Siemens SINAMICS S120 Function Manual page 274

U/f control (vector control)
6.4 Vdc control
Vdc_min control
Figure 6-8
In the event of a power failure, V
undershot. This controls the DC-link voltage and maintains it at a constant level. The motor
speed is reduced.
When the line supply returns, the DC-link voltage increases again. 5% above the V
switch-on level, the V
normally.
If the power supply is not re-established, the motor speed continues to drop. When the
threshold in p1297 is reached, this results in a response in accordance with p1296.
Once the time threshold (p1295) has elapsed without the line voltage being re-established, a
fault is triggered (F07406), which can be parameterized as required (factory setting: OFF3).
The V
the DC link, by transferring to them a scaling of their speed setpoint from the controlling drive
via BICO interconnection.
Note
If a voltage recovery is expected, you must make sure that the converter is not disconnected
from the line supply. It could become disconnected, for example, if the line contactor drops
out. The line contactor must be supplied, e.g. from an uninterruptible power supply (UPS).
274
Switching V control on/off (kinetic buffering)
dc_min
control is switched off again. The motor continues operating
dc_min
controller can be activated for a drive. Other drives can participate in supporting
dc_min
is activated when the V
dc_min
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
switch-on level is
dc_min
dc_min
Drive functions