
17 Appendix
17.3.Accuracy of the PT100 measurements
The measurement inaccuracies thereafter are given as maximum values: typical values are 2 to 3 times less.
The measurement accuracy in temperature is the sum of several possible sources of inaccuracy: Pl: accuracy of standardisation
Pz: zero accuracy
Pm: accuracy of the measurement of the equivalent voltage
Pd: accuracy of the measurement offsets
The total accuracy is then: Pt = Pl + Pz + Pm + Pd
For the recorder:
Pl = 0.25
C for the PT100
Pz = 0.25
C for the PT100
Pd = 0.10 % of the offset
Pm = given in the tables
Measurement accuracy: Pm
The measurement accuracy Pm depends on the voltage range used by the appliance. The measurement error in degrees will then be the measurement error in voltage divided by the slope in V/C.
For all the voltage ranges, the accuracy is V.
Slope dependiing of temperature :
Temperature ( C) | 0 | 200 | 400 | 600 | 800 | ||
Slope ( V/ C) | 378 | 354 | 342 | 321 | 301 | 281 | 260 |
Equivalent voltage measurement accuracy at 0C :
Temperature | Tension | Max error | Max Error |
Range | Range | ( V) | ( C) |
20 | 10 | 20 | 0.06 |
50 | 20 | 30 | 0.09 |
100 | 50 | 60 | 0.18 |
200 | 100 | 110 | 0.32 |
500 | 200 | 210 | 0.60 |
1000 | 500 | 510 | 1.50 |
2000 | 1000 | 1010 | 3.00 |
EXAMPLE OF ACCURACY CALCULATION
The measurement is about 240C made with the 500
C range, centered on 0
C (non zero offset) with a PT100 probe.
Pt = Pl + Pz + Pm + Pd
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