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 Question Submitted By :: Instrumentation
I also faced this Question!!     Answer Posted By  
# 1
Thermocouple when senses gives "mv" readings to the
transmitter. RTD gives "ohm" readings to the transmitter.
For checking put the multimeter in resistance mode and if
the the sensor is throcouple the meter will indicate
almost"0" resitance whereas the RTD would indicate
around "119 ohms" in normal temperature like 30deg.C
Is This Answer Correct ?    202 Yes 20 No
# 2
Thermocouple is basically couple of two dissimilar matel
wire which generate certain emf on puting the couple end in
higher temperature source.As emf is generated then it can
measure in terms of mV.Phisically we can check the T/c by
checking it two wires, they will be of different
material/metal alloy.

RTD is resistance temperature detector works on the basis
of resistance changes when temperature changes. Physically
they can be identified by wire exposed to make
connection.In normally everyone uses three wire RTD, in
which 2 wires are of same insulation colour and resistance
between them will be nearly 2-3 Ohms. The resistance b/w
third wire and any of those wire will be 119.5 Ohms at room
temperature.RTD never generate emf hence we can't measure
any mV b/w any of wire of RTD.
Is This Answer Correct ?    66 Yes 4 No
Yadav Manoj
# 3
rtd can be checked by measuring the resistance accross the
terminals. At room temp rtd has got a resistance around
110ohm when neasured across its terminal.
t/c can be checked by measuring mv at the terminals
connected. the corresponding mv is corelated with mv v/s
temperature chart to find the temp.
Is This Answer Correct ?    54 Yes 9 No
# 4
T/C : Just check the contunity
RTD : Check the ohms to the corresponding type of RTD tro
DIN Chart.

* Difference : RTD : Resistance Temperature Detector
The name itself specifies resistance varies according to
the temperature the element detects.

Thermocouple : Thermo : Thermal , Couple : Coupled.
The thermal difference between the coupled point and
seperated point of a thermocouple produces the MV.(Depends
upon the type of T/C)
Is This Answer Correct ?    49 Yes 5 No
# 5
at room temp resisstence of rtd is higher than thermocouple. 
Is This Answer Correct ?    59 Yes 23 No
Yogendra Kumar
# 6
Simply open the top cover of the device. If the connection
points has + & - symbol indication then it is THERMOCOUPLE,
otherwise it is RTD
Is This Answer Correct ?    38 Yes 9 No
Laxman Sonawane
# 7
more answers are here. Answer No 7 is currect.
but one thing is missed about the color coding of thermo
couple. mostly in industrial section we are using K, E, J,
T , types we can understand the these types from the color
code of TC. you will get further details on
Is This Answer Correct ?    8 Yes 2 No
# 8
t/c base of seeback & rtd base of wheatstone bridge kcl.rtd
linear & t/c some distane linear another non linear. t/c
extention cable same use & rtd any other wire use to have.
Is This Answer Correct ?    8 Yes 2 No
# 9
the output of thermocouple is mV so check the mV in diff
temperatures and the output of RTD is resistance so measure
the resistance at normal temp it should be greater or equal
to that ohm specific of RTD type .For Example if it is PT100
so it will shows minimum 100 ohm if RTD is in working condition.
Diff bet T/C and RTD
both are used to measure temperature but RTD is more
accurate than T/C
RTD can be used upto 800 deg but T/C can be used upto 1750 deg
Is This Answer Correct ?    4 Yes 0 No
Manish Parate
# 10
thermocouple is active devise and works on seeback effect
prociplal which is manufature by using two dissmillar metal
because of this diffrence in property of diffternt alloy
when join togeather at one end it will give milli volts
when u measure across other end of the terminal and it can
use for the measuring higher range temperatue till max 1300
degree centigarde
RTD is passive devise and positive temperature coefficent
its resistance increse as temperature increses and it made
up of platinum and works on wheatstone bridge principal and
its temprature measuring range is from -270 to max 700 and
acuracy is good and it will act variable arm of wheat stone
Is This Answer Correct ?    3 Yes 0 No
Mohammed Abbas

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