Danfoss VLT AutomationDrive FC 302 Programming Manual page 148

Parameter Descriptions
14-10 Mains Failure
Options [1], [2], [5], [7] are not active when the option [2] Torque
is selected in parameter 1-00 Configuration Mode.
Option:
3 3
[5] Kinetic
back-up,
trip
146
VLT
Function:
If the mains return while in kinetic back-up, U
increases above parameter 14-11 Mains Voltage at
Mains Fault*1.35. This is detected in one of the
following ways.
1. If U > parameter 14-11 Mains Voltage
DC
at Mains Fault*1.35*1.05.
2. If the speed is above the reference. This
is relevant if the mains come back at a
lower level than before, e.g.
parameter 14-11 Mains Voltage at Mains
Fault*1.35*1.02. This does not fulfil the
criterion in point 1, and the frequency
converter tries to reduce U
parameter 14-11 Mains Voltage at Mains
Fault*1.35 by increasing the speed. This
will not succeed as the mains cannot be
lowered.
3. 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 mechan-
ically until the speed is above the
reference speed and the situation in
point 2 occurs. Instead of waiting for
that criterion, 3 is introduced.
The difference between kinetic back-up with and
without trip is that the latter always ramps down
to 0 RPM and trips, regardless of whether mains
return or not.
The function does not detect if mains return. This
is the reason for the relatively high level on the
DC link during ramp down.
A B C
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 3.55 Kinetic Back-up Trip
Limitation:
Danfoss A/S © Rev. 10/2014 All rights reserved.
®
AutomationDrive FC 301/302
14-10 Mains Failure
Options [1], [2], [5], [7] are not active when the option [2] Torque
is selected in parameter 1-00 Configuration Mode.
Option:
DC
[6] Alarm
[7] Kin.
back-up,
trip w
recovery
to
DC
D
t [S]
t [S]
Function:
See the introduction text in
parameter 14-10 Mains Failure.
Kinetic back-up with recovery combines the
features of kinetic back-up and kinetic back-up
with trip. This feature 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. Backup Trip Recovery Level to
enable detection of mains returning. 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. Backup 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 Voltage at Mains
Fault* 1.35.
A B C D A
U [V]
DC
U
DC
14-11*1.35
n [RPM]
Ref
14-15
A Normal operation
B Mains failure
C Kinetic back-up
D Mains return
E Normal operation: ramping
Illustration 3.56 [7] Kinetic Back-Up, Trip with
Recovery where mains return above
parameter 14-15 Kin. Backup Trip Recovery
Level
If mains return while in kinetic back-up at a
speed below parameter 14-15 Kin. Backup Trip
Recovery Level, the frequency converter ramps
down to 0 RPM using the ramp and then trips. If
the ramp is slower than the system ramping
down on its own, the ramping is done mechan-
ically and U is at the normal level (U
DC
A B C D E
U [V]
DC
U
DC
14-11*1.35
n [RPM]
Ref
0
E
t [S]
t [S]
*1.35).
DC, m
F
t [S]
t [S]
MG33MJ02