Rockwell Automation 1771-IR , D17716.5.76 RTD INPUT MODULE - Manual (Page 61)

2 and 4-Wire Sensors
Appendix E
EĆ2
Figure E.2
Connections for 3 and 4-Wire Sensors
C
B
A
3-Wire Sensor
C
B
A
Leave Open
4-Wire Sensor
There are several ways to insure that the lead resistance values match as closely
as possible. They are:
use heavy gauge wire (16–18 gauge)
keep lead distances less than 1000 feet
use quality cable that has a small tolerance impedance rating.
Figure E.3 shows how to connect 4–wire sensors to the field wiring arm of the
RTD Input module. A 4–wire sensor has two pairs of leads; one pair for each
resistor junction. One wire of the 4 is not used (it does not matter which one).
This leaves 3 wires – one pair and one single wire. You must connect the single
wire to the terminal marked ”A”. You connect the remaining pair of wires to
terminals ”B” and ”C”. It doesn’t matter which wire of the pair connects to
terminal ”B” and which wire connects to terminal ”C” so long as all 3 wires are
the same AWG gauge.
Connecting 4-Wire Sensors