14
SLC 500 Thermocouple/mV Analog Input Module
Publication 1746-5.23
Wiring Guidelines
Isolation
7KH17PRGXOHSURYLGHVWKHIROORZLQJHOHFWULFDOLVRODWLRQ
• 12.5V dc electrical isolation channel to channel
• 500V dc electrical isolation channel to chassis ground
• 500V dc electrical isolation channel to backplane
Care must be taken when choosing a thermocouple type and connecting it to the
1746-NT8 module from the environment being measured. If adequate
precautions are not taken for a given thermocouple type, the electrical isolation
of the 1746-NT8 module may be compromised.
Thermocouple Junctions
There are three types of thermocouple junctions:
• Grounded Junction - The measuring junction is physically connected to the
protective metal sheath providing electrical continuity between junction and
sheath.
• Ungrounded Junction - The measuring junction is electrically isolated from
the protective metal sheath. (Ungrounded Junction can also be called
Insulated Junction.)
• Exposed Junction - Does not have a protective metal sheath so the
measuring junction is exposed.
Note:
Please refer to Appendix A of the SLC 500 Thermocouple/mV
Analog Input User Manual, publication 1746-6.22 for additional
information on wiring and using grounded junction, ungrounded
junction, and exposed junction thermocouple types.
