Siemens SINAMICS G130 Operating Instructions Manual page 472

Functions, monitoring, and protective functions
9.3 Extended functions
Figure 9-25
The moment of inertia J of the motor and load is then obtained from the accelerating torque
M and the angular acceleration α
B
J = M
The following conditions must be fulfilled for this calculation:
①
②
③
If the load estimation has taken place and the moment of inertia does not settle (stabilize)
(r1407.24/26 = 0), then increasing the acceleration (p2572/p2573) is recommended.
If the load moment of inertia is significantly greater than the motor moment of inertia, then
the transient event can also be improved via parameterization of the load moment of inertia
(p1498).
Moment of inertia precontrol
In applications where the motor predominantly operates with a constant speed, the inverter
can only infrequently calculate the moment of inertia using the function described above.
Moment of inertia precontrol is available for situations such as these. The moment of inertia
precontrol assumes that there is an approximately linear relationship between the moment of
inertia and the load torque.
472
Calculating the moment of inertia
/ α
B
The rated acceleration torque M
• M must be greater than p1560 x r0333 (rated motor torque).
B
• M must be greater than 80% of the friction torque (0.4 x (p1563 - p1564)).
B
For operation without encoder, the speed must be > p1755 (in closed-loop controlled
operation).
The converter calculates the load torque again after acceleration.
must satisfy the following two conditions:
B
Operating Instructions, 07/2016, A5E00331449A
Inverter chassis units