mentation:

D.V. S Murt y

References

6. Electronic Instrume a nd Measurements

DavidA Bell

7. In trus ment tion evice as nd Systems:

S Rangan, SGSharma & V S ani,

8. Electronic easu e ts and Instrumentation:

R Rajp ,u

9. sureme ts and Instrumentation:

U aksB hi,A V Ba ,i

10. A Course in cE tri c a ectronic Measurements an I rus mentation:

KSawhney,

EL CTR NI INS UMENTATIONEC 010 704 S la bu s) 3 hours lecture and 1 hour tutorial erp week

Refer esenc

1 1. A Curse in E ectrica an E ectronic Measur ents an Instrumentati n:

J B G u t a,

LECTRONIC IN RU TI N0 710 4 Syllabus) 3 hours cte ure d 1 urh tutorialper week

Intermediate lements

Instrumentation Amplifier,

Isolation Amplifier,

Opto Couplers.

WagnerGroun onnection.

Data Transmis nsi Elements

ELE RC ON INS RUMEN TIONEC 010 704 Syllabu 3s) hours lecture and 1 hour torialper week

od eu 3(12 hrs)

n t u entat n Amp ersgnif cance)

Inmos In umentation as :e

Transducer tputs re

Very lo level s nal

Notsig fn icantto

riv the nextstage of the system.

ansducers re mounted remotefrom control ocations



Module 3: Intermediate Elements

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Instrumentation Amplifiers Instrumentation Amplifiers (Features)

oThemajorrequirementsof instrumentationamplifier

oHigh CMRR

oHigh InputImpedance

oLowDrift&Noise

oModerate Bandwidth

oLimitedGain(11,000)(Programmable byR1)

oHighCMRR realizedbyconnecting

otwononinvertingconfigurations

owithopamps,1 and2

ohaving common feedbackresistorR1

Instrumentation Amplifiers

oSince theopampinputscarrynocurrent

oasinglecurrentiflows

ofrom e01 toe02 through

oR2,R1,andR2,giving:

oGainofanInstrumentationAmplifier:

ee

eA

Limitation of Instrumentation Amplifiers

oRequiresareturnpathforbiascurrents.

oIfnotprovided,theywillchargestraycapacitances;

ocausingoutput todriftexcessively/saturate.

owhenfloatingsourceslikethermocoupleareamplified,

oaconnection toamplifiergroundmustbeprovided,

owhichleads toexcessivenoise.

oIsolationamplifierdoesntrequiresuchagroundconnection

o(SignalisIsolatedfromGround)&

oRejectionofInterference NoiseisImproved.

Isolation Amplifiers

oSpecialsubclassofInstrumentationAmplifier:

oIntendedforusewhere:

Lowlevelsignalride ontopof

ohighcommonmodevoltage.

Possibilitiesexistsof

otroublesomegrounddisturbances&groundloops.

Processing circuitrymustbeprotectedfrom

ofaults &powertransients.

Interferencefrom

omotor,powerline...etc.isheavy.

Patientprotectionin

oBiomedicalapplications.

Coupling Techniques used in Isolation Amplifiers

Optical

Coupling

Transformer

Coupling

Li ite Gain 1 1,000 rogramma e yR1

Hig RC R rea ize y onnecting

wo noninv rti onfigurations

ith p mps 1 n 2

having com on feedba kresistorR1

Instru entatio Amp fiers

oSince he opamp uin ts rc y urrent

oasingle curr nte iflows

ofrom 1 to e02 u h

R2, R1, a ,giving:

o ain f an stI mer ntation Amplifier

eA

L it n of Instrumentat Am er

equ sr re urnpat or as urren s

n pro vi e , t e y wi arge s r y apac tance

causing output to drift xce vss lysaturate.

oating r i e t e rm o o p e r amp e

onnc t on to ampli iergr u must epro v e

hic dle s to exces veno se.

o lI ation mpla ifier o n e iresuch groundconnection

Sign is Iso ate ro ound &

o ejectio o Interfer ce Noise is Improved.

Isola ion A if rs

Specialsubclass strumen ation mplifier

Intended foruse here:

Low evel signalride n to of

highcommon modevoltage.

Possibilitiesex sts of

otroublesome ground isturbances ground loops.

uCo li g T nique s sed in Isol tion mpl fiers

rans ormer

oup ng



Module 3: Intermediate Elements

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Current Telemetry Systems

oWhen pressure systemchanges

o bourdontubemovessliding contact

o changing currentat transmittingterminal.

Motion BalanceCurrent Telemetry Systems

Motion BalanceCurrent Telemetry Systems

opressure on bourdon tubecauses

o displacement core of

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