Siemens SINAMICS S120 Function Manual page 525

6-pulse parallel connection of Basic Line Modules
With the 6-pulse parallel connection, up to four Basic Line Modules are supplied by a
common two-winding transformer on the line side and controlled by a common Control Unit.
12-pulse parallel connection of Basic Line Modules
For 12-pulse parallel connections, up to four Basic Line Modules are supplied by a three-
winding transformer on the line side. In this case, an even number of modules, i.e. two or
four, must be divided between the two secondary windings. The Basic Line Modules of both
subsystems are controlled by a common Control Unit - even though the input voltages are
30° out of phase.
There is also the redundant version with which two BLMs in each case are controlled by one
Control Unit.
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), 04/2014, 6SL3097-4AB00-0BP4
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
Function modules
8.10 Parallel connection of power units
525