Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 73)

Rockwell Automation Publication 750-RM002B-EN-P - September 2013 73
Drive Configuration Chapter 1
In the following diagram, the x-axis across the bottom indicates what the input
voltage is into the drive and the y-axis indicates the corresponding DC Bus
Voltage. Then the levels of each event are indicated in the graph. For example if I
measure at the input of my drive, 450 volts - phase to phase, I find that voltage
across the bottom. Now the various voltage levels can be derived according to that
voltage level.
Restart after Power Recovery
If a power loss causes the drive to coast, and power recovers, the drive returns to
powering the motor if it is in a Run Permit state. The drive is in a Run Permit
state if the following is true:
• 3 Wire mode - it is not faulted and if all Enable and Not Stop inputs are
energized.
• 2 Wire mode - it is not faulted and if all Enable, Not Stop, and Run inputs
are energized.
Power Loss Modes
The drive is designed to operate at a nominal input voltage. When voltage falls
below this nominal value by a significant amount, action can be taken to preserve
the bus energy and keep the drive logic alive as long as possible. The drive has
three methods of dealing with low bus voltages.
• “Coast” - Disable the drive and allow the motor to coast. (default)
• “Decel” - Decelerate the motor at a rate that regulates the DC bus until the
load’s kinetic energy can no longer power the drive.
• “Continue” - Allow the drive to power the motor down to 50% of the
nominal DC bus voltage. When power loss occurs, P959 [Alarm Status A]
Bit 0 turns on if the P449 [Power Loss Actn] is set to 1 “Alarm.”
If the P449 [Power Loss Actn] is set to 3 “FltCoastStop,” an F3 “Power Loss” fault
occurs when the power loss event exceeds P452/455 [Pwr Loss A/B Time].
Recover
Closer
Trigger
Open Recover
Closer
Trigger
Open Recover
Closer
Trigger
Open
AC Input Volts AC Input Volts AC Input Volts
Line Loss Mode = Coast Line Loss Mode = Decel Line Loss Mode = Continue
DC Bus
Vo
lts
DC Bu
s V
olts
DC Bu
s V
olts