Siemens SINAMICS G150 Operating Instructions Manual page 490

Functions, monitoring, and protective functions
9.2 Drive functions
If a speed threshold set with parameter p1257 (p1297) is undershot when Vdc_min control is
active (see diagram "Switching Vdc_min control on/off" <2>), the drive is shut down with
F7405 (drive: kinetic buffering minimum speed not reached).
If a shutdown with undervoltage in the DC link (F30003) occurs without the drive coming to a
standstill despite the fact that Vdc_min control is active, the controller may have to be
optimized via dynamic factor p1247 (p1287). Increasing the dynamic factor in p1247 (p1287)
causes the controller to intervene more quickly. The default setting for this parameter,
however, should be sufficient for most applications.
Parameter p1256 = 1 (p1296) can be used to activate time monitoring for kinetic buffering.
The monitoring time can be set in parameter p1255 (p1295). If buffering (i.e. the power
failure) lasts longer than the time set here, the drive is switched off with fault F7406 (drive:
kinetic buffering maximum time exceeded). The standard fault reaction for this fault is OFF3,
which means that this function can be used for controlled drive deceleration in the event of a
power failure. In this case, excess regenerative energy can only be dissipated via an
additional braking resistor.
Description of Vdc_max control
Figure 9-5
The switch-on level of the Vdc_max control (r1242 or r1282) is calculated as follows:
● when the automatic switch-on level sensing is disabled (p1254 (p1294) = 0)
– ACAC device: r1242 (r1282) = 1.15 x √2 x p0210 (device supply voltage)
– DCAC device: r1242 (r1282) = 1.15 x p0210 (device supply voltage)
● when the automatic switch-on level sensing is enabled (p1254 (p1294) = 1)
r1242 (r1282) = Vdc_max - 50 V (Vdc_max: overvoltage threshold of the converter)
490
Activating/deactivating the Vdc_max control
Converter cabinet units
Operating Instructions, 07/2016, A5E03347396A