Siemens SINAMICS G110M - Function Description

Functions
8.10 Safe Torque Off (STO) safety function
SINAMICS G110M Operating Instructions
Operating Instructions, 04/2015, FW V4.7.3, A5E31298649B AD
243
8.10.1
Function description
How does the STO safety function work?
The inverter with active STO prevents machine
components from inadvertently starting.
Table 8- 25 The principle of operation of STO
Safe Torque Off (STO)
Standard inverter functions linked with STO
1. The inverter recognizes the selection of STO
via a safety-relevant input or via the PROFIsafe
safe communication.
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2. The inverter prevents energy from being fed to
the motor. When STO is active, the motor does
not generate any torque.
If you use a motor holding brake, the inverter
closes the brake.
3. The inverter signals that "STO is active" via a
safety-relevant output or via the PROFIsafe
safe communication.
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Figure 8-41 Functionality of STO when motor is rotating and at a standstill
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)."