Drive behavior when STO is activated before standstill (rotational speed = "0")

NOTICE

Danger due to incorrect parameter settings
If the parameter With STO brake apply/Activate DynaStop® = "1", (path: Functions > Drive functions > FCB01 output stage inhibit > Brake/DynaStop®), the DynaStop® function can be activated outside the permissible operating range. This can cause high torque loads / high motor currents, which may damage the drive unit and the application.
Possible damage to property.
  • Use the factory settings or recommended settings.

If STO is activated before the speed "0" is reached, the DynaStop® function will behave in accordance with the setting of parameter Apply brake/DynaStop® in STO state (Path: Functions > Drive functions > FCB 01 Output stage inhibit > Brake/DynaStop®):

Index

Parameter

Setting

Meaning

8501.3

Apply brake/activate DynaStop® in STO state

(Path: Functions > Drive functions > FCB01 Output stage inhibit > Brake/DynaStop®)

0 (no)

The DynaStop® status remains unchanged when STO is activated.

  • Depending on the application, the motor will coast to a stop or even accelerate.
  • The stopping distance is undefined.

1 (yes)

DynaStop® is activated (not safety-related) when STO is activated.

  • If DynaStop® is activated before speed "0" is reached, high torques/motor currents can occur that may damage the drive and the application.
  • Evaluate the possible consequences.
  • The stopping distance is undefined.

Recommended setting/factory setting

The following figure shows the behavior when STO is activated before rotational speed "0" is reached:

[1]

 

Parameter:

Apply brake/activate DynaStop® in STO state = "0" (no) factory setting

[2]

 

Parameter:

Apply brake/activate DynaStop® in STO state = "1" (yes)

(Path: Functions > Drive functions > FCB01 Output stage inhibit > Brake/DynaStop®)

t

Time

t1

Point of time when deceleration ramp is initiated

t2

Point of time when STO is triggered

Δt

Time span between initiating the deceleration ramp and STO

Safe time delay range

Range with active, safety-related STO function

Activating the STO function during the deceleration ramp aborts controlled deceleration:

Possible reasons for premature activation of STO:

  • Deceleration time Δt too short
  • Extension of the deceleration ramp when the current limit is reached, e.g. due to too high load