Allen-Bradley PowerFlex 70 Reference Manual page 132

Power Loss
132
The inverter output is disabled and the motor coasts 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 pre-charge relay opens if the bus voltage drops below Vopen.
The pre-charge relay closes if the bus voltage rises above Vclose
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 still in inertia ride through operation, the drive immediately
accelerates at the programmed rate to the set speed. If the drive is coasting and 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
Half Voltage
This mode provides the maximum power ride through. In a typical application
230VAC motors are used with a 480VAC drive, the input voltage can then drop
to half and the drive is still able to supply full power to the motor.
ATTENTION: To guard against drive damage, a minimum line
!
impedance must be provided to limit inrush current when the power
line recovers. The input impedance should be equal or greater than
the equivalent of a 5% transformer with a VA rating 6 times the drive's
input VA rating.
The drive determines a power loss has occurred if the bus voltage drops below
Vtrigger.
If the drive is running the inverter output is disabled and the motor coasts.
If the bus voltage drops below Vopen/Vmin (In this mode of operation Vopen
and Vmin are the same value) or if the Enable input is de-energized, the inverter
output is disabled and the motor coasts. If the Not Stop or Run inputs are
de-energized, the drive stops in the programmed manner.
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Table 15 for further information.
680V
620V
560V
500V
407V
305V