What does the temperature coefficient alpha describe for Pt100 RTDs?

What does the temperature coefficient alpha describe for Pt100 RTDs?

• A. It quantifies the resistance change per degree Celsius.
• B. It measures the maximum temperature.
• C. It indicates voltage output at 0°C.
• D. It defines the mechanical strength.

Answer: (A)

Alpha is the temperature coefficient of resistance for a Pt100 RTD, describing how much the resistance changes as temperature changes. For platinum RTDs, the resistance varies roughly linearly with temperature, and alpha is defined as (1/R0)(dR/dT) at 0°C. In a standard Pt100, R0 is 100 Ω at 0°C, and a common value for alpha is about 0.00385 per degree Celsius. This means the resistance changes by roughly 0.385 Ω per degree Celsius at the zero-temperature reference. For example, at 100°C, the resistance is about 100 × [1 + 0.00385 × 100] ≈ 138.5 Ω (ignoring higher-order terms). This is exactly what is meant by the resistance change per degree Celsius. The other options describe maximum temperature, voltage output at 0°C, or mechanical strength, which are not what alpha represents.

Alpha is the temperature coefficient of resistance for a Pt100 RTD, describing how much the resistance changes as temperature changes. For platinum RTDs, the resistance varies roughly linearly with temperature, and alpha is defined as (1/R0)(dR/dT) at 0°C. In a standard Pt100, R0 is 100 Ω at 0°C, and a common value for alpha is about 0.00385 per degree Celsius. This means the resistance changes by roughly 0.385 Ω per degree Celsius at the zero-temperature reference. For example, at 100°C, the resistance is about 100 × [1 + 0.00385 × 100] ≈ 138.5 Ω (ignoring higher-order terms). This is exactly what is meant by the resistance change per degree Celsius. The other options describe maximum temperature, voltage output at 0°C, or mechanical strength, which are not what alpha represents.