Escort 3016B - Manual (Page 135)

17 Appendix
Page 6
17.2. Accuracy of the thermocouple 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
Ps: cold weld accuracy
Pm: accuracy of the measurement of the equivalent voltage
Pd: accuracy of the measurement offsets
The total accuracy is then: Pt = Pl + Ps + Pm + Pd
For the recorder:
Pl = 0.25 C for all the thermocouples
Ps = 1.25 C for all the thermocouples
Pd = 0.15 % 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 of the thermocouple. For each thermocouple, an illustrative value of the slope is given at a
given temperature. This slope value is relevant for the thermocouple and allows you to calculate the
temperature error. If you want to have even further accuracy, you have to read the slope in the
thermocouple reference tables (because it changes with the temperature).
EXAMPLE OF ACCURACY CALCULATION
A measurement is made with the range 50 C centred on 25 C with a J thermocouple without cold
weld compensation.
Pt = Pl + Ps + Pm + Pd
Pl = 0.25 C (accuracy of standardisation)
Ps = 0 C (no cold weld compensation)
Pd = 0.04 C (+ 0.15 % of the temperature, paper medium)
Pm = 0.20 C (extracted from the table at range 50 C)
Max. total accuracy:
Pt = 0.25 + 0.04 +0.20 = 0.49 C