Allen-Bradley PowerFlex 70 Reference Manual page 134

Power Loss
The drive faults with a F003 – Power Loss fault if the power loss timer exceeds
[Power Loss Time] and the Power Loss bit in [Fault Config 1] is set.
The drive faults with a F004 – UnderVoltage fault if the bus voltage falls below
Vmin and the UnderVoltage bit in [Fault Config 1] is set.
The pre-charge relay opens if the bus voltage drops below Vopen and closes if the
bus voltage rises above Vclose.
If the "pulse" input is re energized and the pre-charge relay is closed, the drive
determines the power loss is over. The power loss alarm is cleared.
If the drive is in a "run permit" state, the reconnect algorithm is run to match the
speed of the motor. The drive then accelerates at the programmed rate to the set
speed.
Decel Input (PF700 only)
This mode can provide additional ride through time by sensing the power loss via
an external device that monitors the power line and provides a hardware power
loss signal. This signal is then connected to the drive through the "pulse" input
(because of its high-speed capability). Normally this hardware power loss input
will provide a power loss signal before the bus drops to less than Vopen.
The drive determine a power loss has occurred if the "pulse" input is de-energized
or the bus voltage drops below Vopen.
If the drive is running, the inertia ride through function is activated. The load is
decelerated at just the correct rate so that the energy absorbed from the
mechanical load balances the losses and bus voltage is regulated to the value
Vmem.
If the output frequency drops to zero or if the bus voltage drops below Vopen or if
any of the "run permit" inputs are de-energized, the inverter output is disabled
and the motor coasts.
The power loss alarm in [Drive Alarm 1] is set and the power loss timer starts.
The Alarm bit in [Drive Status 1] is set if the Power Loss bit in [Alarm Config 1]
is set.
The drive faults with a F003 – Power Loss fault if the power loss timer exceeds
[Power Loss Time] and the Power Loss bit in [E238 Fault Config 1] is set.
The drive faults with a F004 – UnderVoltage fault if the bus voltage falls below
Vmin and the UnderVoltage bit in [Fault Config 1] is set.
The pre-charge relay opens if the bus voltage drops below Vopen and closes if the
bus voltage rises above Vclose.
If power recovers while the drive is still in inertia ride through the power loss
alarm is cleared and it then accelerates at the programmed rate to the set speed.
Otherwise, if power recovers before power supply shutdown, the power loss
alarm is cleared.
If the drive is in a "run permit" state, the reconnect algorithm is run to match the
speed of the motor. The drive then accelerates at the programmed rate to the set
speed.
134 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013