Functions, monitoring, and protective functions
9.3 Extended functions
Converter cabinet units
570 Operating Instructions, 07/2016, A5E03347396A
Figure 9-25 Calculating the moment of inertia
The moment of inertia J of the motor and load is then obtained from the accelerating torque
M
B
and the angular acceleration α
J = M
B
/ α
The following conditions must be fulfilled for this calculation:
The rated acceleration torque M
B
must satisfy the following two conditions:
M
B
must be greater than p1560 x r0333 (rated motor torque).
M
B
must be greater than 80% of the friction torque (0.4 x (p1563 - p1564)).
For operation without encoder, the speed must be > p1755 (in closed
-loop controlled
The converter calculates the load torque again after acceleration.
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).
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