A Pt100 transmitter shows 200 deg C. What is the approximate resistance?
A. 165.8 Ω
B. 185.8 Ω
C. 175.8 Ω
D. 195.8 Ω
View Answer
Answer: C
Explanation:
A Pt100 RTD has a resistance of 100 Ω at 0°C. As temperature increases, its resistance increases according to the IEC 60751 standard.
Using standard Pt100 resistance tables:
- 100°C ≈ 138.5 Ω
- 150°C ≈ 157.3 Ω
- 200°C ≈ 175.9 Ω
Therefore, at 200°C, the resistance is approximately 175.8 Ω to 175.9 Ω.
For an approximate calculation:
Where:
- R₀ = 100 Ω
- α = 0.00385 /°C
- T = 200°C
The calculated value is close to the standard table value of 175.9 Ω.
Therefore, the correct answer is:
C. 175.8 Ω