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EX10xxA Triggering
69
U
SER
-
DEFINED
C
ONVERSIONS
The EX10xxA nominally accepts standard thermocouple types and performs its thermocouple
calculations using polynomial coefficients from the NIST ITS-90 Thermocouple Database. In some
applications, however, a user may want to override the embedded coefficients with a user-defined
coefficient set. One reason to do this is if the transfer function of the specific thermocouple being
used has been completely characterized to an accuracy level that exceeds standard thermocouple
limits of error. Another reason to do this is if a non-standard thermocouple is used. Up to two unique
sets of coefficients can be entered. Specifically, the use of custom thermocouple equations requires
the user to know or generate the coefficients for two conversion polynomials.
The
forward conversion polynomial
is used to convert a CJC temperature into a compensating cold
junction voltage and has the form of:
12
12
2
2
1
1
0
*
*
*
t
c
t
c
t
c
c
E
where
E
is in volts,
t
is in ºC, and
c
0
- c
12
are the coefficients.
The
inverse conversion polynomial
is used to convert a compensated input voltage into temperature
and has the form of:
12
12
2
2
1
1
0
*
*
*
E
d
E
d
E
d
d
t
where
E
is in volts,
t
is in ºC, and
d
0
- d
12
are the coefficients.
The default values for the coefficients are 0.0.
NOTE
The entry of user-defined coefficients does not automatically enable their use. The enabling is done
by setting the EU conversion to User0 or User1.
Содержание EX1000A
Страница 25: ...www vtiinstruments com EX10xxA Introduction 25 FIGURE 1 2 RACKMOUNT HARDWARE INSTALLATION DIAGRAM ...
Страница 27: ...www vtiinstruments com EX10xxA Introduction 27 FIGURE 1 4 ISOMETRIC AND INTERNAL CJC PLATE DIAGRAM ...
Страница 28: ...VTI Instruments Corp 28 EX10xxA Introduction EX1044 DIAGRAM ...
Страница 29: ...www vtiinstruments com EX10xxA Introduction 29 FIGURE 1 5 EX1044 TABLE TOP USAGE ...
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