Power Loss 73
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
The following terms are used internally by the drive and are defined below for a
complete understanding of power loss functionality.
Table E PF70EC Bus Levels
70EC
700VC
700H
✔✔
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 V
bus
. The filtered value ramps at 2.4V
DC per minute (for a 480VAC drive). An increase in V
mem
is blocked during deceleration
to prevent a false high value due to the bus being pumped up by regeneration. Any
change to V
mem
is blocked during inertia ride through.
Vslew The rate of change of V
mem
in volts per minute.
Vrecover The threshold for recovery from power loss.
Vtrigger The threshold to detect power loss.
PowerFlex 700VC
The level is adjustable. The default is the value in the PF700 Bus Level table. If “Pwr
Loss Lvl” is selected as an input function AND energized, V
trigger
is set to Vmem minus
[Power Loss Level]. Vopen is normally 60V DC below V
trigger
(in a 480VAC drive). Both
V
open
and V
trigger
are limited to a minimum of V
min
. This is only a factor if [Power Loss
Level] is set to a large value.
PowerFlex 70EC
This is a fixed value.
WARNING:
When using a value of Parameter #186 [Power Loss Level] larger than default, the
customer must provide a minimum line impedance 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 5 times the drive’s input VA rating.
Vinertia The software regulation reference for V
bus
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 V
open
.
Voff The bus voltage below which the switching power supply falls out of regulation.
Class 200/240 VAC 400/480 VAC 600/690 VAC
V
slew
1.2V DC 2.4V DC 3.0V DC
V
recover
V
mem
– 30V V
mem
– 60V V
mem
– 75V
V
close
V
mem
– 60V V
mem
– 120V V
mem
– 150V
V
trigger1
V
mem
– 60V V
mem
– 120V V
mem
– 150V
V
trigger2
V
mem
– 90V V
mem
– 180V V
mem
– 225V
V
open Vmem
– 90V V
mem
– 180V V
mem
– 225V
V
min
204V DC 407V DC 509V DC
V
off
? 300V DC ?
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