Installation Instructions User Manual

12 SLC™ 500 4-Channel Thermocouple/mV Input Module
Publication 1746-IN010D-EN-P - June 2004
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. (Also called Insulated Junction.)
• Exposed Junction - Does not have a protective metal sheath so the
measuring junction is exposed.
The illustration that follows shows each of the three thermocouple types.
Extension Wire
Metal Sheath
Measuring Junction is connected to sheath.
Measuring Junction is isolated from sheath.
Measuring Junction has no sheath.
Grounded Junction
Ungrounded (Insulated)
Junction
Exposed Junction