Rockwell Automation Publication DRIVES-AT005D-EN-P - May 2022 29
Chapter 3
Shared DC Bus Configuration (Piggyback)
This system features one standalone PowerFlex® 755TL or PowerFlex 755TR drive, as the converter and additional common DC bus drives are used
in a shared DC bus configuration.
Supported Products
At the time of publication, the following products are supported.
Typical System Configuration
This section describes typical configurations for the PowerFlex 755TL/TR drive used as a shared DC bus supply. The shared DC bus configuration
includes one AC drive powering one or more inverters shown in this chapter’s supported products table.
It’s recommended to use a dedicated isolation transformer that only supplies AC power to the PowerFlex 755TL/TR AC drive. If other non-linear
(diode/SCR rectifiers) or active front end (AFE) AC loads are connected to the secondary of the isolation transformer, additional line reactors may be
required. See AC Power System Resonance Conditions on page 32
for more information.
The PowerFlex 755TL/TR drive can be used with solid grounded, high-resistance grounded, and ungrounded AC power sources. Solid grounded and
resistance grounded power sources are recommended for typical grid powered AC sources to improve electrical safety, ease of ground fault
detection, and to reduce unbalanced voltages.
Ungrounded (floating ground) AC power sources are typically used for shipboard isolated power systems that aren’t earth grounded.
Resistance grounded and ungrounded (floating ground) power sources may require additional user supplied circuits and optional bus conditioners
(-P50 or -P51).
Bus Supply Products Voltage Class Supported Inverters Inverter DC Bus Overvoltage Trip
(1)
(1) DC bus voltage control methods may be required to limit the maximum routine system DC bus voltage to less than the lowest inverter DC bus overvoltage trip level. See Appendix D
for more information.
PowerFlex 755TL (20G…)
(2)
Frames 5…6
(3)
, Frames 8…10
(4)
or
PowerFlex 755TR (20G…)
(5)
Frames 5…6
(3)
, Frames 8…15
(4)
(2) PowerFlex 755TL input type (position 5 of catalog number) = 7 (frame 5…6 Low Harmonic AFE, 755TL Drives) or G (frame 8…10 Low Harmonic AFE, 755TL Drives). Frame 7 drive
shared DC bus configurations aren’t supported at this time.
(3) PowerFlex 755TL/TR frame 5…6 drives are panel-mounted devices that require additional external AC input power conditioning equipment. If frame 5…6 drives are used, see the
Installation Manual, publication 750-IN100
, for additional installation and external device information.
(4) PowerFlex 755TL/TR frame 8…15 AC drives require extension of the DC bus bars and other modifications. See DC Bus Termination on page 32 for more information.
(5) PowerFlex 755TR input type (position 5 of catalog number) = 6 (frame 5…6 Regenerative and Low Harmonic AFE, 755TR Drives) or F (frame 8…15 Regenerative and Low Harmonic
AFE, 755TR Drives). Frame 7 drive shared DC bus configurations aren’t supported at this time.
400/480V AC
400/480V AC PowerFlex 750-Series: frames 2…7
(6)(7)
(6) PowerFlex 750-Series input type (position 5 of catalog number) = 1 (frames 2…4 AC input with precharge, includes DC terminals) or, 4 (frames 5…7 DC input with precharge).
(7) At this time, frame 1 drives aren’t recommended for use with common DC bus systems.
815V DC
600/690V AC
600V AC PowerFlex 750-Series: frames 3…5
(6)(8)
(8) 600V AC frame 3…5 inverters can’t be used on 690V AC systems. See Appendix D for more information.
1013V DC
600/690V AC PowerFlex 750-Series: frames 6…7
(6)
1162V DC
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