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

Setting functions

8.8 Safe Torque Off (STO) safety function

8.8 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 will find a detailed description of all safety functions and control using PROFIsafe in the
Safety Integrated Function Manual, see Section Manuals for your converter (Page 461).
8.8.1

Function description

Definition according to 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)."
Application examples
Example
When the Emergency Stop button is
pressed, it is not permissible that a
stationary motor undesirably starts.
A central Emergency Stop button ensures
that several drives cannot unintentionally
start.
How does STO function in detail?
The inverter recognizes the
selection ofSTO via a fail-safe
input or via the safe
communicationPROFIsafe.
The inverter then safely switches
off the torque of the connected
motor.
If no motor holding brake is
present, the motor coasts to a
standstill.
If you use a motor holding brake,
the inverter closes the brake
immediately after selecting STO.
302
Possible solution
Wire the Emergency Stop button with a fail-safe
•
input.
Select STO via the fail-safe input.
•
Evaluate the Emergency Stop button in a central
•
control.
Select STO via PROFIsafe.
•
Converter with the CU250S-2 Control Unit (vector)
Operating Instructions, 06/2013, FW V4.6, A5E31759476B AB