Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 279)

Section 5A
9/440 Resolver--based CNC/Drive System
5A-33
Grounded vs Ungrounded Three Phase
The 9/440 Resolver--based CNC/Drive comes from the factory set for three
phase grounded systems. If your facility uses an ungrounded three phase
360/480 volt system, you must move a jumper in the 9/440 Resolver--based
system module. This jumper will connect an internal resistor that helps
keep high voltage static, that can be typical of ungrounded three phase
systems, from building up in the system module.
Jumper Setting Three Phase Power
J27 to J26 (factory setting) Grounded system
J27 to GND3 Ungrounded systems
Figure 5A.17
Three- phase Jumper
9/440 Resolver--based
System Module
Open cover
J2
6
J2
7
G
N
D
3
Wire Jumper