Rockwell Automation 8720MC High Performance Drives Installation Manual - Manual (Page 23)

Publication 8720MC-IN001D-EN-P — December 2002
Installing Your 8720MC Drive 1-11
8720MC-RPS Fusing
The 8720MC DC input drives (8720MC-Bxxx and -Dxxx) are suitable
for use in circuits that can deliver up to a maximum of 250 rms
symmetrical motor amperes when used with the 8720MC-RPS and the
AC input line fuses specified in 600V ac Input Fuse Specifications on
page A-4.
When two or three 8720MC-RPS065 Regenerative Power Supplies are
operating in a master/slave mode, the output load is shared equally
between the power supplies. When a master and one slave is required
input fuses and wire should be sized to 1/2 of the total required
maximum continuous input current for the total required drive load,
multiplied by 1.75. When a master and two slaves are required input
fuses and wire should be sized to 1/3 of the total required maximum
continuous input current for the total required drive load, multiplied
by 1.75.
Refer to Appendix B for the 8720MC drive with 8720MC-RPS
interconnect diagrams. For more information on the 8720MC-RPS
Regenerative Power Supply, refer to the 8720MC Regenerative Power
Supply User Manual (publication 8720MC-RM001x-US-P).
DC Input Fusing (750V dc)
When multiple drives and/or master/slave RPS units are needed to
meet the load requirements a common bus architecture is preferred.
For common bus applications Allen-Bradley’s Bulletin 140 bus bar and
panel mounting components are recommended. Size the bus bar
capacity to at least 175% of total RPS continuous output current. The
DC input wire and fuses to each drive should be sized to 175% of
each drives’ maximum continuous input current requirements.
All fuses on the DC bus must be rated for 1,000V dc operation. For DC
bus fuses use Gould A1-100P, Gould A100C (80 amps and higher) or
equal. Refer to the 8720MC Regenerative Power Supply User Manual
(publication 8720MC-RM001x-US-P) for master/slave RPS
configurations.
When a single RPS is matched to a single drive, DC drive input fuses
are not required. The following table is used to select DC drive input
fuses and assumes more than one drive is connected to the RPS
common bus, otherwise DC drive input fuses are not required.
Suggested wire sizes assume single conductor connections. It is
perfectly acceptable to use 2 or 3 conductors in parallel as long as the
total amperage requirements are met. For example 2 parallel #12
conductors could be used in place of a single # 10 conductor.
Refer to 1000V dc Input Fuse Specifications on page A-5 and
Appendix B for interconnect diagrams.