Rockwell Automation Allen-Bradley PowerFlex 700AFE, User Manual

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Rockwell Automation Publication 20Y-UM001F-EN-P - April 2017 169
Application Notes Appendix C
• The fault relay of both AFEs must be interlocked with each other, such
that both AFEs are disabled (not running) when either AFE is faulted.
• An AFE can be connected while other parallel AFE units are running.
When connecting the AFE to the DC bus, follow these steps in the
order shown.
a. Precharged the isolated AFE.
When completed, the AFE control closes the contactor.
b. To connect the AFE to the DC bus, close the DC disconnect.
When disconnecting the AFE from the DC bus, follow these steps in
the order shown.
a. Stop the inverters and AFEs connected to the same DC bus from
modulating.
The AFE load must be zero before being disconnected to reduce the
load on the contactor.
b. Open the contactor of the AFE.
c. Open the DC disconnect switch.
d. Restart the other AFE units.
• When AFEs are paralleled, the DC bus voltage at regeneration is 5%
higher than with one AFE due to the 5% droop. See Drives in Common
Bus Configurations, publication DRIVES-AT002, for supported drives
that can be used in various AFE configurations.
• Figure 56 on page 170 shows an example of paralleling two AFEs in
their IP20 2500 MCC Style enclosures, where each AFE has its own
precharging circuit, precharging control, and fusing on the DC bus
output and main contactor.
In this case, turn the disconnects (Q0) of all AFEs to ON, and set all
REM-AUTO-MAN selector switches on the door to AUTO to enable
automatic operation.
When turning on the main power, the two AFEs precharge
automatically. After charging, the contactors (K1) are closed and the
AFEs start the modulation. The control signal ‘Inverter Enable’ shown
in Figure 23 on page 45 can be used to interlock the drives connected to
the DC bus.