Danfoss VLT AutomationDrive FC 302 Programming Manual page 146

Parameter Descriptions
14-10 Mains Failure
Note:
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
144
VLT
Function:
The DC-level during [4] Kinetic back-up is
parameter 14-11 Mains Voltage at Mains Fault *
1.35.
If the mains do not return U is maintained as
DC
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 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 one 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 motoric. The same
mechanism as in point 2, but where the
inertia prevents that the speed goes
above the reference speed. This leads to
the motor running motoric 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 trip, 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.
®
AutomationDrive FC 301/302 Programming Guide
14-10 Mains Failure
Note:
Options [1], [2], [5], [7] are not active when the option [2] Torque
is selected in parameter 1-00 Configuration Mode.
Option:
DC
to [6] Alarm
DC
[7] Kin.
back-up,
trip w
recovery
MG33MI02 - Rev. 2013-11-20
Function:
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 3.54 Kinetic Back-up Trip
Limitation:
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, config-
urable 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.
D
t [S]
t [S]