8/17/2019 Rtd Presentatn
1/16
RESISTANCE
THERMOMETER
By: Shashank
Pathak
EN – 4th Year
1
8/17/2019 Rtd Presentatn
2/16
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
2
8/17/2019 Rtd Presentatn
3/16
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.
3
https://en.wikipedia.org/wiki/Sensorhttps://en.wikipedia.org/wiki/Sensor
8/17/2019 Rtd Presentatn
4/16
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
4
8/17/2019 Rtd Presentatn
5/16
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
5
8/17/2019 Rtd Presentatn
6/16
Characteristics Of Materials "sed #or
RTD
Graph ofresistance vstemperatureof materials
like nickel ,copper &platinum hasbeen shown &
linearityproperty hasbeenobserved.
8/17/2019 Rtd Presentatn
7/16
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.
)
8/17/2019 Rtd Presentatn
8/16
0athematically it can /e *ritten as,
R56 R5 -27ₒ
*+5 8ith 52959538here, R56 "ro!imate resistance at 5;c
8/17/2019 Rtd Presentatn
9/16
&"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
0
8/17/2019 Rtd Presentatn
10/16
Ad*anta+es
&inearity o#er a *ide oeratin$ ran$e.
i$h accuracy
&o* drift
8ide oeratin$ ran$e
Suita/ility for recision alications.
1
8/17/2019 Rtd Presentatn
11/16
,imitations
RT(s in industrial alications are rarely used
a/o#e FF ;C.
&o* sensiti#ity ?t can /e affected /y contact resistance , shock
and #i/ration.
Re1uires no oint sensin$. i$her cost than other temerature
transducers.
11
8/17/2019 Rtd Presentatn
12/16
"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.
12
8/17/2019 Rtd Presentatn
13/16
Research Paers 'n RT(
13
8/17/2019 Rtd Presentatn
14/16
'lick icon to add picture
Corrosion Protection 'tions for Temerature Sensors
14
8/17/2019 Rtd Presentatn
15/16
THAN- .O"
15
8/17/2019 Rtd Presentatn
16/16
AN. &"ESTIONS 0
1
Top Related