Drive behavior when STO is activated before rotational speed "0" is reached

NOTICE

Danger due to incorrect parameter setting.
If the parameter Functions > Drive functions > FCB01 Output stage inhibit > Activate DynaStop® for STO = "1", the DynaStop® function can be activated outside the permitted 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 DynaStop® in conjunction with STO with control according to SS1-t.
  • Use the factory setting/recommended setting of the parameter.

If STO is activated before speed "0" is reached, If the DynaStop® function behaves according to the setting of parameter Functions > Drive functions > FCB01 Output stage inhibit > Activate DynaStop® for STO:

Index

Parameter

Setting

Meaning

8501.4

Functions >
Drive functions >
FCB01 Output stage inhibit >
Activate DynaStop® for STO

0 = No

(Factory setting)

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 setting:

  • Functions > Drive functions > FCB01 Output stage inhibit > Activate DynaStop® for STO = 0 (No) factory setting.

[2]

Parameter setting:

  • Functions > Drive functions > FCB01 Output stage inhibit > Activate DynaStop® for STO = 1 (Yes)

t

Time

t1

Point in time at which the deceleration ramp is initiated

t2

Point in time at which STO is activated

Δt

Time span between initiating the deceleration ramp and STO

Range of safe time delay

Range with active, safety-related STO function

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

Reasons for early activation of STO can be:

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