Siemens Sinamics S120 Function Manual page 147

Passive loads
In the closed-loop controlled mode, for passive loads, induction motors can be operated
under steady-state conditions down to 0 Hz (standstill) without changing over into the open-
loop controlled mode.
To implement this set
1. p0500 = 2 (technological application = passive loads for encoderless control to f = 0).
2. Then set p0578 = 1 (calculate technology-dependent parameters).
As a consequence, the passive load function is automatically activated.
Note
If p0500 is parameterized when commissioning the motor, the calculation is carried out
automatically via p0340 and p3900. P0578 is then automatically set.
Closed-loop control without changeover between closed-loop and open-loop speed control is
restricted to applications with passive load:
A passive load only has a reactive effect on the drive torque of the driving motor at the
starting point, e.g. high inertia masses, pumps, fans, centrifuges, extruders, travel drives, or
horizontal conveyors.
Standstill without a holding current is possible for as long as required. Then, at standstill,
only the magnetizing current is impressed in the motor.
NOTICE
Generator operation
Steady-state generator operation at frequencies close to 0 Hz is not permissible in this
operating mode.
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
The following parameters are then set automatically:
– p1574 = 2 V, separately-excited synchronous motors = 4 V
– p1750.2 = 1, closed-loop operation down to 0 Hz for passive loads
– p1802 = 4 SVM/FLB without overcontrol)
– p1803 = 106% (factory setting)
4.1 Sensorless vector control (SLVC)
Vector control
145