Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 331)

Section 5B
9/440HR CNC/Drive System
5B-41
System Grounding
Figure 5B.23 illustrates the recommended 9/440HR grounding scheme.
All grounds terminate on a single point. Note there are two separate
ground wires going to the system module. One ground connects to PE of
the system module power terminal block, the other connects to the ground
stud found just beneath the wiring board on the mounting bracket for the
9/440HR CNC assembly.
9/440HR System Module
Open cover
9/440HR CNC
Assembly
PE Stud
Power Terminal Block
DC+ INT
COL W1
W2
U
W
V PE
PE Power Terminal Block Ground