Fig 1. Safe torque Off
Caution
The STO
Function by itself
is not an Emergency Stop and may be used as part of an
Emergency Stop control system but all relevant standards must be consulted.
Decision to use STO in a control system must be based on risk assessment, refer to the
relevant standards EN/IEC 62061or EN/ISO 13849-1.
In application of STO due to the coast to stop function take into consideration the
stopping timeof the driven load.
For further information on STO refer to EN61800-5-2 and For stop categories Refer to
EN60204-1
5.
Electromechanical and Safety integrated interface Comparison
Diagrams below show simple Inverter drive configurations for comparison between safe stop
interfaces using electromechanical and Safety integrated type solutions.
STO Activated
IGBT outputs are shut down
Motor Speed Coasts to zero
Stop Category 0 to EN60204-1
v
t
STO
Electromechanical. Without STO function
No SIL. Stop Category 0
Emergencystop
SafetyInterlocks
Electromechanical. Without STO function
No SIL. Stop Category 0
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