A Pt100 RTD generates approximately 109.7 Ω. What is the temperature?
A. 25°C
B. 35°C
C. 50°C
D. 65°C
View Answer
Answer: A
Explanation:
For approximate Pt100 calculations, use:
Where:
- R = Measured resistance = 109.7 Ω
- R₀ = 100 Ω
- α = 0.00385 /°C
Substituting the values:
109.7 = 100(1 + 0.00385T)
1.097 = 1 + 0.00385T
0.097 = 0.00385T
T ≈ 25.2°C
Verification
Typical Pt100 resistance values:
- 0°C → 100.0 Ω
- 25°C → 109.73 Ω
- 50°C → 119.4 Ω
- 100°C → 138.5 Ω
Since 109.7 Ω closely matches the standard Pt100 resistance at 25°C, the correct answer is:
A. 25°C