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 +/-0.1% +/- 10V.

Slope dependiing of temperature :

Temperature ( C)

-200

-100

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 500C range, centered on 0C (non zero offset) with a PT100 probe.

Pt = Pl + Pz + Pm + Pd

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Escort 3008B, 3016B, 3004B user manual Accuracy of the PT100 measurements, Temperature C, Slope V/ C