Siemens Sinamics S120 Function Manual page 101

To prevent encoder evaluation alarms in encoderless operation, set p1402.1 = 1 to park the
encoder evaluation. Reading in the motor temperature via the encoder evaluation remains
active.
Operation without an encoder is displayed in parameter r1407.1.
Figure 3-20 Area switchover
Note
In closed-loop control operating mode "Speed controller without encoder", a rotor position
encoder is not required. Temperature evaluation remains active, even when the encoder is
parked. This state can be identified at parameter r0458.26 = 1. When parameter r0458.26 =
0, temperature sensing is also deactivated.
Series reactor
When high-speed special motors are used, or other low leakage induction motors, a series
reactor may be required to ensure stable operation of the current controller.
The series reactor can be integrated via p0353.
Commissioning/optimization
1. Estimate the motor current p1612 on the basis of the mechanical conditions (I = M/kt).
2. Set Kn (p1470) and Tn (p1472) above I/f operation (> p1755). The load moment of inertia
3. Determine the load moment of inertia in the speed range above I/f operation (> p1755) by
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
should be set to zero here (p1498 = 0), since this deactivates part of the torque pre-
control.
setting p1498 via a ramp response (e.g. ramp time 100 ms) and assessing the current
(r0077) and model speed (r0063).
3.11 Sensorless operation (without an encoder)
Servo control
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