When working with Tolomatic electric actuators, the inertia ratio is referring to the ratio between the actuator’s reflected inertia and the motor’s rotor inertia. The inertia ratio is important for tuning of the motor. If the ratio is too high then overshooting the commanded position could occur. For Tolomatic motors a ratio of 10:1 or less is recommended.
The actuator’s reflected inertia can be calculated using the Tolomatic sizing software and the motor’s rotor inertia is can typically be found as a publish value from the motor manufacturer. The ratio is determined as the actuator reflected inertia divided by the motor rotor inertia.