4.2 Specifications and Ratings
4.2.6 Load Moment of Inertia
4
Specifications, Ratings, and Exter
nal Dimensions of SGM7J Servomotors
4-9
4.2.6
Load Moment of Inertia
The load moment of inertia indicates the inertia of the load. The larger the load moment of iner-
tia, the worse the response. If the moment of inertia is too large, operation will become unsta-
ble.
The allowable size of the load moment of inertia (
J
L
) for the Servomotor is restricted. Refer to
on page 4-4. This value is provided strictly as a
guideline and results depend on Servomotor driving conditions.
An Overvoltage Alarm (A.400) is likely to occur during deceleration if the load moment of inertia
exceeds the allowable load moment of inertia. SERVOPACKs with a built-in regenerative resis-
tor may generate a Regenerative Overload Alarm (A.320). Perform one of the following steps if
this occurs.
•
Reduce the torque limit.
•
Reduce the deceleration rate.
•
Reduce the maximum motor speed.
•
Install an External Regenerative Resistor if the alarm cannot be cleared using the above
steps.
Regenerative resistors are not built into SERVOPACKs for 400-W Servomotors or smaller Ser-
vomotors.
Even for SERVOPACKs with built-in regenerative resistors, an External Regenerative Resistor is
required if the energy that results from the regenerative driving conditions exceeds the allow-
able loss capacity (W) of the built-in regenerative resistor.
