Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 74)

74 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
The drive faults with a F4 “UnderVoltage” fault if the bus voltage falls below
Vmin and the P460 [UnderVltg Action] is set to 3 “FltCoastStop.”
The pre-charge relay opens if the bus voltage drops below Vopen and closes if the
bus voltage rises above Vclose.
If the bus voltage rises above Vrecover for 20 ms, 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.
Coast
This is the default mode of operation. 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.
Decel
This mode of operation is useful if the mechanical load is high inertia and low
friction. By recapturing the mechanical energy, converting it to electrical energy
and returning it to the drive, the bus voltage is maintained. As long as there is
mechanical energy, the ride through time is extended and the motor remains fully
fluxed.
If AC input power is restored, the drive can ramp the motor to the correct speed
without the need for reconnecting. The drive determines a power loss has
occurred if the bus voltage drops below Vtrigger.
If the drive is running, the inertia ride through function is activated.
The load is decelerated at the correct rate so that the energy absorbed from the
mechanical load regulates the DC bus to the value Vinertia.
Bus Voltage
Motor Speed
Power Loss
Output Enable
Pre-Charge
Drive Fault
680V
620V
560V
500V
407V
305V