Rockwell Automation 1746-NT4 Series B,D17466.6.1 SLC 500 4-Channel Thermocouple/mV Input Module User Manual - Manual (Page 38)

Publication 1746-UM007C-EN-P - July 2004
3-10 Installation and Wiring
•
If it is necessary to connect the shield at the module, each input
channel has a convenient shield connection screw terminal that
provides a connection to chassis ground. All shields are
internally connected, so any shield terminal can be used with
channels 0-3. For maximum noise reduction, one shield terminal
must be connected to earth ground potential, i.e. mounting bolt
on 1746 chassis.
•
Tighten terminal screws using a flat or cross-head screwdriver.
Each screw should be turned tight enough to immobilize the
wire’s end. Excessive tightening can strip the terminal screw.
The torque applied to each screw should not exceed 5 lb-in
(0.565 Nm) for each terminal.
•
The open thermocouple detection circuit injects approximately
12 nanoamperes into the thermocouple cable. A total lead
resistance of 25 ohms (12.5 one-way) will produce 0.3 mV of
error. To reduce error, use large gage wire with less resistance
for long wire runs.
•
Follow system grounding and wiring guidelines found in your
SLC 500 Modular Hardware Style User Manual (publication
1747-UM011).