Safe Torque Off (Sto) Safety Function; Principle Of Operation - Siemens SINAMICS G120D Operating Instructions Manual

Advanced commissioning

8.12 Safe Torque Off (STO) safety function

8.12 Safe Torque Off (STO) safety function
8.12.1

Principle of operation

Overview
An active STO function prevents energy from being fed 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.
Requirement
The machine manufacturer has already performed a risk assessment, e.g. in compliance with
EN ISO 1050, "Safety of machinery - Principles of risk assessment". The risk assessment must
confirm that it is permissible to use the STO safety function.
Function description
Table 8-24
1. The converter recognizes the selection of STO via
2. The converter interrupts the energy supply to the
3. The converter signals that "STO is active" via a
178
Principle of operation of STO
Safe Torque Off (STO)
a safety-relevant input or via the PROFIsafe safe
communication.
motor.
safety-relevant output or via the PROFIsafe safe
communication.
Standard converter functions linked with STO
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If you use a motor holding brake, the converter
closes the brake.
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Converter with the control units CU240D-2
Operating Instructions, 10/2020, FW V4.7 SP13, A5E34262100B AH