Siemens Sinamics S110 Function Manual page 170

Drive functions
7.1 Servo control
Description of Vdc_max control (p1240 = 1, 3)
Figure 7-23
In the event of a power failure, the voltage can increase until it reaches the shutdown
threshold when the drive is decelerated. The Vdc_max controller can be activated to prevent
the system from shutting down due to overvoltage. The Vdc_max controller is normally
activated for drives that have to decelerate/accelerate high levels of kinetic energy
themselves. When the overvoltage threshold in p1244 is reached (recommended setting: 50
V higher than the supply voltage), the braking torque of the drive with an active Vdc_max
controller is reduced by shifting the torque limit. In this way, the drive feeds back the same
amount of energy that is assimilated as a result of losses or consumers, thereby minimizing
the braking time.
Description of Vdc_max control without acceleration (p1240 = 7, 9)
As with p1240 = 1, 3, if the drive must not be accelerated by means of an increase in the
supply voltage, acceleration can be prevented by setting p1240 = 7, 9. The effective lower
torque limit must not be greater than the torque limit offset (p1532).
Description of Vdc controller monitoring functions (p1240 = 4, 5, 6)
In the event of a power failure, the supply voltage can increase until it reaches the shutdown
threshold when the drive is decelerated. To ensure that uncritical drives do not attempt to
draw power from the supply voltage in the event of a power failure, such drives can be
switched off by a fault (F07404) with a parameterizable voltage threshold (p1244). This is
carried out by activating the Vdc_max monitoring function (p1240 = 4, 6).
Function diagrams (see SINAMICS S110 List Manual)
● 5650 Vdc_max controller and Vdc_min controller
● 5300 V/f control
168
Switching-in/switching-out the Vdc_max control
Function Manual, 01/2011, 6SL3097-4AB10-0BP3
Function Manual