Allen-Bradley CompactBlock LDX 1790D-4T0, User Manual

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Publication 1790-UM003A-EN-P - May 2002
Installation and Wiring 2-13
Grounding
•
This product is intended to be mounted to a well-grounded
mounting surface such as a metal panel. Additional grounding
connections from the module’s mounting tabs or DIN rail (if used)
are not required unless the mounting surface cannot be grounded.
•
Keep cable shield connections to ground as short as possible.
•
Ground the shield drain wire at one end only. The typical location
is as follows.
– For grounded thermocouples or millivolt sensors, this is at the
sensor end.
– For insulated/ungrounded thermocouples, this is at the
module end. Contact your sensor manufacturer for additional
details.
•
If it is necessary to connect the shield drain wire at the module
end, connect it to earth ground using a panel or DIN rail mounting
screw.
•
Refer to Industrial Automation Wiring and Grounding Guidelines ,
Allen-Bradley publication 1770-4.1, for additional information.
Noise Prevention
•
To limit the pickup of electrical noise, keep thermocouple and
millivolt signal wires as far as possible from power and load lines.
•
If noise persists for a device, try grounding the opposite end of
the cable shield. (You can only ground one end at a time.)
ATTENTION
!
The possibility exists that a grounded or exposed
thermocouple can become shorted to a potential
greater than that of the thermocouple itself. Due to
possible shock hazard, take care when wiring
grounded or exposed thermocouples. See Appendix
D, Using Thermocouple Junctions.
AB Drives