User manual

Publication 1747-UM011F-EN-P - May 2007
66 System Installation Recommendations
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
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.
SLC Logic Ground
SLC 500 Chassis
Processor
1746-P3
Door
A jumper wire is recommended
between the DC NEUT and Chassis
Ground of the external power source.
Earth Ground
Not Used
DH-485
Port
Earth Ground
External dc Power Source
+24 VDC
DC NEUT
Chassis
Ground
Not Used
+24V dc
DC Neut
Chassis
Ground
Safety Ground