6. How do I know what type of alpha (TCR) curve to use?

TCR (Temperature coefficient of Resistance) is the normalized average change in resistance of a sensing element over a specific temperature range (typically 0 to 100C).  The value is independent of the base resistance and is a characteristic of the element material itself. The units are measured in ohms/ohm/C.

Example: A probe may read 100 ohms at 0°C, but at 100°C, the .00385 probe will read 138.5 ohms and the .00392 probe will read 139.20 ohms. 

A. Resistance curve depends on instrumentation. Refer to your instrumentation manual for acceptable RTD (Resistance Temperature Detector) input types.

B. Common TCRs include:

Material
Temperature Coefficient
Platinum 0.00385 (EN 60751, IEC 751, DIN 43760, et al)
0.00391 (U.S. industrial standard)
0.00392 (highest purity platinum)
Copper 0.00427
Nickel-Iron
0.00518
0.00527 0.00518
0.00527

C. See our Resistance Thermometry white paper for detailed analysis.

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