Keithley 2700 - Page 452

Model 2700 Multimeter/Switch System User’s Manual Temperature Equations F-9
RTD parameters for equations
The RTD parameters for the Callendar-Van Dusen equations are listed in Table F-10.
Example 1
Calculate the resistance of a PT100 RTD at 100°C (T). The following R
0
(Ω at 0°C), alpha,
and delta values are used for the PT100 RTD (
Table F-10):
T = 100°C
R
0
(Ω at 0°C) = 100Ω
alpha = 0.003850
delta = 1.49990
Using the above alpha and delta values, A and B are calculated as follows:
A = 0.00385 [1 + (1.4999/100)]
= 0.00385 (1.014999)
= 0.003907746
B = -1 (0.00385)(1.4999)(1e-4)
= -1 (0.005774615)(1e-4)
= -5.774615e-7
The resistance of the RTD at 100°C (R
100
) is then calculated as follows:
R
100
= R
0
[1 + AT + BT
2
]
= 100 {1 + [(0.003907746)(100)] + [(-5.774615e-7)(100
2
)]}
= 100 [1 + 0.3907746 + (-0.005774615)]
= 100 (1.385)
= 138.5Ω
Table F-10
RTD parameters
Type Standard Alpha Beta Delta Ω at 0°C
PT100 ITS-90 0.003850 0.10863 1.49990 100Ω
D100 ITS-90 0.003920 0.10630 1.49710 100Ω
F100 ITS-90 0.003900 0.11000 1.49589 100Ω
PT385 IPTS-68 0.003850 0.11100 1.50700 100Ω
PT3916 IPTS-68 0.003916 0.11600 1.50594 100Ω