Special Grounding Considerations For Dc Applications Using 1746-P3 (Previous To Revision B) - Allen-Bradley SLC 500 User Manual

System Installation Recommendations
64
External dc Power Source
+24 VDC
DC NEUT
Chassis
Ground
Earth Ground
Publication 1747-UM011G-EN-P - June 2008
Special Grounding Considerations for dc Applications using
1746-P3 (previous to revision B)
This information describes special wiring considerations for the 1746-P3
power supply that is not labeled as revision (REV) B or later-.
Keep wire length as short as possible.
ATTENTION
1746-P3
Door
Not Used
Not Used
+24V dc
DC Neut
Chassis
Ground
A jumper wire is recommended
between the DC NEUT and Chassis
Ground of the external power source.
Any voltage applied to the 1746-P3 DC NEUT terminal will be
present at the SLC logic ground and the processor DH-485 port.
To prevent unwanted potentials across the logic ground of the
controller and/or damage to the SLC chassis, the DC NEUTRAL
of the external dc power source must be either isolated from
the SLC chassis ground, or connected to earth ground.
Processor
DH-485
Port
SLC Logic Ground
Safety Ground
SLC 500 Chassis
Earth Ground