Drive-Independent Reactions - Siemens SINUMERIK 840D sl Function Manual

In order to perform retraction outside the AUTOMATIC mode as well, triggering of this
function is linked to the system variable $AC_ESR_TRIGGER. Retraction initiated via
$AC_ESR_TRIGGER is locked, in order to prevent multiple retractions.
6.2.2

Drive-independent reactions

Generator operation
Generator operation is a drive function. Using the "Vdc control" function, the SINAMICS S120
drive unit can monitor the DC link group for undervoltage. When an adjustable voltage value
is fallen below, then the drive intended for the purpose is switched into generator operation.
The kinetic energy of the drive is used to buffer the DC link voltage. This allows the axes that
are still moving to be stopped and retracted in an ordering fashion on the NC side.
Note
At the instant that it is switched into generator operation, if an axis is in closed-loop position
control, then additional alarms can occur.
References
For detailed information on the SINAMICS S120 drive function "Vdc control", see:
• Function Manual SINAMICS S120 Drive Functions
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
R3: Extended stop and retract
6.2 Control-managed ESR
365