Rockwell Automation 8720MC High Performance Drives Installation Manual - Manual (Page 22)

Publication 8720MC-IN001D-EN-P — December 2002
1-10 Installing Your 8720MC Drive
Fuse Selection
This section describes the fuse requirements for your 8720MC system.
The 8720MC utilizes internal short circuit output protection and is
suitable for use on a circuit capable of delivering up to 100,000
amperes, when protected by class CC, J, L, and R fuses. Circuit
breakers with adequate widthstand and interrupt ratings, as defined in
NEC 2002, article 110.9 and 110.10, are also allowed. Overcurrent
protection must be adequately coordinated per NEC 2002, article 240.
The 8720MC is listed by Underwriters Laboratories, Inc. with fuses
sized (FLA), according to UL 508C. Refer to Fuse Specifications in
Appendix A for recommended fuses.
In most cases, fuses selected to match the drive input current rating
will meet the NEC requirements and provide the full drive capabilities.
Dual element, time delay (slow acting) fuses should be used to avoid
nuisance trips during the inrush current of power initialization. Refer
to Power Specifications in Appendix A for input current specifications
for your 8720MC.
AC Input Fusing (380-460V ac)
The 8720MC AC input drives (8720MC-B021, -B027, -B034, -B042, and
-B048) are suitable for use in circuits that can deliver up to a
maximum of 70 rms amperes when used with the AC input line fuses
specified in Appendix A.
The 8720MC AC input drives do not contain input power short circuit
fusing. For the recommended size and type specifications for fuses
necessary to protect against short circuits, refer to AC Input Line Fuse
Ratings (380 to 460V ac Input) on page A-3.
Blower Motor Fusing
Protect all 8720SM motor fans with the use of 1A, time delayed,
current limiting fuses. Bussmann™ fuse (LP-CC-1) is recommended.
Refer to Appendix B for the 8720MC drive interconnect diagrams.