23 Analog input module XN-322-10AI-TEKT
23.2 Wiring
170
XN300 slice modules
06/16 MN050002 EN
www.eaton.com
If the thermocouples are wired directly to the module, it is advisable to wire
the KTY sensor directly to the module as well. This will ensure that the tem-
perature measured has a value that depends on the module's outside and
inside temperatures and reflects the temperature at the thermocouple con-
nector's pin. In fact, the conditions at the pin will be comparable, provided
there are no localized temperature differences (X5 vs. X1). If this type of tem-
perature difference exists, as is the case when a system has specific sides
warm up in a localized manner during operation, it will affect the measure-
ment in the form of an error.
In order to isolate the measurement from the system assembly's local condi-
tions, as well as to compensate for large distances, it is possible to use
wheatstone bridge compensation circuits in which the thermocouples are
wired in a thermally stable environment, as is the measurement of the cold
junction temperature with the KTY sensor.
Figure 92:
Wiring example with 8 thermocouples and 2 KTY sensors; the
ϑ
M
measuring
points and the
ϑ
Ref1
and
ϑ
Ref2
reference junctions are clearly shown
X1
1+ 1- 2+ 2-
4-
X2
3+ 3- 4+
X3
X4
X5
K+ K- K+ K-
PE
24 V
0 V
8-
7+ 7- 8+
6-
5+ 5- 6+
ϑ
Ref1
ϑ
Ref1
ϑ
Ref2
ϑ
Ref2
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
+
-
ϑ
M
Summary of Contents for XN300
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