Motor Inertia

Information courtesy of

Motor Data

Power = .................. kW
Speed = .................. Rpm * 0.105 w_m = ............ sec^-1
Moment of inertia J_m = ................. kgm²

If the moment of inertia is not known, the electric motor power can help. The moment of inertia can he found from catalogues of manufacturers of corresponding motors. Moment of inertia is different for AC and DC with the same power. It is also a function of motor speed.
The motor speed must be converted into sec^-1 to fit into the calculation.
Motor speed in Rpm times 0.105 gives w_m = sec^-1

 

Jm moment of inertia AC-motor
Power	Moment of inertia kgm2 for different RPM
kW	3000	1500	1000	750
11	0.055	0.065	0.1	0.25
22	0.13	0.24	0.33	0.73
30	0.19	0.35	0.73	0.9
45	0.31	0.43	1.2	1.7
55	0.6	0.7	1.5	2.4
75	1.2	1.2	2.4	3.2
90	1.4	1.4	2.9	4.0
110	2.2	2.0	3.5	6.0
250	3.7	5.6	9.1	13.0