36 Rockwell Automation Publication MOTION-AT007A-EN-P - May 2020
Chapter 3 Non-regenerative Common DC-bus Configurations With Passive or Active Shunt
System Sizing
These limitations apply to systems supplied by a single 2198-Pxxx or multiple 2198-P208 DC-bus power supplies:
• The sum of the inverter motor-power cable lengths for all inverters on the same DC bus-sharing group must not exceed 1200 m
(3937 ft) to comply with IEC 61800-3 (category C3) requirements when used with 2198-DBRxx-F line filters. 2198-DBxx-F line filters have
a total motor cable length limit of 400 m (1312 ft). See the Kinetix 5700 Servo Drives User Manual, publication 2198-UM002
, for
additional motor power cable-length limitations.
• The total system capacitance limit is based on the power supply catalog number. DC-bus groups must not exceed the limits as
defined in Kinetix and PowerFlex Drive Specifications
on page 59.
• No more than three 2198-P208 DC-bus power supplies can be used to increase the converter power.
• If using the 24V DC shared-bus connection system, add another 24V power supply when control input power to a cluster of drive
modules exceeds 40 A.
• The Kinetix 5700 system can have multiple drive clusters in a single DC-bus group. See the Kinetix 5700 Servo Drives User Manual,
publication 2198-UM002
, for more information on extended clusters.
Refer to the Kinetix 5700 Servo Drives User Manual, publication 2198-UM002
, for additional information on system sizing guidelines.
The motor required for a particular application determines the drive required for full motor performance. For best results, use Motion
Analyzer system sizing and selection tool, available at https://motionanalyzer.rockwellautomation.com/
.
Capacitance Sizing
Total system capacitance is the sum of all internal capacitance values from each of the drive modules (AC drives, single-axis inverters, dual-
axis inverters, power supplies, and capacitor modules) in the same DC-bus group.
The total system capacitance must be less than the maximum supported DC-bus capacitance value of the power supply (refer to Kinetix and
PowerFlex Drive Specifications on page 59).
All drives have a DC-bus capacitance that is proportional to their power ratings. When used in a common DC-bus configuration, these
capacitors are directly connected in parallel. This connection results in the DC-bus ripple being shared proportional to the power rating of
the drive. When the ratio of the capacitance to the drive-rated current is consistent, it provides the best DC-bus ripple sharing.
For 400/480V AC, the target ratio is 40 µF/A ±10% or greater. For all drives supported in this publication, the target ratio is met when a
capacitor module is used to extend the DC-bus, proper DC-bus cable length guidelines are followed, and low-inductance DC cable is used.
See DC-bus Connections
on page 8 for more information.
Circuit Protection
Do not daisy chain drives to share DC-bus fusing. Configure the shared DC-bus in a star configuration to enable proper fusing. Use fast
semiconductor fuses in the DC links to minimize destructive energy in the event of a part or control malfunction. Size fuses to handle large
peak currents at the end of precharge.
•See Kinetix and PowerFlex Drive Specifications
on page 59 for the recommended common DC-bus circuit protection devices.
• See the Kinetix 5700 Servo Drives User Manual, publication 2198-UM002
, for recommended AC input circuit protection for the Bulletin
2198 power supply.
IMPORTANT If your total system capacitance value exceeds the maximum supported capacitance value of the DC-bus power supply, perform
one of the following:
• Increase the size of the 2198-Pxxx DC-bus power supply
• Use multiple 2198-P208 DC-bus power supplies (1…3 power supplies are possible with only 2198-P208 power supply)
• Decrease the total system capacitance by removing inverters or capacitor modules from the DC-bus group
• Separate clusters into multiple DC-bus groups
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