Inductive Transducers.pdf

GENERAL VIEW ON Inductive Transducer-MUKESH SUNDARARAJAN

1. INDUCTIVE
TRANSDUCER
Mukesh Sundararajan

2. Inductivetransducersworkontheprincipleofinductance
changeduetoanyappreciablechangeinthequantitytobe
measuredi.e.measured.Forexample,LVDT,akindofinductive
transducers,measuresdisplacementintermsofvoltage
differencebetweenitstwosecondaryvoltages.
InInductivetransducers,thebasicprincipleisthatself-
inductanceofasinglecoilorthemutual
inductancebetweentwocoilsischangedbyaquantitytobe
measuredi.e.measurand.Usually,themeasurandcouldbea
rotaryorlineardisplacement,force,pressure,torque,velocity,
acceleration,andvibration.
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Introduction

3. ClassificationofTransducers
SelfGenerating Non-SelfGenerating
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4. Self-Generating
Transducer
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A voltage signal is generated in the
transducer, because of relative
motionoftheconductor anda
magneticfield.
EXAMPLE:
1.ELECTRODYNAMIC
2.ELECTROMAGNETIC
3.EDDYCURRENTTYPE,etc

5. Non-SelfGenerating
Transducer
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Also called as external power
source oftransducers, in which
an external source isneeded to
energizecoils,theinductance
of which would change due to
motionoftheobject.
Exapmle:
1.LVDTtype
2.Airgaptype
3.Attachmenttypeinductance
transducer,etc.

6. CarrierSupplyandBridge Output
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7. MainWorkingPrinciple
Theworkingprincipleofaninductivetransduceristhemagnetic
material’sinduction.Justliketheelectricalconductor’sresistance,
itdependsonvariousfactors.Themagneticmaterial’sinductioncan
dependondifferentvariableslikethetwistsofthecoiloverthe
material,themagneticmaterial’ssize,&theflux’spermeability.
Themagneticmaterialsareusedinthetransducersinthepathof
flux.Thereissomeairgapbetweenthem.Thechangeinthecircuit
inductancecanbeoccurredduetotheairgapchange.Inmostof
thesetransducers,itismainlyusedtoworktheinstrumentproperly.
Theinductivetransducerusesthreeworkingprincipleswhichinclude
thefollowing.
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8. SelfInductanceChange:
•Weknowthatthecoil’sself-inductancecanbederivedby
L=N2/R
‘R’isthemagneticcircuit’sreluctance
•The reluctance‘R’canbe derivedbythefollowingequation
R=l/µA
•Thus,inductanceequationcanbecome likethefollowing
L=N2µA/l
Where
•A= ItistheCoil’s cross-sectionalarea
•l=Coil’slength
•µ=Permeability
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9. •WeknowthatgeometricformfactorG=A/l,thentheinductanceequation
willbecomelikethefollowing.
L=N2µG
EddyCurrentProduction:
WheneveraconductingshieldislocatedclosetoacoilcarryingAC(alternating
current),thenthecurrentflowcanbeinducedwithintheshieldwhichisknownas
“EDDYCURRENT”.Thiskindofprincipleisusedininductivetransducers.
WhenaconductingplateisarrangedneartoacoilcarryingACtheneddycurrents
willbegeneratedwithintheplate.Theplatewhichcarrieseddycurrentwill
generatestheirownmagneticfieldwhichworksagainstplatemagneticfield.So
themagneticfluxwillbereduced.
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10. InductiveTransducer
Applications
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⦿Theapplicationofthesetransducersfindsin
proximitysensorstomeasureposition,touchpads,
dynamicmotion,etc.
⦿Mostlythesetransducersareusedfordetectingthe
kindofmetal,tofindmisslostpartsotherwisecounts
theobjects.
⦿Thesetransducersarealsoapplicablefordetectingthe
movementoftheapparatuswhichincludebeltconveyor
andbucketelevatoretc..

11. InductiveTransducer
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Advantages:
•Theresponsivityofthistransducerishigh.
•Loadeffectswillbereduced.
•Strongagainstecologicalquantities.
Disadvantages:
•Theoperatingrangewillbereducedduetosideeffects.
•TheworkingtemperatureshouldbeundertheCurietemperature.
•Sensitivetothemagneticfield.

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