![background image](http://html1.mh-extra.com/html/omega/cl3001/cl3001_user-manual_737625027.webp)
To use a custom RTD curve:
a)
Select RTD measure or source mode as described in the
preceding sections.
b)
Press the
key until the USR_DEF type is selected.
c)
Press the
key to display the curve selection prompt
"RTD CUSTOM (1-5)".
d)
Press the numeric key corresponding to the custom RTD
curve to be used.
e)
At the "SET(1)/RECALL(2)" prompt, press
to recall the
custom RTD curve coefficients.
f)
To use a different custom RTD curve, press the
key
twice to display the USR_DEF selection prompt.
The USR_DEF function of the CL3001 uses the Calendar-Van Dusen
equation for sourcing and measuring custom RTD's. The C
coefficient is only used for the subrange -260 to 0 degrees Celsius.
Only the A and B coefficients are needed for the subrange 0 to 630
degrees. The R0 value is the resistance of the probe at 0 degrees
Celsius.
All 5 of the custom RTD curves are set to PT385 at the factory, as
shown in Table 2.
Table 2 - Default Custom RTD Coefficients
Curve
Subrange
R0
Coefficient A
Coefficient B
Coefficient C
1
0 to 630
100
3.9083e10-3
-5.775e10-7
0
2
-260 to 0
100
3.9083e10-3
-5.775e10-7
-4.183e10-12
3
0 to 630
100
3.9083e10-3
-5.775e10-7
0
4
-260 to 0
100
3.9083e10-3
-5.775e10-7
-4.183e10-12
5
0 to 630
100
3.9083e10-3
-5.775e10-7
0
Table 3 shows the coefficients for RTD types PT391 and PT392. The
C coefficient is only used for temperatures below 0 degrees Celsius.
Table 3 - Other Common RTD Coefficients
RTD Type
R0
Coefficient A
Coefficient B
Coefficient C
PT392
100
3.9848e10-3
-5.87e10-7
-4.0e10-12
PT391
100
3.9692e10-3
-5.8495e10-7
-4.2325e10-12
23
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