National Instruments Module SCXI-1503 User Manual page 39

© National Instruments Corporation
Table 4-1. Platinum RTD Types (Continued)
Temperature
Coefficient of
Standard (TCR, PPM)
US Industrial
Standard
American
ITS-90
1
No standard. Check TCR.
For temperatures above 0 C, coefficient C equals 0, reducing this equation
to a quadratic. If you pass a known current, I
measure the output voltage developed across the RTD, V
for T as follows:
T
= ----------------------------------------------------------------------------------------------- -
–0.5 R
where
V is the measured RTD voltage.
0
I is the excitation current.
EX
Resistance Typical
R
0
3911 100
3928 100
V
0
R
– ------ -
0
I
EX
⎛
2 2
⎜
A R A 4R
+ –
0 0
⎝
4-9
Chapter 4 Theory of Operation
Callendar-Van
Dusen Coefficient
A = 3.9692 10
B = –5.8495 10
C = –4.233 10
A = 3.9888 10
B = –5.915 10
–12
C = –3.85 10
, through the RTD and
EX
, you can solve
0
⎞
V
⎛ ⎞
0
⎟
B R
– ------ -
⎝ ⎠
0 0
I
⎠
EX
SCXI-1503 User Manual
–3
–7
–12
–3
–7