Rockwell Automation Publication DRIVES-AT005D-EN-P - May 2022 39
Chapter 4 Non-regenerative Bus Supply Configuration
General Considerations
• All system components must be selected for the same AC-line voltage.
• A low inductance type DC bus must be used. See DC Bus Connections on page 10
for details.
• A minimum DC bus capacitance greater than 110 uF is required to help ensure that the bus supply will power up if there is no other
connected DC bus capacitance. Typically, this only occurs during commissioning when all inverters may be disconnected from the DC bus.
The PowerFlex 755TM non-regenerative supply does not include any internal DC bus capacitance as standard. If required, confirm that the
minimum connected capacitance is provided by optional internal capacitor modules or an external capacitor module of at least 110 uF. See
Appendix B
for more information about external capacitor modules.
• The common DC bus system may require feeder and branch circuit protection and disconnect devices. Provide appropriate circuit
protection as required by national and local electrical safety codes and regulations.
• Depending on product family and frame size, AC and/or DC fuses may be provided internally or must be supplied external to the product by
the user. See Appendix A
and the product technical data manuals for recommended fuse information.
• PowerFlex 755T AC drives and bus supplies must not be used on undersized or high-impedance AC supply systems. The supply system kVA
must be equal to or greater than the product-related kVA, and the system impedance must be less than 10%. You must account for the kVA
of all PowerFlex 755T drives and bus supplies on the distribution system and the system impedance of upstream transformers.
- System Impedance = (PowerFlex 755T kVA ÷ Transformer kVA) x Transformer % Impedance
• The mixture of different frame size drives in this arrangement can cause high ripple current in the smaller frame drives. In this case, place
the larger power drives physically closer to the bus supply. This helps current sharing among the various drives on the bus.
Table 3 - Compatibility Table
System
Voltage
Bus Supply Inverter
Common Mode Core DC Bus ConditionerQty. Type Qty. Type
400/480V AC
1…6
(1)
(1) When paralleling Non-regenerative Supplies, derating factors are applied. See Paralleling PowerFlex 755TM Non-regenerative Modules on page 41 for more information.
PowerFlex 755TM
Non-regenerative
Supply
(2)
(20JEH...):
Single Density,
Dual Density
(2) See PowerFlex 755TM System DC Bus Ratings on page 99 for guidance on PowerFlex 755TM system DC bus selection.
n
(3)
(3) The number of inverters that can be connected may be limited by the precharge capability of the PowerFlex 755TM non-regenerative supply. See DC Bus Capacitance Calculation Method on page 87
for more information about DC bus capacitor calculations and system capacitance precharging requirements and the maximum external DC bus capacitance that can be connected.
400/480V AC PowerFlex 750-Series: frames 2…3
1321-M048
(4)
(4) For PowerFlex 750-Series frame 2…7 drives, cores are required on inverter AC output only. See Appendix B and product technical data manuals for more information.
Solid Grounded
(5)
:
-P50 power option NOT
required, quantity of bus
conditioners determined by
the catalog number
High Resistance Grounded
(5)
:
-P50 power option is
required, quantity of bus
conditioners determined by
the catalog number
(5) The appropriate number of bus conditioner units internal to the PowerFlex 755TM non-regenerative supply are factory installed, depending on the frame size and -P50 option selection. For shipboard
ungrounded power sources a marine bus conditioner, option -P51, may be required (contact Rockwell Automation). See Appendix B for more information about DC Bus Conditioner modules.
400/480V AC PowerFlex 750-Series: frames
1321-M180
(4)
400/480V AC PowerFlex 750-Series: frames 7
SK-Y1-CMCORE1
(4)
400/480V AC PowerFlex 755TM Common Bus Inverter: frames 8…15
(6)
(6) See Appendix B for guidance on PowerFlex 755TM control pod selection.
Not Required
(7)
(7) For PowerFlex 755TM common bus inverters, there are no provisions for AC output common mode cores; however, an optional reflective wave (dv/dt) filter is available. See catalog number position 11
- filtering and CM cap configuration, EMI solutions.
Kinetix 5700 single-axis servo drives: (2198-Sxxx-ERSx)
(8)
(8) To connect Kinetix 5700 servo drives to a common DC bus system, a capacitor module and other equipment is required. See Kinetix 5700 Servo Drives on page 102 for more information.
Not Required
Kinetix 5700 dual-axis servo drives: (2198-Dxxx-ERSx)
(8)
Not Required
600/690V AC
1…6
(1)
PowerFlex 755TM
Non-regenerative
Supply
(2)
(20JEH...):
Single Density,
Dual Density
n
(3)
600V AC PowerFlex 750-Series: frames 3…5
(9)
(10)
(9) When 600V AC frame 3...5 inverters are mixed with larger frame inverters on 600V AC common DC bus systems, an external DC bus voltage control method 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.
(10) 600V AC frame 3…5 inverters can’t be used on 690V AC systems. See Appendix D for more information.
Fr.3: 1321-M048
(4)
Fr.4…5: 1321-M180
(4)
600/690V AC PowerFlex 750-Series: frames 6…7
Fr.6: 1321-M180
(4)
Fr.7: SK-Y1-CMCORE1
(4)
600/690V AC PowerFlex 755TM Common Bus Inverter: frames 8…15
(6)
Not Required
(7)
ATTENTION: The PowerFlex 755T non-regenerative supply does not
employ overload protection devices or current limitation controls. Overload
protection devices may be required to protect the non-regenerative
supply and system DC bus bars. You’re responsible for installing
appropriate fuses and/or circuit breakers as recommended in the product
user manual, publication 750-UM100
, and as required by national and local
electrical safety codes and regulations.
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