Safe Torque Off (Sto) - Siemens SINAMICS S120 Function Manual

10.4

Safe Torque Off (STO)

In conjunction with a machine function or in the event of a fault, the "Safe Torque Off" (STO)
function is used to safely disconnect the torque-generating energy supply to the motor.
A restart is prevented by the two-channel pulse suppression. The switching on inhibited
prevents an automatic restart after deselection of STO.
The two-channel pulse suppression function integrated in the Motor Modules / Power
Modules is the basis for this function.
Functional features of "Safe Torque Off"
● The function is completely integrated in the drive. It can be selected via terminals or
● The function is drive-specific, i.e. it is available for each drive and must be individually
● The function must be enabled using parameters.
● When the "Safe Torque Off" function is selected, the following applies:
● The selection/deselection of the STO function also acknowledges the safety faults when
● Extended acknowledgement:
● The status of the "Safe Torque Off" function is displayed using parameters (r9772, r9872,
Unwanted motor motion
Appropriate measures must be taken to ensure that the motor does not undesirably move
once the energy feed has been disconnected, e.g. against coasting down or for a
hanging/suspended axis, the "Safe Brake Control" (SBC) function should be enabled, see
also Section "Safe Brake Control (SBC) (Page 599)".
Drive functions
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
PROFIsafe from an external source.
commissioned.
– The motor cannot be started accidentally.
– The pulse suppression safely disconnects the torque-generating energy supply to the
motor.
– The power unit and motor are not electrically isolated.
the Basic Functions are used. The standard acknowledgement mechanism must also be
performed.
The selection/deselection of STO can also acknowledge the safety messages of the
extended safety functions. This requires that the extended alarm acknowledgement is
configured (p9507.0 = 1).
If in addition to the "Extended Functions", the "Basic Functions via terminals" are also
enabled, in addition to selection/deselection of STO via PROFIsafe or TM54F,
acknowledgement is also possible by selection/deselection of STO via terminals.
r9773 and r9774).
WARNING
Safety Integrated basic functions
10.4 Safe Torque Off (STO)
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