20
Rockwell Automation Publication DRIVES-AT005D-EN-P - May 2022
Chapter 2 Regenerative Bus Supply Configuration
• The AC input power jumpers (PE-A) must be placed in the correct positions according to the power source grounding method. The PowerFlex
755T regenerative bus supply and all connected inverters must have the DC bus jumpers (PE-B) removed or set to 'out' regardless of the AC
power source grounding method. The Kinetix 5700 servo drives must have the ground screw/jumpers removed. The PowerFlex 755T
regenerative bus supply is an active converter.
For recommended settings and instructions for modifying the position of the power jumpers, see the following publications:
- PowerFlex 750-Series Products with TotalFORCE® Control installation instructions, publication
, or PowerFlex 755TM IP00 Open
Type Kits installation instructions, publication
.
- PowerFlex 750-Series AC Drive installation instructions, publication
750-IN001
.
- Kinetix 5700 Servo Drives user manual, publication
2198-UM002
.
Precharge Interlocking
For more information about DC bus precharging and inverter precharging circuit configurations, see
• If a disconnect switch is used between the common DC bus and the inverter DC input, the inverter must have precharging capability. In
addition, an auxiliary contact on the disconnect switch that opens when the disconnect is open must be wired to an inverter digital input. The
corresponding digital input must be assigned to the 'Precharge' enable function.
- PowerFlex 750-Series drives - assign to parameter 0:189
[DI Precharge]
. See PowerFlex 750-Series AC Drives programming manual,
publication 750-PM001, for more information.
- PowerFlex 755TM common bus inverters - assign to parameter 0:190
[DI Precharge]
. See the PowerFlex Drives with TotalFORCE Control
programming manual, publication
750-PM100
, for more information.
This configuration provides the proper precharge interlocking, which guards against possible damage to the drive when reconnecting the
drive to an energized DC bus.
• The precharge status of the PowerFlex 755TM regenerative bus supply should be interlocked with the connected drives, such that the drives
are disabled (not running) when the PowerFlex 755TM regenerative bus supply is in a precharge state. This can be accomplished by
monitoring bus supply line side converter parameter 13:225.25
[Line Side Sts 1]
. This status bit can be connected to the PowerFlex 'Enable'
and Kinetix 5700 'Regeneration OK' control via:
- hardwired bus supply I/O connection to inverter/drive local I/O
- Logix controller I/O
- communication DataLink within the Logix control program task.
Product may require optional I/O modules if hardwired interlocking methods are used.
AC Power System Resonance Conditions
PowerFlex 755TM regenerative bus supplies use active front end technology that is designed to reduce AC line harmonics introduced by the
product. When AC power is supplied by a dedicated isolation transformer, additional filtering devices are typically not required. When other non-
linear loads (such as 6-pulse diode and thyristor converters used by conventional AC drives) share AC supply sources with PowerFlex 755T active
front end products, there can be interaction between the various filters that can cause power system resonance. This condition causes component
stress, excess heating, and can result in reduced product life. Because the interaction of each load must be considered, system resonance
conditions are challenging to predict.
If other non-linear loads (6-pulse AC drives or active front end converters) share the same AC source, it may be necessary to install a 3-phase line
reactor between the PowerFlex 755TM regenerative bus supply and the AC power source. For detailed information about power system resonance
conditions and mitigation techniques, see Knowledgebase Technote
Power System Resonance Mitigation for PowerFlex 755TL/TR/TM
.
ATTENTION:
The DC bus power jumpers for PowerFlex 755T bus supply (PE-B), all
connected PowerFlex inverters (PE-B), and all Kinetix 5700 servo drives (ground
screw/jumper) must all be set to the same condition: all removed (out). Risk of
equipment damage exists if the DC bus power jumpers aren’t all set to the same
condition.
ATTENTION:
The Kinetix family of drives and some PowerFlex AC drives have no
external means of controlling the precharge; therefore, a DC disconnect switch
must not be used without the use of an external precharge device. See
for more information.