Keithley 2700 - Page 453

F-10 Temperature Equations Model 2700 Multimeter/Switch System User’s Manual
Example 2
Calculate the resistance of a D100 RTD at -100°C (T). The following R
0
(Ω at 0°C), alpha,
beta, and delta values are used for the D100 RTD (
Table F-10):
T = -100°C
R
0
(Ω at 0°C) = 100Ω
alpha = 0.003920
beta = 0.10630
delta = 1.49710
Using the above alpha and delta values, A and B are calculated as follows:
A = 0.003920 [1 + (1.49710/100)]
= 0.003920 (1.014971)
= 0.003978686
B = -1 (0.003920)(1.49710)(1e-4)
= -1 (0.005868632)(1e-4)
= -5.868632e-7
C = -1 (0.003920)(0.10630)(1e-8)
= -1 (0.000416696)(1e-8)
= -4.16696e-12
The resistance of the RTD at -100°C (R
100
) is then calculated as follows:
R
100
= R
0
[1 + AT + BT
2
+ CT
3
(T-100)]
= 100 {1 + [(0.003978686)(-100)] + [(-5.868632e-7)(-100
2
)] +
[(-4.16696e-12)(-100
3
)](-100-100)}
= 100 [1 + (-0.3978686) + (-0.005868632) + (0.000833392)]
= 100 (0.5954294)
= 59.54294Ω