Safe Torque Off (Sto) - Siemens SINAMICS G120 Function Manual

3.7

Safe Torque Off (STO)

How does the STO safety function work?
Table 3- 2
1. The inverter recognizes the selection of STO
2. The inverter prevents energy from being fed to
3. The inverter signals that "STO is active" via a
Figure 3-1
If the motor is still rotating when STO is selected, then it coasts down to standstill.
The STO safety function is standardized
The STO function is defined in IEC/EN 61800-5-2:
"[...] [The inverter] does not supply any energy to the motor which can generate a torque (or
for a linear motor, a force)."
The STO inverter function complies with what is defined in the standard.
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA
The principle of operation of STO
Safe Torque Off (STO)
via a safety-relevant input or via the PROFIsafe
safe communication.
the motor. When STO is active, the motor does
not generate any torque.
safety-relevant output or via the PROFIsafe
safe communication.
Functionality of STO when motor is rotating and at a standstill
The inverter with active STO function prevents machine
components from inadvertently starting.
Standard inverter functions linked with STO
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If you use a motor holding brake, the inverter
closes the brake.
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Description
3.7 Safe Torque Off (STO)
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