28 Rockwell Automation Publication DRIVES-AT005D-EN-P - May 2022
Chapter 2 Regenerative Bus Supply Configuration
9. Verify that the PowerFlex 755TM regenerative bus supply is capable of precharging the external DC bus capacitance.
• The PowerFlex 750-Series internal DC bus capacitance data is taken from Table 14 on page 73
.
• The PowerFlex 755TM common bus inverter internal DC bus capacitance data is taken from Table 15 on page 75
.
• The PowerFlex 755TM regenerative bus supply internal and maximum external capacitance data is taken from Table 16 on page 76
.
The total external capacitance (19900 µF) is less the PowerFlex 755TM regenerative bus supply maximum external capacitance (31033 µF).
The chosen PowerFlex 755TM regenerative bus supply is capable of precharging the connected DC bus capacitance.
10. Verify that the DC bus cable/bus bars are adequately sized for the total rated DC bus current.
The approximate total rated DC bus current is calculated by dividing the total AC output current from step 8 (629 A RMS) by 0.9. Minimum DC
bus bar rating = 629 A RMS / 0.9 = 699 A DC
The standard PowerFlex 755TM DC bus bar is capable of 3000 A DC. All DC bus bars in the common DC bus lineup must have the same amp
rating. See PowerFlex 755TM System DC Bus Ratings on page 99
for more information about the DC bus bar ratings and options.
The chosen PowerFlex 755TM regenerative bus supply is an acceptable solution for this common DC bus application example. Verify that the system
AC and DC bus bars and cables are sized to support the expected current.
Section Name Drive Product Cat No.
DC Bus Capacitance
(µF)
(1)
(1) See Appendix A for rated output amps, internal and maximum capacitance values.
Rated Output
Amps Notes
Drive 1 Powerflex 755TM 20G...E242 4650 192 frame 8, HD
Drive 2 Powerflex 755 20G…E144 5200 125 frame 6, HD
Drive 3 Powerflex 755TM 20G…E295 4650 242 frame 8, HD
Drive 4 Powerflex 755 20G…E052 3600 42 frame 5, HD
Drive 5 Powerflex755 20G…E032 1800 28 frame 4, HD
Bus Supply
Powerflex 755TM Regen 20JxF…E395 4650
365 frame 8, HD
Max External Capacitance 31033
Additional Capacitance 0 µF
Total External Capacitance
(2)
(2) The calculated total external DC bus capacitance excludes the PowerFlex 755TM bus supply internal bus capacitance.
19900 µF
Total DC Bus Capacitance 24550 µF
Total Rated AC Output Amps
(3)
(3) The Total Rated AC Output Amps is the sum of the inverter/drive rated AC output current and excludes the DC output current of the bus supply.
629.0 A RMS
This System target µF/A Ratio 28 µF/A
This system calculated µF/A Ratio 39.0 µF/A
µF/A ratio OK 0 µF additional required
Section Name Drive Product Cat No.
DC Bus
Capacitance
(µF)
(1)
(1) See Appendix A for rated output amps, internal and maximum capacitance values.
Notes
Drive 1 Powerflex 755TM 20G...E242 4650 frame 8, HD
Drive 2 Powerflex 755 20G…E144 5200 frame 6, HD
Drive 3 Powerflex 755TM 20G…E295 4650 frame 8, HD
Drive 4 Powerflex 755 20G…E052 3600 frame 5, HD
Drive 5 Powerflex 755 20G…E032 1800 frame 4, HD
Bus Supply
Powerflex 755TM non-regen 20JxF…E395 4650
frame 8, HD
Max External Capacitance 31033
Additional Capacitance 0
Total External Capacitance
(2)
(2) The calculated total external DC bus capacitance does not include the PowerFlex 755TM bus supply internal bus
capacitance.
19900
Precharge OK
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