Rockwell Automation 1440-TB-E XM-944 Process/Temperature Terminal Base - Manual (Page 8)

8 XM-944 Process/Temperature Terminal Base
Publication GMSI10-IN024A-EN-P - May 2010
Wiring Requirements
Use solid or stranded wire. All XM wiring should meet the following
specifications:
• 14 to 22 AWG copper conductors without pretreatment; 8 AWG
required for grounding the DIN rail for electromagnetic interference
(emi) purposes
• Recommended strip length 8 millimeters (0.31 inches)
• Minimum insulation rating of 300V
• Soldering the conductor is forbidden
• Wire ferrules can be used with stranded conductors; copper ferrules
recommended
RTD Wiring Considerations
When using RTDs as inputs, give special consideration when selecting the
input cable. Select a cable that has consistent impedance throughout its entire
length.
When using a 3-wire configuration, the XM-361 compensates for resistance
error due to lead wire length. For example, in a 3-wire configuration, the
XM-361 reads the resistance due to the length of the wires and assumes that
the resistance of the other wire is equal. If the resistance of the individual lead
ATTENTION
See the XM Documentation and Configuration Utility CD for Hazardous
Locations installation drawings. The XM Documentation and Configuration
Utility CD is packaged with the XM modules.
IMPORTANT
The XM-361 requires three wires to compensate for lead resistance error.
We recommend that you do not use 2-wire RTDs if long cable runs are
required, as it reduces the accuracy of the system. However, if a 2-wire
configuration is required, reduce the effect of the lead wire resistance by
using a lower-gauge wire for the cable (for example, use 16 AWG instead of
24 AWG).