Danfoss VLT AQUA Drive FC 202 Programming Manual page 135

Parameter Description
14-10 Mains Failure
Option: Function:
U [V]
DC
U
DC
14-11*1.35
n [RPM]
Ref
A Normal operation
B Mains failure
C Kinetic back-up
D Mains return
E Normal operation: ramping
Illustration 3.45 Kinetic Back-up
The DC level during [4] Kinetic back-up equals
parameter 14-11 Mains Fault Voltage Level x 1.35.
If the mains does not return, U
long as possible by ramping the speed down
towards 0 RPM. Finally, the frequency converter
coasts.
If the mains return while in kinetic back-up mode,
U increases above parameter 14-11 Mains Fault
DC
Voltage Level x 1.35. This is detected in 1 of the
following ways:
•
If U > parameter 14-11 Mains Fault
DC
Voltage Level x 1.35 x 1.05.
•
If the speed is above the reference. This
is relevant if the mains come back at a
lower level than before, for example
parameter 14-11 Mains Fault Voltage Level
x 1.35 x 1.02. This does not fulfill the
criterion in point 1, and the frequency
converter tries to reduce U
parameter 14-11 Mains Fault Voltage Level
x 1.35 by increasing the speed. This
cannot be done as the mains cannot be
lowered.
•
If running mechanically. The same
mechanism as in point 2 applies, but the
inertia prevents the speed from going
above the reference speed. This leads to
the motor running mechanically until the
speed is above the reference speed and
the situation in point 2 occurs. Instead of
waiting for that criterion, point 3 is
introduced.
[5] Kinetic The difference between kinetic back-up with and
back-up, without trip is that the latter always ramps down
trip to 0 RPM and trips, regardless of whether mains
returns or not.
MG20OB02
Programming Guide
A B C D E A
t [S]
t [S]
is maintained as
DC
to
DC
Danfoss A/S © 05/2018 All rights reserved.
14-10 Mains Failure
Option: Function:
The function does not detect if mains return. This
is the reason for the relatively high level on the
DC link during ramp down.
U [V]
DC
790 V
U DC
14-11*1.35
n [RPM]
Ref
0
A Normal operation
B Mains failure
C Kinetic back-up
D Trip
Illustration 3.46 Kinetic Back-up Trip
[6] Alarm
[7] Kin.
This option is valid in VVC
back-up,
with recovery combines the features of kinetic
trip w
back-up and kinetic back-up with trip. This feature
recovery
makes it possible to select between kinetic back-
up and kinetic back-up with trip, based on a
recovery speed, configurable in
parameter 14-15 Kin. Back-up Trip Recovery Level. If
mains do not return, the frequency converter
ramps down to 0 RPM and trips. If mains return
while in kinetic back-up at a speed above the
value in parameter 14-15 Kin. Back-up Trip Recovery
Level, normal operation is resumed. This is equal
to [4] Kinetic Back-up. The DC level during [7]
Kinetic back-up is parameter 14-11 Mains Fault
Voltage Level x 1.35.
A B C D
t [S]
t [S]
+
only. Kinetic back-up
133
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