Filter
Top Products
ROC827 Instruction Manual
Issued Mar-06 Input/Output Modules 4-18
J OR K THERMOCOUPLE
UNGROUNDED SHEATH
+
-
DOC0512B
Figure 4-15. Type J and K Thermocouple Wiring
Be sure to use the correct type of thermocouple wire to connect the
thermocouple to the ROC827. Minimize connections and make sure
connections are tight. If you use any dissimilar metals (such as copper
wire) to connect a thermocouple to the ROC827, you can create the
junction of dissimilar metals that can generate millivolt signals and
increase reading errors.
Ensure any plugs, sockets, or terminal blocks used to connect the
extension wire are made from the same metals as the thermocouples and
observe correct polarity.
The thermocouple probe must have sufficient length to minimize the effect
of conduction of heat from the hot end of the thermocouple. Unless there
is insufficient immersion, readings will be low. It is suggested the
thermocouple be immersed for a minimum distance equivalent to four
times the outside diameter of a protection tube or well.
Use only ungrounded thermocouple constructions. Grounded
thermocouples are susceptible to the creation of ground loops. In turn,
ground loops can cause interaction between thermocouple channels on the
thermocouple module.
Note: Use thermocouples as individual sensing devices. All modules are
isolated on the field side. Be aware that you can induce ground loops by
tying module-to-module commons together.