What Is RTD Temperature sensors RTD Classification based on wire & complexity Temperature Calculation

2. RTD Types:
•RTD Classification based on
Connections:
•Simplex RTD:
•Single goes to one location only.
•Has one sensor in the RTD so
efficiency is less.

3. RTD Types:
•RTD Classification based on
Connections:
• Duplex RTD:
• Single goes to 2 different locations
like PLC/DCS/SCADA & Indicator.
• Has 2 sensor in the RTD so
efficiency is high.

4. RTD Types:
•RTD Classification based on Wires:
• 2 Wired RTD.
• 3 Wired RTD.
• 4 Wired RTD.

5. RTD Types:
•RTD Classification based on Wires:
• 2 Wired RTD:
• Used For Short Distance approx.
2-3 meter after that singles
might be inaccurate.

6. RTD Types:
•RTD Classification based on Wires:
• 3 Wired RTD:
• Used For long Distance. 3rd wired
given for resistance compensation.
• High Accuracy compared to 2 wire
RTD.
• Commonly used in industries.

7. RTD Types:
•RTD Classification based on Wires:
• 4 Wired RTD:
• High Accuracy compared to 2 or
3 wire RTD.
• Used where high accuracy is
required.

8. Temperature From Resistance:
•Metal has a definite value of resistance at a particular temperature.
•The value of resistance changes with the change in its temperature
and is very predictable.
•So We can calculate the temperature of metals by knowing its
resistance.
•The resistance of an RTD at any temperature (RT) can be calculated
from the following formula:
Where, Ro = resistance of RTD at 0oC.
α = temperature coefficient of resistance
T = (RT /Ro - 1)/ α

9. Temperature From Resistance:
•For Example:
for RTD PT100, Ro = 100 ohms, α = 0.00385 ohms/oC & RT Showing in
multi-meter is 150 Ω Then What will be T:
T = (RT /Ro - 1)/ α
T = (150/100 - 1)/
0.00385
T = 129.8oC