Siemens SINAMICS S120 Function Manual page 216

Vector control
5.10 Vdc control
Vdc_min control
Figure 5-15
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 power supply is restored, the DC-link voltage increases again and V
deactivated again at 5% above the V
normally.
If the power supply is not re-established, the motor speed continues to drop. When the
threshold in p1257 is reached, this results in a response in accordance with p1256.
Once the time threshold (p1255) 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 drive line-up 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).
216
Switching V control on/off (kinetic buffering)
dc_min
controller can be activated for a drive. Other drives can participate in supporting
dc_min
is activated when the V
dc_min
switch-on level. The motor continues operating
dc_min
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
switch-on level is
dc_min
control is
dc_min
Drive functions