Siemens SINAMICS S120 Function Manual page 199

Inadvertent acceleration of individual drives
If several Motor Modules are supplied from a non-regenerative infeed unit (e.g. a Basic Line
Module), or for power failure or overload (for SLM/ALM), the Vdc_max control may only be
activated for a Motor Module whose drive should have a high moment of inertia.
For the other Motor Modules this function must be disabled or monitoring must be set.
If the Vdc_max control is active for several Motor Modules, then for an unfavorable
parameterization, the controllers can mutually influence one another negatively. The drives
can become unstable, individual drives can unintentionally accelerate.
• Activating the Vdc_max control:
• Inhibiting the Vdc_max control:
• Activating the Vdc_max monitoring function
Drive functions
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
WARNING
– Vector control: p1240 = 1 (factory setting)
– Servo control: p1240 = 1
– U/f control: p1280 = 1 (factory setting)
– Vector control: p1240 = 0
– Servo control: p1240 = 0 (factory setting)
– U/f control: p1280 = 0
– Vector control: p1240 = 4 or 6
– Servo control: p1240 = 4 or 6
– U/f control: p1280 = 4 or 6
Vector control
4.10 Vdc control
197