Siemens SINAMICS G120 Operating Instructions Manual page 313

Preconditions
● You have selected encoderless vector control.
● The load torque must be constant whilst the motor accelerates or brakes.
Typical of a constant load torque are conveyor applications and centrifuges, for example.
Fan applications, for example, are not permitted.
● The speed setpoint is free from superimposed unwanted signals.
● The motor and load are connected to each other with an interference fit.
Drives with slip between the motor shaft and load are not permitted, e.g. as a result of loose
or worn belts.
If the conditions are not met, you must not activate the moment of inertia estimator.
Procedure
1. Set p1400.18 = 1
2. Check: p1496 ≠ 0
3. Activate the acceleration model of the speed controller pre-control: p1400.20 = 1.
You have activated the moment of inertia estimator.
❒
The most important settings
Parameter
r0333
p0341
p0342
p1400
Converter with the CU250S-2 Control Units
Operating Instructions, 04/2018, FW V4.7 SP10, A5E31759476B AG
Explanation
Rated motor torque [Nm]
Motor moment of inertia (factory setting: 0 kgm
The inverter sets the parameter when selecting a listed motor. The parameter is then
write-protected.
Moment of inertia ratio, total to motor (factory setting: 1)
Ratio of moment of inertia load + motor to moment of inertia of motor without load
Speed control configuration
.18 1 signal: Moment of inertia estimator active
.20 1 signal: Acceleration model on
.22 1 signal Moment of inertia estimator retain value when motor switched off
0 signal Moment of inertia estimator reset value to initial value J
switched off:
J = p0341 × p0342 + p1498
0
If the load torque can change when the motor is switched off, set
p1400.22 = 0.
.24 1 signal Shortened moment of inertia estimation is active.
p1400.24 = 1 reduces the duration of the moment of inertia estimation.
Disadvantage: If the accelerating torque is not constant while calculating
the moment of inertia, the calculation of the moment of inertia using
p1400.24 = 1 is less precise.
Advanced commissioning
6.21 Motor control
)
2
0
when motor
311