The distinction between Emergency Off and Emergency Stop
"Emergency Off" and "Emergency Stop" are commands that minimize different risks in the
machine or plant.
The STO function is suitable for achieving an Emergency Stop but not an Emergency Off.
Risk:
Risk of electric shock:
Risk of unexpected motion:
Measure to minimize
risk:
Safe switch off
Switching off the electric power supply
for the installation, either completely
or partially.
Safely stop and safely prevent restart‐
ing
Stopping or preventing the dangerous
movement
Command:
Emergency Off
Emergency Stop
Classic solution:
Switch off the power supply:
Switch off the drive power supply:
0
Solution with the STO
safety function inte‐
grated in the drive:
STO is not suitable for safely switch‐
ing off an electric voltage.
Select STO:
It is permissible that you switch off the
inverter power supply as well. Howev‐
er, switching off the voltage is not re‐
quired as a risk-reduction measure‐
ment.
Description
3.7 An overview of the principle of operation of the safety functions
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
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Function Manual, 01/2017, FW V4.7 SP6, A5E34261271B AD