Allen-Bradley PowerFlex 70 Reference Manual page 130

Power Loss
130
Restart after Power Restoration
If a power loss causes the drive to coast and power recovers the drive will return to
powering the motor if it is in a "run permit" state. The drive is in a "run permit"
state if:
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 Actions
The drive is designed to operate at a nominal bus voltage. When Vbus 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 will have
three methods of dealing with low bus voltages:
• "Coast" – Disable the transistors and allow the motor to coast.
• "Decel" – Decelerate the motor at just the correct rate so that the energy
absorbed from the mechanical load balances the losses.
• "Continue" – Allow the drive to power the motor down to half bus voltage.
184 [Power Loss Mode]
Sets the reaction to a loss of input power. Power loss is
recognized when:
•
DC bus voltage is ≤ 73% of [DC Bus Memory]
and [Power Loss Mode] is set to "Coast".
•
DC bus voltage is ≤ 82% of [DC Bus Memory]
and [Power Loss Mode] is set to "Decel".
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.
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.
The pre-charge relay opens if the bus voltage drops below Vopen and closes if the
bus voltage rises above Vclose
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Default: 0 "Coast"
Options: 0 "Coast"
1 "Decel"
2 "Continue"
3 "Coast Input"
4 "Decel Input"
013
185