Festo CMMO-­ST DION Série Description Et Mode D'emploi page 30

CMMO­ST-...-DION/DIOP
Caution
When the power output stage is switched off, the actuators can move unpredictably,
causing severe injuries. The STO function is insufficient as the sole safety function for
drives that are subject to permanent torque (e.g. through suspended loads).
• Clamp the powered-down actuators mechanically if required, e.g. via a brake. This
especially applies to vertical axes without automatic locking mechanical arrange­
ment, clamping units or counterweights.
• Prevent movement of the actuators caused by suspended loads or other external
forces, e.g. with a mechanical holding brake.
Note
Controlling motors with an integrated holding brake.
The holding brake is actuated by the non-safety-relevant firmware of the motor control­
ler. When the output stage is switched off there is no deceleration of the drive via a
braking ramp. The holding brake tightens immediately.
• Check whether the integrated holding brake can stop the actuators.
• Note the mechanical inertia of the holding brake.
• Take into consideration the higher wear of the holding brake in comparison to auto­
matic brake control in normal operation.
Note
Failure of the output stage.
If the output stage of the motor controller fails when an STO function is active, it may
result in the drive jerking through a limited detent movement of the rotor. The rotation
angle/travel corresponds to the pole pitch of the motor used.
Example of a failure of the output stage: Simultaneous short-circuiting of 2 power semi­
conductors in different phases.
30 Festo – GDPC-CMMO­ST-EA-S1-Z6 – 2017-05d – English