Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 72)

72 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
Power Loss The drive contains a sophisticated algorithm to manage initial application of
power as well as recovery from a partial power loss event. The drive also has
programmable features that can minimize the problems associated with a loss of
power in certain applications.
Terms and Definitions
Table 8 - PowerFlex 750-Series Bus Levels
Term Definition
Vbus The instantaneous DC bus voltage.
Vmem The average DC bus voltage. A measure of the average bus voltage determined by heavily filtering bus
voltage. Just after the pre-charge relay is closed during the initial power-up bus pre-charge, bus memory
is set equal to bus voltage. Thereafter it is updated by ramping at a very slow rate toward Vbus. The filtered
value ramps at 2.4V DC per minute (for a 480VAC drive). An increase in Vmem is blocked during
deceleration to prevent a false high value due to the bus being pumped up by regeneration. Any change to
Vmem is blocked during inertia ride through.
Vslew The rate of change of Vmem in volts per minute.
Vrecover The threshold for recovery from power loss.
Vtrigger The threshold to detect power loss.
The level is adjustable. The default is the value in the PowerFlex 750-Series Bus Level table. If “Pwr Loss
Lvl” is selected as an input function AND energized, Vtrigger is set to Vmem minus [Pwr Loss Level]. Vopen
is normally 60V DC below Vtrigger (in a 480VAC drive). Both Vopen and Vtrigger are limited to a minimum
of Vmin. This is a factor only if [Pwr Loss Level] is set to a large value.
Important: When using a value of P451/P454 [Pwr Loss A/B Level] that is larger than default, you must
provide a minimum line impedance to limit inrush current when the power line recovers. Provide an input
impedance that is equal to or greater than the equivalent of a 5% transformer with a VA rating 5 times the
drive’s input VA rating.
Vinertia The software regulation reference for Vbus during inertia ride through.
Vclose The threshold to close the pre-charge contactor.
Vopen The threshold to open the pre-charge contactor.
Vmin The minimum value of Vopen.
Voff The bus voltage below which the switching power supply falls out of regulation.
Class 200/240V AC 400/480V AC 600/690V AC
Vslew 1.2V DC 2.4V DC 3.0V DC
Vrecover Vmem – 30V Vmem – 60V Vmem – 75V
Vclose Vmem – 60V Vmem – 120V Vmem – 150V
Vtrigger1,2 Vmem – 60V Vmem – 120V Vmem – 150V
Vtrigger1,3 Vmem – P451/P454 [Power
Loss A/B Level] Vmem – P451/P454 [Power
Loss A/B Level] Vmem – P451/P454 [Power
Loss A/B Level]
Vopen Vmem – P451/P454 [Power
Loss A/B Level] Vmem – P451/P454 [Power
Loss A/B Level] Vmem – P451/P454 [Power
Loss A/B Level]
Vopen4 153V DC 305V DC 382V DC
Vmin 153V DC 305V DC 382V DC
Voff – 200V DC –