KEB COMBIVERT F5-H - Determination of the Mass Moment of Inertia

Page 7.7 - 8 COMBIVERT F5-A, -E, -H © KEB, 2012-10
Speed control
7.7.2 Determination of the mass moment of inertia
Process to determination of the mass moment of inertia
time
Torque Speed
acceleration torque
Delta M = 662 Nm
Delta t = 0.26s
Delta n = 402 rpm
Set speed
calculated actual speed
The knowledge of the mass moment of inertia of the system (= motor + rigidly coupled load) is required for
the automatic calculation of the speed controller parameters as well as for the pre-control of the acceleration
torque.
If this mass moment of inertia is unknown, it can be determined by an acceleration test.
For this the system must be accelerated with dened, constant torque. It must be guaranteed that no signicant
and acceleration-independent load torque occurs by the application.
The following formula is valid:
∆t
———
∆n
J = 95493 x ∆M x
Example: Ramp-up was recorded with COMBIVIS:
0.26 s
——————
402 rpm
J = 95493 x 662 Nm = 40886 kgcm
2
In order to eliminate the effect of friction from the calculation, you can determine the mass moment of inertia a
second time in similar manner, however by deceleration test. The average value of both inertia, which is deter-
mined at ramp-up or deceleration must be entered in parameter cS.25 „inertia (kg cm^2)“.