Siemens SINAMICS S120 - Page 310

V/f control (vector control)
6.5 Vdc control
Drive functions
310 Function Manual, 11/2017, 6SL3097-4AB00-0BP5
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 V
dc_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 V
dc_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.
Remedial measures:
● activate the V
dc_max
control:
– Vector control: p1240 = 1 (factory setting)
– Servo control: p1240 = 1
– V/f control: p1280 = 1 (factory setting)
● Inhibit V
dc_max
control:
– Vector control: p1240 = 0
– Servo control: p1240 = 0 (factory setting)
– V/f control: p1280 = 0
● Activate the V
dc_max
monitoring
– Vector control: p1240 = 4 or 6
– Servo control: p1240 = 4 or 6
– V/f control: p1280 = 4 or 6
WARNING
Unexpected motion of individual drives
If several Motor Modules are supplied from one infeed unit, then if the V
dc_max
control is
incorrectly parameterized, individual drives can accelerate in an uncontrolled fashion -
which can lead to death or severe injury.
• Only activate the V
dc_max
control for the Motor Module whose drive has the highest
moment of inertia.
• Inhibit this function for all other Motor Modules, or set this function to monitoring only.