Rockwell Automation Publication DRIVES-AT005D-EN-P - May 2022 115
Appendix D
Mixed Architecture Resources
This appendix provides information about mixing various drive product lines and frame sizes that may be combined on a common DC bus system.
There are applications where some products can’t be used on the same common DC bus and others where external measures can be used to allow
mixing frames sizes and different drive architectures.
PowerFlex 750-Series 600V AC Mixed Architectures
To protect certain power components from damage, PowerFlex 750-Series frame 3…5 600v class AC drives (inverters) have a lower DC bus
overvoltage trip threshold than larger frame, dual-rated 600/690v class PowerFlex 750-Series AC drives.
For many applications, it’s necessary to apply PowerFlex 750-Series frame 3…5 inverters on the same common DC bus system with other larger
frame 600/690v PowerFlex inverters. When applying 600v class frame 3…5 inverters with other larger frame PowerFlex 750-Series and PowerFlex
755TM common bus inverters (CBI) on the same common DC bus system, you need to implement measures to make sure that the DC bus voltage
does not exceed the frame 3…5 DC bus overvoltage trip threshold during routine operation of the equipment.
This table shows the DC bus trip thresholds for various 600/690v Class PowerFlex inverters that could be used on the same common DC bus
system.
DC Bus Voltage Control Methods
A DC bus voltage control method is recommended, along with coordinated shutdown of larger frame PowerFlex inverters in the event of a DC bus
overvoltage fault on any of the frame 3…5 inverters. The regenerative device must be configured to clamp the DC bus voltage during normal routine
operation of the equipment to less than the lowest DC bus overvoltage trip level, in this case the 600V AC PowerFlex 750-Series frame 3…5
inverters.
The PowerFlex 755TM regenerative bus supply is a suitable method for controlling the DC bus voltage when implementing 600v PowerFlex 750-
Series frame 3…5 inverters on the same common DC bus system with other larger frame PowerFlex inverters. See Chapter 2
for information on
using the PowerFlex 755TM Regenerative Bus Supply.
When using a PowerFlex 755TM Non-regenerative Supply there are several external regenerative solutions for controlling DC bus voltage and
helping prevent nuisance DC bus overvoltage tripping, and possible damage to the 600V inverters:
• Common brake chopper and DB resistor. Third-party device, contact manufacturer for application information.
• Regen unit. Third-party device, contact manufacturer for application information.
IMPORTANT PowerFlex 750-Series 600v Class Frame 3…5 drives can’t be used with
690v AC power sources.
Voltage Class Supported Common DC Bus Inverters DC Bus Overvoltage Trip Voltage
600/690v
600v PowerFlex 750-Series; frame 3…5 1013V DC
600/690v PowerFlex 750-Series; frame 6…7 1162V DC
600/690v PowerFlex 755TM CBI; frames 8…15 1172V DC
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