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

Basic Functions

Note
The Basic Functions are also described in the following manual:
Reference: /FH1/SINAMICS S120 Function Manual Drive Functions
3.1

Safe Torque Off (STO)

General description
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 motor power supply.
When the function is selected, the drive unit is in a "safe status". The power-on disable
function prevents the drive unit from being restarted.
The two-channel pulse inhibit integrated in the Motor Modules / Power Modules is a basis for
this function.
Functional features of "Safe Torque Off"
● This function is integrated in the drive; this means that a higher-level controller is not
● The function is drive specific, that is, it must be commissioned individually on a drive-by-
● Enable of the function using parameters required
● When the "Safe Torque Off" function is selected:
Safety Integrated
Function Manual, (FHS) , 07/2007 Edition, 6SL3097-2AR00-0BP0
required.
drive basis.
– The motor cannot be started accidentally.
– The pulse disable safely disconnects the torque-generating motor power supply.
– The power unit and motor are not electrically isolated.
WARNING
Appropriate measures must be taken to ensure that the motor does not move once
the motor power supply has been disconnected ("coast down") (e.g. enable the "Safe
Brake Control" function with a vertical axis).
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