ILX Lightwave LDT-5525 User Manual page 48

Error T (°C)
1
R T Third Order Fit Eq 1
Actual
32128 0.00
19549 10.00
12262 20.00
9814 25.00
7908 30.00
5331 40.00
3542 50.00
For the LDT-5525, the Steinhart-Hart equation has been simplified to a first order polynomial:
1/T = A' + B' * ln R
This equation is easier to solve and provides adequate results. Table A.1 also shows that the use of Equation 2
introduces temperature errors of less than 0.3°C over the range -20 C to 50°C, with accuracies of up to 0.06°C over
smaller temperature ranges near room temperature
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1
Resistance of a 10 kΩ, Dale 1T1002-5 thermistor
Constants A' = 0.99 * 10 -3 , B' = 2.57 * 10 -4 (C1 = 0.99,
2
C2 = 2.57).
CURVE-FITTING EQUATION COMAPARISON
Error T (°C)
First Order Fit Eq 2
-0.0000
0.0005
-0.0001
-0.0002
0.0009
0.0003
-0.0030
Table A.1 Comparison of Curve Fitting Equations
Equation 2
2
.
-0.23
-0.11
-0.06
-0.06
-0.07
-0.15
-0.30
A-2