Passive Loads - Siemens SINAMICS S120 Function Manual

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Vector control

5.2 Vector control without encoder (SLVC)

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.

Make the following settings for this:

1. Set p0500 = 2 (technological application = passive loads for encoderless control to f = 0).

2. Set p0578 = 1 (calculate technology-dependent parameters).

The following parameters are then set automatically:

– p1574 = 2 V for induction motors

– p1574 = 4 V for separately excited synchronous motors

– p1750.2 = 1, closed-loop operation down to 0 Hz for passive loads

– p1802 = 4 SVM/FLB without overcontrol

– p1803 = 106% (factory setting)

As a consequence, the "Passive load" function is automatically activated.

If p0500 is parameterized when commissioning the motor, the calculation is carried out

automatically via p0340 and p3900. p0578is is then set automatically.

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.

Generator operation

Steady-state generator operation at frequencies close to 0 Hz is not permissible in this

operating mode.

Function Manual, 11/2017, 6SL3097-4AB00-0BP5

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