Safe Torque Off (Sto) Safety Function; Function Description - Siemens SINAMICS G120 Operating Instructions Manual

6.8

Safe Torque Off (STO) safety function

These operating instructions describe the commissioning of the STO safety function when it
is controlled via a fail-safe digital input.
You can find a detailed description of all safety functions and their control using PROFIsafe
in the "Safety Integrated" function manual.
6.8.1

Function description

What is the effect of the STO safety function?
The inverter with active STO function prevents energy supply to the motor. The motor can no
longer generate torque on the motor shaft.
Consequently, the STO function prevents the starting of an electrically-driven machine
component.
Table 6- 47
1. The inverter recognizes the selection of STO
2. The inverter prevents the energy supply to the
3. The inverter signals that "STO is active" via a
Image 6-61
If the motor is still rotating (B) when STO is selected, it coasts down to standstill.
Converter with the CU240B-2 and CU240E-2 Control Units
Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
Overview of the manuals (Page 507)
The STO principle of operation as overview
Safe Torque Off (STO)
via a safety-relevant input or via the PROFIsafe
safe communication.
motor.
safety-relevant output or via the PROFIsafe
safe communication.
Functionality of STO when the motor is at standstill (A) and rotating (B)
Advanced commissioning
6.8 Safe Torque Off (STO) safety function
Standard inverter functions linked with STO
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If you use a motor holding brake, the inverter
closes the motor holding brake.
If you use a line contactor, the inverter opens
the line contactor.
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