Allen-Bradley MicroLogix 1200, User Manual, Page: 125 / 144

Publication 1762-UM002A-EN-P - July 2002
Using Thermocouple Junctions D-3
Using an Exposed Junction
Thermocouple
An exposed junction thermocouple uses a measuring junction that
does not have a protective metal sheath. A thermocouple with this
junction type provides the fastest response time but leaves
thermocouple wires unprotected against corrosive or mechanical
damage.
As shown in the next illustration, using an exposed junction
thermocouple can result in removal of channel-to-channel isolation.
Isolation is removed if multiple exposed thermocouples are in direct
contact with electrically conductive process material.
Measuring Junction Isolated from Sheath
Measuring Junction with No Sheath
+
-
IN 0
+
-
IN 3
1762-IT4
Exposed Junction with Shielded Cable
Multiplexer
Conductive Material
AB Parts