Allen-Bradley PowerFlex 70 Reference Manual page 133

The pre-charge relay opens if the bus voltage drops below Vopen/Vmin and closes
if the bus voltage rises above Vclose.
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 [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.
If the bus voltage rises above Vrecover for 20mS, the drive determines the power
loss is over. The power loss alarm is cleared.
If the drive is coasting and if it 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.
Bus Voltage
Motor Speed
Power Loss
Output Enable
Pre-Charge
Drive Fault
480V example shown, see
Coast Input (PowerFlex700 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 determines 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
inverter output is disabled.
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.
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Table 15 for further information.
Power Loss
680V
620V
560V
365V
305V
133