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    RESISTANCE

    THERMOMETER 

      By: Shashank

    Pathak 

      EN – 4th Year 

    1

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    Outline Of The Talk 

    Basic introduction

    Construction

    Characteristics of material used in R.T

    Tyes of aro!imations

    "d#anta$es % &imitations

    "lications 'n $oin$ research on R.T.()s

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    RT / RTD

    Basically the resistance of a conductor chan$es *hen

    its temerature is chan$ed.This roerty is utili+ed for

    measurement of temerature.

      'R 

    Resistance thermometers, also called resistance

    temperature detectors -RTDs, are sensors used to

    measure temerature /y correlatin$ the resistance of

    the RT( element *ith temerature.

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    https://en.wikipedia.org/wiki/Sensorhttps://en.wikipedia.org/wiki/Sensor

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    Construction

    0ost RT( elementsconsist of a len$th of

    fine coiled *ire

    *raed around a

    ceramic or $lass core.

    The element isusually 1uite fra$ile,

    so it is often laced

    inside a sheathed

     ro/e to rotect it.

    The RT( element is

    made from a ure

    material, tyically

     latinum, nickel or

    coer 

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    Reuirements Of Material To !e "se In RTD

    2. The chan$e in resistance of material er unit

    chan$e in temerature should /e as lar$e as ossi/le.

    3. The material should ha#e a hi$h #alue of

    resisti#ity so that minimum #olume of

    material is used for the construction of RT(.

    .  Nickel , coer and latinum are /est suited.

    Platinum is used no*adays

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    Characteristics Of Materials "sed #or

    RTD

    Graph ofresistance vstemperatureof materials

    like nickel ,copper &platinum hasbeen shown &

    linearityproperty hasbeenobserved.

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    T$pes Of Appro%imations In RTD

    LINEAR APPROXIMATION :

    !n e"uation can be developed for

    strai#ht line which appro$imates theresistance % temp. 'urve over aspeci(ed span.

    )

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     0athematically it can /e *ritten as,

    R56 R5 -27ₒ

    *+5 8ith 52959538here, R56 "ro!imate resistance at 5;c

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     &"ADRATIC A''RO(IMATION )

    ?t is more accurate reresentation of cur#e o#er a

    limited ran$e of temerature. This relationshi includes /oth a linear term and

    an additional term *hich #aries as the s1uare of

    the difference in the temerature.

    ?t is $i#en /y :

     R56 R5 @27ₒ *1 57 *2 5A3

     *here 2 6linear fractional chan$e in resistance D ;c

     *2 / "uadratic fractional chan#e in resistance D-;c A3

     

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    Ad*anta+es

    &inearity o#er a *ide oeratin$ ran$e.

    i$h accuracy

    &o* drift

    8ide oeratin$ ran$e

    Suita/ility for recision alications.

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    ,imitations

    RT(s in industrial alications are rarely used

    a/o#e FF ;C.

    &o* sensiti#ity ?t can /e affected /y contact resistance , shock

    and #i/ration.

    Re1uires no oint sensin$. i$her cost than other temerature

    transducers.

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    "lications

     t is widely used in furnaces for automatictemperature measurement.

     ue to its compactness, it replaces conventional

    thermometers as well as thermocouples thuseliminatin# the use of lots of wires.

    sed in medical and chemical laboratories todetect very low temperatures like dry ice andli"uid nitro#en6

     ue to electrical output it is used whereverfeedback system is re"uired and correctiveaction is thus taken in an automated system.

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    Research Paers 'n RT(

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    'lick icon to add picture

     Corrosion Protection 'tions for Temerature Sensors

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    THAN- .O"

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    AN. &"ESTIONS 0

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